08 dynasty thermostat issue

[vipeboy2000]

Hey guys.  It's me again . I may have inadvertently fried either my control board in the front ac or the thermostat . 

I had turned off all the 120v breakers to the ac units and hit the battery disconnect in the coach ... but forgot to do the main disconnect at the battery. 

Front ac capacitor failed so was replacing it. Did not notice how tight the phone cable control wire was when re inserting the new capacitor and bent the ports and may have broken a pin.  So I disconnected everything to re solder the connector.  I saw a spark where the 3amp fuse is when it brushed up against a wire and the 3 amp fuse burned.  I re soldered and put a new 3 amp fuse in and re connected everything. I now have no power at all to the inside thermostat . 

 

Thoughts? Thanks everyone.  Of course I decide to do this 5 days before myrtle beach... if we can't get ac we probably will need to cancel as we need to be able to work from the rv and it will he too hot.  

Edited May 3 by vipeboy2000

[Ivan K]

You should have an other 12v fuse in an interior fuse box. Mine is 2A in a bedroom cabinet fuse box. Good luck, hopefully that easy.

[Tom Cherry]

EDIT. 

ADDED THE HVAC PRINT TO POST

END OF EDIT

There is ONE FUSE, Somewhere on the main fuse panel.  It feeds ALL the control modules…zone 1, 2 & 3.  You  have a hidden “controller” for the middle section heat. Zone 4, i think.

There is a clear drawing for this in your prints.  It shows all the zone units and 120 VAC and such.  If you down load the file…open it.  There is a PDF index. 

I can’t really tell how much damage….you may have done….minor or major from your post.

Here is what you need to understand,  There is a 2 Pair or 4 wire “data communications” cable that runs from the thermostat to the front unit….then all the way through the MH. My memory is slack as to whether you have 2 or 1 thermostats.  One pair is 12 VDC.  It powers the thermostat.  The other pair is a Multiplexed pair.

If you broke or destroyed a phone connector wire….UGLY.  The way this works.  Any time you mess with or disconnect or tinker with the HVAC system, you “disconnect” a circuit that is always HOT or live.  SO…after you finish, you have to RESET or REBOOT then entire system,  Turn OFF the bottom switch.  Hold ON MODE and ZONE.  Then power it ON.  FF in the display.  That means the Thermostat has communicated with and done a digital handshake with every controller.  Sort of like holding hands at a prayer session,  BREAK the circuit….it ain't gonna work.  Reset.  WORD OF CAUTION.  Never use the bottom switch for anything except resetting.  Use the Zone snd then toggle the MODE to OFF.  The thermostat is not in production.  Used.  The mechanical swrich is the first to fail.  You DO NOT want to abuse it.

If you blew a House fuse….look on the print or read the owners manual and find out which.  Replace or test it.  NO FF during reset…there is a Communication open circuit. You can remove the front controller and the the rear controller (top side) and swap.  This is the quickest troubleshooting technique.  You MUST set the DIP switches so that the front one, presumably NOW in the rear, NOW matches the REAR settings.  Odds are…FRONT has only fhe FURNACE DIP ON.  The rear is set to zone 3 and Furnace ON,  This is based on ONE Thermostat.  If you have TWO.  Bedroom will be Furnace ONLY…..as the default is Zone 1.   Middle will be Zone 2 on.  Don’t recall the Furnace setting….PROBABLY NONE…as your heat is Zone 4 in a buried.  If you need to find it....post and one of our Dynasty experts will assist.  That’s the drill. YOU MUST GET AN FF….otherwise a wiring problem.  Some folks have to reterminate the PHONE connectors.

You need to be familiar with the prints....m and learn to use them,

Use the SEARCH Function.  Use AIR.  Then click on EVERYWHERE.  Select FILES.  There are several Dometic related or helpful files. there.  I did it for another member on his "AIR" system...but the Dometic popped up as well.  Here is the results of the search.  Download what you need to learn and understand.

https://www.monacoers.org/search/?q=air&quick=1&type=downloads_file

NO POP QUIZ THIS TIME…skipping the “May the Force….” Tagline.

Keep us posted…

 

2007 Sig to Dynasty 5 Button AQUAHOT HVAC Layout.pdf

[vipeboy2000]

Thanks! I will check all that. Mine is the single thermostat.  I checked all the fuses in my bedroom closet and those are all fine.  Zero power to the thermostat . So I'm thinking I royally messed up the main control board in the front ac when I removed it to check/fix the phone connector port.  As after that, is when I got no power to the thermostat at all. Will update as I troubleshoot.  Thank you for the diagram. 

Also, would switching off the main battery cutoffs at my batteries cut off the 12v to the ac ? That plus disconnect from shore power should make sure things aren't hot right? 

Edited May 3 by vipeboy2000

[MyronTruex]

Just chased a problem on my Penguins.

As a test, take your thermostat in hand and go to the front AC, inside. There you should find the two phone type plugs with a coupler on each of them.

One goes to the thermostat, the other goes down the line to the next AC unit.

Unplug both of them, mark them if you think necessary. Then plug the thermostat into the one that is supposed to go down the line. You might not be able to tell which is which, so while you have both disconnected, connect your thermostat to one then the other.

The thermostat should light up if you have voltage coming down from the AC unit board.

The two dangling cables are basically identical, or parallel if you wish to think of them that way.

If the thermostat does not light up, go to the AC unit and measure the DC voltage on that three amp fuse. You can use the metal of the area around the housing for the ground of your meter.

You can actually start before that measurement by checking your DC input from inside the RV. The connector should be dangling from that bundle of wires the phone wires live in. Mine has a Molex connector. Should be the red and black wires.

IF you do not have DC voltage there, you must find the source as mentioned already. Mine is F16 on a fuse panel in my closet. It would be easy to overlook it.

Be sure you use a voltmeter or a test light on both sides of the fuse there. Check all of them if you do not have DC at the molex plug. It is easy to misread labeling and seems common to not have things diagrammed perfectly. 

One phone cable runs the DC and the control signals down the line to the next AC unit, where it is then paralleled to the next one  if you have a third one.

Learning as I went, I thought  the second AC unit would have 12 volts from the fuse panel and would run without the first AC unit online. My mistake, the thermostat would not light up and there was no voltage on the 3 amp fuse in the AC unit. 

There was a pair of wires with 12 volts on them but they did not power the same pins on the molex connector. I suspect this power is needed to send power to the heater when called for. 

In an emergency, I would have borrowed power from those wires and powered the Red and Black wires and connected my thermostat directly to see if the single unit would come alive.

Being fortunate enough to have my 5 button thermostat and my new Micro Air thermostat gave me some confidence and capabilities for troubleshooting. 

My problem happened the day we were going on a five day trip, using a hotel fortunately this time. So the problem was there when we got back. The front AC unit was running fine after replacing the three amp fuse that I had blown. 

Why I know about how the DC is applied is mostly due to shooting myself in the foot. After fifty years of diagnosing things both of my feet have been shot many times over. I really should get a purple heart. 

My thoughts were an intermittent coupler or  broken wire at the edge of the RJ plug, or a touchy connection. I tried to re-crimp the connector and things went downhill from there. The thermostat went dead, as in no light up on either thermostat. Hence, the blown 3 amp fuse and bandages on my feet. 

I'm fortunate enough to have cable testing tools and a really neat "break out box". This break out box connects the wires from the RJ Jack to flat pins where my voltmeter was able to test for the 12 volts that needs to go on down the line. I have other tools as well and  could have listened to the control signal but using the simple tester, all wires appeared ok.

While traveling I had a cable on order to allow me to test things along the way as well as bypass the thermostat control cable completely. I will provide a link for that cable. It is critical when you make a cable, or replace a connector, that you get the wires in the correct pins. It is very easy to reverse the things. The diagrams are in the manuals.

I use a high power magnifier and headlamp combination to inspect every connection. The RJ tester tells the whole story quickly and will show any reversed or pins that are not in their proper place. 

I hope I made this simple enough and is not "Clear as mud". 

My plans are to draw this up in a simple block diagram after recovering from the trip. Guess I better get to it today. There is a simple block diagram in the manuals but it does not go far enough into the weeds and the troubleshooting portion does not suggest using the thermostat right at the AC unit either. 

If you do not see DC voltages as described, you need to take the board out again and use a magnyfing glass to inspect all circuit traces. A tiny crack is hard to see so use a bright light and look closely. 

With the spare cable I'm posting a link to, you can go  directly on the roof and plug right into the RJ jack thus bypassing the cables inside. 

As usual, Toms' explanation is far more elegant than my simplistic approach, but hope my recent excursion helps add to the resolution. 

 

Cable

Amazon.com_ 25ft Heavy Duty RJ12 Silver Satin 6 Conductor 6P_6C Straight Wired Telephone Line Cord by Corpco _ Electronics.pdf

Example of breakout box

Example of inexpensive cable tester

Edited May 3 by MyronTruex
adding pictures

[vipeboy2000]

Thanks.  Mine has a molex as well.  It does seem that I'm not getting 12 v to the 3amp fuse in the unit.  I'll check the pins in the molex next.  Will any rj12 phone cable work to test the thermostat directly at the unit? And how can you tell which port is the one for the thermostat.  Both of them go into that sheathed bundle so I can't tell. 

[MyronTruex]

AC air conditioner block diagram.pdfThe ports are parallel, that is they should be identical. There is no where I can find in my diagrams that have much information. I just did some testing with the breakout box and determined there was voltage on two pins on both of the cables.

My previous post suggest disconnecting both of the RJ cables to do the test directly at the AC unit. There is likely a coupler that connects the short cable from the AC to the thermostat and one to the next AC unit. You should be able to connect to the cable that drops down from the AC unit without even buying a test cable. 

DO NOT grab or buy just any cable. You need to look closely at the diagrams of the pinouts. Holding the connectors next to each other with the locking pin on the bottom the wires should go to the same pins.

There are cables that could easily switch the positive and negative and blow a fuse. The data pins probably don't care but it is possible they are not allowed to be reversed. 

The amazon picture shows the connectors side by side if you can zoom in very close as a reference. 

Edited May 3 by MyronTruex

[Tom Cherry]

5 hours ago, vipeboy2000 said:

Thanks.  Mine has a molex as well.  It does seem that I'm not getting 12 v to the 3amp fuse in the unit.  I'll check the pins in the molex next.  Will any rj12 phone cable work to test the thermostat directly at the unit? And how can you tell which port is the one for the thermostat.  Both of them go into that sheathed bundle so I can't tell. 

Followup….

First, you will have to go to the drawings and MAYBE start looking at the Pins and the “input” and output side.

@Frank McElroy is our expert on the Dynasty….he has a 2008.  PM HIM.  Odds are he KNOWS exactly which fuse provides the power 

NOW….Myron has given you a lot of help.  BUT….your question is a little “higher level”.

The system, per Dometic design, is configured or “designed” for ONLY one 12 VDC point.  To state another way.  For each group or “section”….you only need ONE of the Control Modules…..wihich is on the Dometic breakdown as “AC Board” or something like that.  BUT, Monaco, chose to run a hard 12 VDC power line to every HVAC Unit.  That is a HARD AND FAST RULE. If I understand your problem…you have no 12 VDC to the front….that is a SINGLE control or single UNIT.  

NOW the rear is a little different…..read and UNDERSTAND this.  The 12 VDC to the front AC is the same “feed” or FUSED  circuit as the rear.  Your rear is a bit tricky.  12 VDC goes to the Rear (Zone 1) and Middle (Zone 2).  BUT THEN…Monaco broke their LOGIC or maybe CHEATED.  There is a Hidden, standalone AC Board buried….it does NOT, per Frank’s digging, a SEPARATE 12 VDC.  It works as ….HEY, here is my Data Communications cable….it gives me 12 VDC on ONE Pair.  I get my Digital MPX command signal from the OTHER Pair.

From a practical or troubleshooting plan, this is HOW I’d DO IT.

Does the REAR Thermostat have Power?  YES….YEA! I didn”t blow the house FUSE….and I know the issue is in the FRONT…

if NO!…the Thermostat is dead.  STOP any further chasing and FIND the HVAC fuse.  It IS on the House Board.

Also, since Myron is an advocate of simplicity…..start reading page 105…it has all I just, in both posts, said and explans howeach zone works.  IT IS NOT a trouble shooting guide….but unless you know the basics….as Myron does…his issues and such and his innate knowledge may not be adequate to help you.

NEXT UP…read section 8.  BUT, the Dynasty does NOT have the “panel” labels in the manual  if yours is missing, all the labels are shown in the print. BE AWARE…you may NOT have an HVAC FUSE LABEL.  My HVAC fuse is labeled “SATELLITE”.  No WHERE is that also shown as HVAC….except in the prints.

NEXT UP.  Here is what I would do….and this ASSUMES that you have found the fuse and have POWER to the rear Thermostat…..BTW…this answers the “HOW TO TEST”.  Look in the trouble Shooting guide….or download the manual for your unit,  towards the back there is section on “how to wire and install”.  Find the Ground and PLUS 12 VDC to the “AC Board”.  I THINK…and wager that the pins or the RJ connector leads, are on the print.  So…VOM on continuity…..use the GROUND connection and then check each of the 4 Pins.  THEN do the same for the 12 VDC…those two PINS are the power.  Members hace pinned out the RJ many  times before.  Think you messed yours up?  Go to the roof and pull the cover off the rear.  Pin out all 4 leads….then see if you have the same upfront. If you fried the board…then the Data Cable will not work.  You CAN swap boards or move the thermostat…..as Myron did.  

BTW….the leads are INTERCHANGEABLE.  The Data cable can come into the Zone 1 rear….to the Thermostat….and the other one goes to the Zone 2.  You can SWAP the cables.  Domietic did that for ease of installation….the Controller is basically a “Parallel” connection….so the two dangling RJ’s will work on either cable,

That’s the way….from knowing the system and helping at least 50 - 100 folks, like yourself, troubleshoot….once you have the basics of how it works,,,,testing is easy.

Good Luck…

 

[vipeboy2000]

1 hour ago, Tom Cherry said:

Followup….

First, you will have to go to the drawings and MAYBE start looking at the Pins and the “input” and output side.

@Frank McElroy is our expert on the Dynasty….he has a 2008.  PM HIM.  Odds are he KNOWS exactly which fuse provides the power 

NOW….Myron has given you a lot of help.  BUT….your question is a little “higher level”.

The system, per Dometic design, is configured or “designed” for ONLY one 12 VDC point.  To state another way.  For each group or “section”….you only need ONE of the Control Modules…..wihich is on the Dometic breakdown as “AC Board” or something like that.  BUT, Monaco, chose to run a hard 12 VDC power line to every HVAC Unit.  That is a HARD AND FAST RULE. If I understand your problem…you have no 12 VDC to the front….that is a SINGLE control or single UNIT.  

NOW the rear is a little different…..read and UNDERSTAND this.  The 12 VDC to the front AC is the same “feed” or FUSED  circuit as the rear.  Your rear is a bit tricky.  12 VDC goes to the Rear (Zone 1) and Middle (Zone 2).  BUT THEN…Monaco broke their LOGIC or maybe CHEATED.  There is a Hidden, standalone AC Board buried….it does NOT, per Frank’s digging, a SEPARATE 12 VDC.  It works as ….HEY, here is my Data Communications cable….it gives me 12 VDC on ONE Pair.  I get my Digital MPX command signal from the OTHER Pair.

From a practical or troubleshooting plan, this is HOW I’d DO IT.

Does the REAR Thermostat have Power?  YES….YEA! I didn”t blow the house FUSE….and I know the issue is in the FRONT…

if NO!…the Thermostat is dead.  STOP any further chasing and FIND the HVAC fuse.  It IS on the House Board.

Also, since Myron is an advocate of simplicity…..start reading page 105…it has all I just, in both posts, said and explans howeach zone works.  IT IS NOT a trouble shooting guide….but unless you know the basics….as Myron does…his issues and such and his innate knowledge may not be adequate to help you.

NEXT UP…read section 8.  BUT, the Dynasty does NOT have the “panel” labels in the manual  if yours is missing, all the labels are shown in the print. BE AWARE…you may NOT have an HVAC FUSE LABEL.  My HVAC fuse is labeled “SATELLITE”.  No WHERE is that also shown as HVAC….except in the prints.

NEXT UP.  Here is what I would do….and this ASSUMES that you have found the fuse and have POWER to the rear Thermostat…..BTW…this answers the “HOW TO TEST”.  Look in the trouble Shooting guide….or download the manual for your unit,  towards the back there is section on “how to wire and install”.  Find the Ground and PLUS 12 VDC to the “AC Board”.  I THINK…and wager that the pins or the RJ connector leads, are on the print.  So…VOM on continuity…..use the GROUND connection and then check each of the 4 Pins.  THEN do the same for the 12 VDC…those two PINS are the power.  Members hace pinned out the RJ many  times before.  Think you messed yours up?  Go to the roof and pull the cover off the rear.  Pin out all 4 leads….then see if you have the same upfront. If you fried the board…then the Data Cable will not work.  You CAN swap boards or move the thermostat…..as Myron did.  

BTW….the leads are INTERCHANGEABLE.  The Data cable can come into the Zone 1 rear….to the Thermostat….and the other one goes to the Zone 2.  You can SWAP the cables.  Domietic did that for ease of installation….the Controller is basically a “Parallel” connection….so the two dangling RJ’s will work on either cable,

That’s the way….from knowing the system and helping at least 50 - 100 folks, like yourself, troubleshoot….once you have the basics of how it works,,,,testing is easy.

Good Luck…

 

Thanks! So there is a hidden rear thermostat? or are you saying on yours there is.. My single thermostat controls all 4 zones in ours. I believe i found the a/c control fuse, tied in with my bedroom ceiling fan and doorbell.. that fuse and all the other fuses are fine in my bedroom wardrobe panel, FRB and RRB. 

Good to know that the connections for the data /therm cables don't really matter. Thanks!

So I  THINK I have narrowed it down to either damaged front board or somehow the thermostat... I will check power going to the board either tonight or tomorrow.. Have downloaded and read and will re-read all those troubleshooting documents many many times as I go through each item this weekend. I do have one control board and a new Micro air thermostat on order as well to cover my bases (hopefully they arrive soon) 


Thanks guys so much. 

[Tom Cherry]

48 minutes ago, vipeboy2000 said:

Thanks! So there is a hidden rear thermostat? or are you saying on yours there is.. My single thermostat controls all 4 zones in ours. I believe i found the a/c control fuse, tied in with my bedroom ceiling fan and doorbell.. that fuse and all the other fuses are fine in my bedroom wardrobe panel, FRB and RRB. 

Good to know that the connections for the data /therm cables don't really matter. Thanks!

So I  THINK I have narrowed it down to either damaged front board or somehow the thermostat... I will check power going to the board either tonight or tomorrow.. Have downloaded and read and will re-read all those troubleshooting documents many many times as I go through each item this weekend. I do have one control board and a new Micro air thermostat on order as well to cover my bases (hopefully they arrive soon) 


Thanks guys so much. 

Too much verbiage….  My fault.  Each system is unique.  The manual shows TWO thermostats.  OK….you got ONE.

SO…simple.  Data cable starts at the Thermostat. Runs to the front.  Then, presumably to the middle.  It MAY loop down into that rabbit hole called Zone 4….then back to the Bedroom.  The HIDDEN device is a Standalone Controller. There is NO HIDDEN THERMOSTAT….just a BURIED Controlled. There will be THREE “wall” or under counter “REMOTE TEMPERATURE SENSORS.  The front Thermostat is USUALLY the one for the front.  Now JUST TO DRIVE YOU CRAZY….SOME Patriot Thunders ( a Dynasty Clone)….actually had an UP FRONT remote temp sensor….so the MAIN Thermostat got a reading from each one.

OK….now be ready to learn SOME MORE.

If you call Dometic and say….HELP ME….it don’t work….then tell them you do NOT have a complete Dometic system….as in the OEM 5 Button Thermostat….they will say.  Sorry…..we only offer help for a Dometic system.

Call MicroAir….tell them NO WORK.  Sorry, we do NOT know or provide help on a NON FUNCTIONAL Dometic control system.  Your existing Dometic system MUST be functional.  YES… I called and asked….  We have had Members that had a MicroAir.  One unit failed.  The MicroAir folks said….send back (still under warranty).  The member was sharp enough and followed the help here.  OPPS.  He had a FAILED controller.

NOW, that you have given out MORE information….I would proceed as follows.

Remove the Thermostat.  You’re gonna replace it anyway or maybe NOT.  ASSUMING you have power to the fuse….and we don’t know that.  Here is the way.

Go UP TOP….rear UNIT.  Follow the wiring.  Find the INCOMING 12 VDC.  MEASURE and VERIFY that you have 12 VDC there.  Then unplug, downstairs, both cables.  Mark the mating ones if you want….does NOT matter.

Then….Plug in the Thermostat to any of the two CONTROLLER cables (NOT the ones connecting the zones.  NOW reset the Thermostat per instructions.  If it WORKS…..NOT A THERMOSTAT issue. 

OK….keep going.  Pull the control unit out,  take it to the front. Take a picture of the DIP switches….and set the REAR ONE just like the Front.  Go downstairs.  Plug in the Thermostat like in the rear.  If it works….bad controller. IF NOT….something is wrong in the AC unit…and if you can’t figure it out….call or get a tech.

You have to isolate which component is bad….and until you do the above, you are guessing as well as getting frustrated.

Texted you and will help off line

 

r

[MyronTruex]

Remember, just because a fuse looks good, you need to measure voltage on each end while it is in circuit. Check your bedroom fuse panel with a voltmeter.

I discussed my two unit system. The front is the zone 1 on mine. There is 12 volts fed to the molex pin on it. There is NOT 12 volts fed to the rear molex plug on AC zone 2.  There is 12 volts on the blue wires on both of the AC units. This feeds my furnaces.

The 12 volts goes through the molex, into the RJ plug, into the AC control board and there it supplies power though the 3 amp as far as I can tell. If the 3 amp fuse is popped, the thermostat is dead. Does not light up.

Taking the thermostat in hand to the rear one and plugging it in directly it did not light up. I found there was no voltage on that 3 amp fuse in AC unit 2 without the RJ cable bringing voltage to it. So there is no voltage getting to the circuitry needed in my rear one. Until the RJ cable feeds it. So in order to operate my rear ac in an emergency I would have to run power to that molex plug to get the thermostat to power up.

Hope this is clear and simple. 

IF your front AC is the first in line, it needs 12 volts. Until you get that voltage there you are spinning your wheels. 

 

[Dr4Film]

I use this to test all of the AC cabling to make sure there is proper communication.

https://tinyurl.com/7pc78hn8

[vipeboy2000]

Thanks so much everyone.  New control board in the front fixed the communication issue and found a burned fuse I somehow missed the first 4 times.  Chatted with Tom directly.  Very helpful.  

Using the old dometic 5 button thermostat until the next issue! 

Edited May 5 by vipeboy2000

[MyronTruex]

Great. Where was that fuse located? Did you use a voltmeter to test it or just visual? 

 

[vipeboy2000]

In the wardrobe.  One I had pulled out to test and check earlier but i swear it wasn't burned then ha.  F5 ot f6 I think marked as bedroom ceiling fan.  

Edited May 5 by vipeboy2000

[Tom Cherry]

4 hours ago, vipeboy2000 said:

In the wardrobe.  One I had pulled out to test and check earlier but i swear it wasn't burned then ha.  F5 ot f6 I think marked as bedroom ceiling fan.  

Remember….good ole Monaco never marked, at least on the folks I have helped, the fuse to the Control Boards or “AC Board/Panel as HVAC.  Satellite…ceiling fan…you name it. Unfortunately on the Dynasty prints, you have to check mating connector prints and look for HVAC such…then….you start to trace that particular “PIN” or pins…once you find that print…then you follow that harness to where it mates up or is hooked up and then get the fuse number.

NOW….that is true for Camelot’s and Dynasties.  The Wire is easy to trace on the Camelot (and Diplomats and such),  Dynasty uses the pin and connector logic and not a pure “schematic”.  Older Dynasties and Windsors and such MAY have conventional schematics.  There was two GROUPS or schools in Monaco….and you never knew WHICH “format” or convention or system that was used.  For those like me that works with tracing a wire….my prints are fine.  Others that understand the connectors and pin and how to trace find the Dynasty easy to work with….the Dynasty challenges me….but I am learning….

[Tom Cherry]

On 5/3/2024 at 10:03 PM, MyronTruex said:

Remember, just because a fuse looks good, you need to measure voltage on each end while it is in circuit. Check your bedroom fuse panel with a voltmeter.

I discussed my two unit system. The front is the zone 1 on mine. There is 12 volts fed to the molex pin on it. There is NOT 12 volts fed to the rear molex plug on AC zone 2.  There is 12 volts on the blue wires on both of the AC units. This feeds my furnaces.

The 12 volts goes through the molex, into the RJ plug, into the AC control board and there it supplies power though the 3 amp as far as I can tell. If the 3 amp fuse is popped, the thermostat is dead. Does not light up.

Taking the thermostat in hand to the rear one and plugging it in directly it did not light up. I found there was no voltage on that 3 amp fuse in AC unit 2 without the RJ cable bringing voltage to it. So there is no voltage getting to the circuitry needed in my rear one. Until the RJ cable feeds it. So in order to operate my rear ac in an emergency I would have to run power to that molex plug to get the thermostat to power up.

Hope this is clear and simple. 

IF your front AC is the first in line, it needs 12 volts. Until you get that voltage there you are spinning your wheels. 

 

Good point.  Monaco was usually consistent….but also sometimes NOT.  Most of the prints I pull for the 12 VDC and AC and the Data Communications connections will have 12 VDC to every control module or the “AC Board” as Dometic calls it.  Frank showed me the NOTE in the “installation” verbiage…only ONE control module needs 12 VDC.  So, Monaco gets an attaboy for redundancy.  But Frank’s 2008 hidden controller for zone 4 that supplies the middle section heat violates that redundancy.  NO 12 VDC….gets it from the Data Communications Cable run.  Go figure….always use the prints….but verify…. 

Myron, have you found or looked at the print for the 2002 Windsor.  Again. I fall into the trap of thinking that all were done the same….as in the 12VDC was a hard and fast rule to every HVAC unit….

 i have not got a good, I think, 2002 Print for it.  Never saw it in the scanned manuals….so I use others or go up and down a year.  That would be good to know. You are spot on. If Monaco cheated or if some assembler didn’t hook up or pulled the wrong cable and you don’t have the usual 12 VDC line….like to the front….problems. Unfortunately some of the “supposed to be there” wires got lost in the run.  This would not be the first time that a MUST BE HERE wire was not….we have seen this, unfortunately, too many times before….

Thanks,

OK…a side note.  Monaco did get cheap.  The Intellitec EMS HVAC Relays were SUPPOSED to switch ON and OFF the 12 VDC to every HVAC.  That is the way it was designed.  Monaco would NOT run the 12 VDC from the EMS Board….don’t ask….nobody knows. BUT then they uses the low voltage switching relays for a pure..FLA AC Current method.  Ever wonder why the EMS Boards fail??  YES, supposedly from the original owners that talked to to the engineers at rallies and shows and to the techs at the warranty centers.  Monaco knew FULL well that the 12 VDC was supposed to be switched.  OPPS….the Dometic systems were ever designed for using SWITCHED 12 VDC.  Run power to one….they all got it.  My only supposition was that each HVAC unit would have had to have a separate 12 VDC relay.  Thus the EMS would energize or kill the 12 VDC.  But then the positive from the data communications cable would have to have been “cut” for every HVAC unit….and fed or abandoned.  Then the 12 VDC going to each control module would have come through each relay…. Talk about a major abortion.

The OTHER solution….run a second 12 VDC line to each HVAC unit.  Put a 12 VDC coil on a relay rated for 20A FLA.  or maybe higher as the start up current would hit the mid 20”s.  The Thermostat on most home systems turn on 220 VAC…but the control board are not ON..  so, in this case….maybe a 30A FLA contact rating.  Then the EMS would shed properly and the HVAC relays were running at fhe right voltage and load.

NEVER HAPPENED….very few know this….and we often have folks that have that “AHA” moment when they source a relay and fix an Intellitec EMS. A case where the MPX control was NOT suited for the EMS and Monaco cheated….now you know….if you read this far and care….folks usually don’t until the EMS board fails…..

[MyronTruex]

5 hours ago, vipeboy2000 said:

In the wardrobe.  One I had pulled out to test and check earlier but i swear it wasn't burned then ha.  F5 ot f6 I think marked as bedroom ceiling fan.  

Hence my suggestion of using a test light or voltmeter while the fuses are in place. Find a good ground and touch each end of the fuses. The blade fuses have a tiny slit on top of their foot/leg so you don't need to get to the actual fuse socket. 

Over the years I have had my chops busted when a fuse had a hairline crack, or opened up under load, or I added to the issue by not putting the fuse back in place correctly. That is missing one leg of the fuse connection, thus my previous comments about shooting myself in the foot. A pointy cheap 12 volt test light that has a bulb inside is perfect for poking about fuses.

However, never poke about wires under a dash, as you can set off air bags and the results can be costly and even deadly. The last time one of my techs did this it cost 4K to replace the windshield and air bags. He still worked for me after that. I told him I just spend 4K on his education. 

[vipeboy2000]

I did run through every fuse with a multimeter while they were in place .. and even pulled the ones I thought could be related .. but obviously .. I missed it somehow the first couple times lol .  Anyway , thanks for the assistance.  😀 we will have ac for the beach this week so we are ecstatic. 

[Dr4Film]

@Tom Cherry

I can speak for my previous 2002 Windsor (which is now owned by @Lenny D) but it may not be the same for all 2002 Windsors as mine has the Aqua-Hot System.

My AC control is located in the bedroom with Zone 1 being the rear bedroom AC area and Zone 2 being the front Living area AC. The data cable runs from the Thermostat to the rear AC first then is daisy-chained to the front AC where it stops. I never searched where the 12 VDC comes from but it has to be either from the front or rear AC wiring. There are a bunch of wires stuffed into that opening both in the front and rear.

The Dometic AC Thermostat does NOT control any of the Aqua-Hot zones. The AH has three different zones all with their own separate thermostats, one in the bedroom, one in the bathroom and a third in the hallway near the kitchen.

Now @jacwjames also has a 2002 Windsor but does not have the Aqua-Hot so his could very well be wired differently.

Edited May 5 by Dr4Film

[jacwjames]

27 minutes ago, Dr4Film said:

 

My AC control is located in the bedroom with Zone 1 being the rear bedroom AC area and Zone 2 being the front Living area AC. The data cable runs from the Thermostat to the rear AC first then is daisy-chained to the front AC where it stops. I never searched where the 12 VDC comes from but it has to be either from the front or rear AC wiring. There are a bunch of wires stuffed into that opening both in the front and rear.

 

I have a fuse for the front & rear AC's in the bedroom 12 volt fuse panel.    F19  15 amp fuse

[Dr4Film]

6 minutes ago, jacwjames said:

I have a fuse for the front & rear AC's in the bedroom 12 volt fuse panel.    F19  15 amp fuse

My 02 Windsor has the same fuse but I never searched its routing path, whether it goes to the rear AC or Front AC or possibly it goes to both locations.

[Tom Cherry]

3 minutes ago, Dr4Film said:

@Tom Cherry

I can speak for my previous 2002 Windsor (which is now owned by @Lenny D) but it may not be the same for all 2002 Windsors as mine has the Aqua-Hot System.

My AC control is located in the bedroom with Zone 1 being the rear bedroom AC area and Zone 2 being the front Living area AC. The data cable runs from the Thermostat to the rear AC first then is daisy-chained to the front AC where it stops. I never searched where the 12 VDC comes from but it has to be either from the front or rear AC wiring. There are a bunch of wires stuffed into that opening both in the front and rear.

The Dometic AC Thermostat does NOT control any of the Aqua-Hot zones. The AH has three different zones all with their own separate thermostats, one in the bedroom, one in the bathroom and a third in the hallway near the kitchen.

Now @jacwjames also has a 2002 Windsor but does not have the Aqua-Hot so his could very well be wired differently.

Well NOW….isn’t that interesting….here is my take on it.  And you might have just offered a good insight….

OK…your PREVIOUS Windsor,  Myron has stated…..and he is a great tech….no 12 VDC to rear.  Comes in on the front.  The control module distributed the 12 VDC back to the thermostat.  It also sent it the other way to the rear.  Maybe…pure speculation….Monaco used the ONE WIRE 12 VDC feed.  That is all, and this has been tested, that is needed.  It also squares with the installation instructions.  It works.  Myron is right.  If you LOST the 12 VDC pair in the Data Communications Cable….then, you would lose the unit.  NOW…run a hot wire or 12 VDC to the rear.  First….reset to factory…..get an FF.  At that point, then the OTHER 2 pair is running the MPX.  Since the rear has 12 VDC….then a faulty data cable (open in the 12 VDC) will work….but only if the MPX pair is OK.  That is how I UNDERSTAND and from the manuals and also folks here and helping troubleshoot.

NOW…as to the PREVIOUS Aquahot in your Windsor.  My “knowledge base” is for a model or two newer…but if I assume that the control boards look similar…maube not as many zones, but similar, Richard, to your 06 Dynasty…here is how it would (should have worked).  Each individual thermostat was only an ON/OFF unit.  Totally MECHANICAL….not powered.  When the temp dropped below the set point….say set was 70 and it dropped to 67, the mercury containing bulb, had two WIRES in the “drop” or mercury.  Same as turning on a wall switch,  the thermostat was “calling” for heat.  Once the temp hit 70….the mercury in the thermostat only had ONE wire….in it.  Like turning off a light switch.  The newer AH boards have TWO Terminals or WIRES for a “thermostat” connection.  There is NO DC or whatever.  Use a paperclip and jumper….the pump starts and the blower (for that zone) starts.  

Fast forward to your 2006 Dynasty.  I’m…SPECULATING….Monaco eventually did do the belt and suspenders….and ran 12 VDC to every AC control module.  Why Frank’s Dynasty had none???  Ask the engineer.  The PRINT does not show it….I think….and it ain’t there.  I don’t have my laptop on vacation so the 25 sets of model year wiring diagrams I downloaded aren’t with me….I’m on my IPAD.

OK…Richard, here is how your system works….I will NOT go down the hidden controller or ZONE 4.  BUT…. If you have TWO thermostats or one….it works this way.  Each Zone controller has a FURNACE DIP switch.  If one ZONE or any ZONE shows FURNACE or HEAT….that controller’s DIP is CLOSED…..that is how it works.  If you had the NO AQUAHOT version.l..there is a front and rear furnace,  the Front zone has HEAT/FURNACE.  The controller closes a dry set of wires….they run to a furnace control board…like a light switch…it comes on,

In your case, wherever or whatever ZONES has a HEAT or FURNACE option….there is ONE pair of wires going to a particular zone on the AH control panel.  As I said…jumper those two screws…paperclip….the pump and fan come on.

In the 07 Dyansty and up….Monaco added a “hidden Module”.  In the owner’s manual….there is a chart that shows the zone numbers….which thermostat….if dual and which zone where the heat works.  The MIDDLE ZONE, on the 07 & higher….have a special ZONE for AquaHot or HEAT.  There is a standalone controller….when you set whichever zone for the middle to HEAT….the hidden controller….with a remote temp sensor….takes over and turns ON or OFF the circuit for heat.

That is the way it is wired…..they way it works.

NOW…Frank and I helped a very astute tech that had installed his own new Dometic units and the Dometic CCC2 thermostat(s….may have been two).  He had NO AC in the middle.  Finally, we got an update.  He had some how “pushed or tucked” the two outgoing wires to the AH under something or whatever.  He communicated that it WORKED before….not NOW.  Had to be a DOMETIC problem.  He “lost” the AH wires.  He insisted….MONACO left them out.  Now…there is NO WAY it would have worked before….  In his install, he lost them….and did it up right…but was also extremely confident….he made no mistakes.  After a while….he went back….maybe to try to “PULL” the wires that Monaco forgot.  OPPS….he had buried them….hooked them up.  NOW IT WORKS.

That is NOT uncommon….techs do it…novices do it…I’ve lost a wire….we all can “do it”.  But….if you rely on the prints….and it worked before….it has to be operator error.

This is a simple or complex system,…based on your skill and experience.  Our goal, as moderators….help folks understand….and that is what Daniel is starting to absorb. I think it took me at least 3 years just to begin to learn about the MPX and I had installed Home systems and troubleshot….now, I learn or confirm, from each topic…

NEVER KNEW that the 2002 AH had separate Heat Thermostats….THANKS!,
 

[Dr4Film]

@Tom Cherry

Yes, my 06 Dynasty is completely different. There are currently two Dometic 5 Button CCC's which do ALL of the heating & cooling controls for the coach. The rear AC is a newer Penguin II but they installed a converter board into it so it would be compatible with the 5 Button CCC. I have the new board tucked away which will go back in when the other two AC's get updated to Penguin II's.

The rear CCC controls all of the functions for the Rear AC and the Middle AC. The Front AC has its own 5 Button CCC.

When the time comes I will eventually upgrade to Micro-Air Thermostats once all of the AC's are the same.

[Tom Cherry]

3 minutes ago, Dr4Film said:

@Tom Cherry

Yes, my 06 Dynasty is completely different. There are currently two Dometic 5 Button CCC's which do ALL of the heating & cooling controls for the coach. The rear AC is a newer Penguin II but they installed a converter board into it so it would be compatible with the 5 Button CCC. I have the new board tucked away which will go back in when the other two AC's get updated to Penguin II's.

The rear CCC controls all of the functions for the Rear AC and the Middle AC. The Front AC has its own 5 Button CCC.

When the time comes I will eventually upgrade to Micro-Air Thermostats once all of the AC's are the same.

Sounds like a plan to me.  You got it.

My approach would be the same for my Camelot….except…one dead soldier….NEW ARMY.

Now….this is MY OPINION….and my circumstances and my “skill set”. I am going to pay my trusted tech to do it….I could do it…but I fix things that are more complex and don’t have anyone to help with the toting and lifting…..or a good helper.

NOW….having said that…I know a lot more about the ins ans out and MPX “uniqueness” than he probably does.  I know that if trouble occurs….and Imhave the complete Dometic package, the Dometic dealer tech support will assist him.

IF there was a “BLACK BOX” tester that one could hook up on an install and then get idiot lights or whatever….that the RJ Data Cable to the thermostat is “working”….and he had one….then i MIGHT consider the MicroAir.  Since I have personally talked to tech support at Dometic, MicroAir….and also Coleman to see about making a RecPro work…. I don’t want to have to start changing control modules and such.

My ONLY criticism of MicroAir….other than not knowing the reliability of their units.  Their design engineers know way LESS about how a Dometic system works than most who read and learn here.  They just “tore apart” the 5 button and 10 button and fed it data on a bench and then cloned the functions.  They have NARY a clue as to what happens on the other end….all they know is how to send a coded signal.  NOW…maybe, like Frank did for the Kong’b….the circuit designers bought the control modules and breadboarded up a system.  OK….that’s how they did it,

BUT…the two techs….in 2 separate phone calls said….we do not “understand” how the MPX works.  We know that our units, regardless of type or vendors, will interchange.  We do NOT, at our level, know how nor will we trouble shoot.  The requirements are that the owner must have a reliable and functional downstream system….or in your case….a Dometic system…. CC CCC or CCC2.  Thanks for calling.

We have already had issues where the folks here fixed or identified the issue….a bad Controller and MicroAir was clueless….but would ship a replacement…. Sort or like you having a big hole in an aluminum wheel…tire will not hold air.  You don’t know it.  The tire shop gives you a new tire….but don’t know how to test.  YES…my warped logic….but, if it is all Dometic….no finger pointing and a source for fixing.  Maybe a tech might…but techs seemed to be “stumped” more and more and don’t want to work on our legacy units.

I watched a tech use a laptop and install some gee whiz complex upgrade to a high dollar rig.  He knew it all or was on the phone and ran the diagnostic.

BUT…asked a question about a simple amps and volts issue on a hydraulic unit…said….you need a new unit….we don’t really troubleshoot… Mobile techs are the same.  Been in caravans and the techs installed new parts until it worked…

MY OPINION….others will differ…