New Dometic ACs and Stat but now no heat in bathroom

[Pduggs]

No.
 

The Motorcoach Store tech knows nothing about the hidden zone 4 controller. I emailed them a pic of it, but they claim it’s not necessary. They are now suggesting something is wrong with my AquaHot pump. Thus not their responsibility. Same old story with RV repair shops. 

I plan to call Dometic again to see if they can get me the correct control board. 

9 hours ago, Tom Cherry said:

YES…they WILL be different. .you need to look at your prints.  The AquaHot Zones in no way, rhyme or reason match the Zones on your thermostat.  The Heat or AH print is quite explicit and you can trace the HVAC zones directly to AH control panel. Just follow the thermostat line from each HVAC zone. 

Once you have that solved, the the next trick is to take the leads (thermostat wires) from a zone that is working….you can control it and you get heat.  Then pull the leads from the zone that does not work (Zone 2…I think…but verify).  Then use the thermostat that is working to bring one the errant zone,  IF a that works, you have an issue with the thermostat or more correctly, the HVAC controller that is supplying the signal or is supposed to,  if it does NOT work….then the issue is in the AquaHot system.

That is the easiest way to test and isolate WHY. 

What I’m not sure of or did not understand…If you have control or can turn on the errant HVAC Zone and the blower in the zone works, then you DO have have an AquaHot issue,  all the HVAC controller is doing is closing a set of contacts.  In reality, you could use a bent paper clip on each pair of the AquaHot “Thermostat” terminals.  What that does is then turn ON the appropriate pump.  The pump contacts are internal and controlled by the main control board.  There is a set of “Blower”or fan terminals.  These terminals go to the fan register(s) for that zone.  The board has a set of pump wires or terminals to control the right pump.

That, in a nutshell, is how it works….

Regardless, as Frank said, you MUST have the right control board for the fourth zone.  Your old zone ain’t gonna work.  You really need to find the print and study this and understand it.

 

 

One would think when you pay over $8k for the installation of three new AC units at a high end RV service shop, that shop would know how to do the job correctly. Instead, I get excuses. 

[Tom Cherry]

4 minutes ago, Pduggs said:

No.
 

The Motorcoach Store tech knows nothing about the hidden zone 4 controller. I emailed them a pic of it, but they claim it’s not necessary. They are now suggesting something is wrong with my AquaHot pump. Thus not their responsibility. Same old story with RV repair shops. 

I plan to call Dometic again to see if they can get me the correct control board. 

One would think when you pay over $8k for the installation of three new AC units at a high end RV service shop, that shop would know how to do the job correctly. Instead, I get excuses. 

Frank is the expert and I learned a lot from him...  Here is the print you need.  Look on it and you will see ZONE 4 A/C Brain.  That is what controlled the AH in your old system. You need to locate it.  Frank can tell you where he found his on his 2007 Dynasty.....probably the same place.  Once you locate it, get the DuoTherm Part number and then contact Dometic.  The 0701932 PN didn't turn up any useful hits in google.  BUT, that is what is missing. That PROBABLY was an old Monaco Replacement part number....so what is on the BRAIN is what you need.

There is, I BELEIVE, a new "Smart Brain" that must be used with the new thermostat.  That is what you want...  Then you can talk to Dometic with some intelligence....

NOW, that print also shows which HVAC Zones control which AH Zones.....as you can see....the "Zone" numbers are like Venus and Mars....they do NOT match....so that is a wild goose chase.

Hope this helps....and YES....it is Disheartening to know that a high end shop was NOT smart enough to know this.  However, in their defense, the use of a hidden ZONE or brain was typically NOT an issue on the lower end Monaco's.  I have a 2 AC unit and have helped folks troubleshoot and fix their control issues on their 3 AC systems....which do NOT have the hidden Zone 4 Brain....  This is unique....to say the least.  BUT, it can ONLY be fixed by replacing the OLD BRAIN with a NEWER and SMARTER BRAIN.  The wiring should be simple.  You unplug ONE and PLUG in the new one.  There are ONLY TWO phone lines and a hard wired (2 terminal) Temp Sensor and two wires to the Aquahot.  You just read the instructions and it is finished.  I would download the manual for the existing unit.  Then you have the terminal layout for the Remote temp sensor and the furnace (AH) wires.  Then the new unit has the instructions.  Move 4 wire and hook up 2 phone cords.

It really is as easy as that....   

 

 

38071413 (Schematic, Dual Heat Elements, Aqua-hot).pdf

[Pduggs]

Thanks Tom. Frank did tell me about the hidden circuit board or “brain.”  Here is a pic of it. Part number is similar to that on the schematic you sent. I’ll call Dometic today. 
 

I don’t want to be unjustly harsh on the folks at The Motorcoach Store, but I’d have thought they’d know this. Is Monaco the only coach maker that used this design?

[Tom Cherry]

1 hour ago, Pduggs said:

Thanks Tom. Frank did tell me about the hidden circuit board or “brain.”  Here is a pic of it. Part number is similar to that on the schematic you sent. I’ll call Dometic today. 
 

I don’t want to be unjustly harsh on the folks at The Motorcoach Store, but I’d have thought they’d know this. Is Monaco the only coach maker that used this design?

Get the part.  Install it yourself or fuss at them.  I have NO idea how many other MH's have this hidden brain.  BUT, for whatever reason, The 2007 Dynasty and UP and your 2008 have it.  PROBABLY the 09 through 12 or so when Rev took over killed the Roadmaster chassis.  You now have the print.  The dealer should have known about this.  They were totally off base and could have had you do troubleshooting and possibly damage your AH .

SO....you decide how to go from here.  You MIGHT need to be able to email or text a copy of the print to Dometic when you talk to them....just to be sure....as well as the picture and also your NEW Thermostat.  They SHOULD easily be able to help...but if this was a little known Monaco revision, all their techs might not be up to speed.  SO, showing them the 4th zone....that is good.

You WILL have to make (assuming it is like the one you pull out) two DIP switch settings.  Furnace DIP on.... and Zone 4 Switch On....that tells it what is going on and then you do a complete reset of the system (read the manual for the new system).  That should do it.

Good Luck...

[Pduggs]

I spoke with Dometic. They tell me this is the part I need. They referred me to Amazon to purchase. They weren’t familiar with my set up and didn’t sound very persuasive that it is right. Anyone have any thoughts on whether this is the right part?
 

My mistake. The above pictured part is not the part Dometic suggested. It’s this one. I couldn’t find it on Amazon. 
 

[Tom Cherry]

With all due respect, this thread is approaching the point of Moderator’s Shut Down.  The issue is simple and has been regurgitated several times and Frank McElroy has, in a PM, sent you the correct part number (3312020].   He also provided the link for purchase.

https://parts.unitedrv.com/products/dometic-comfort-control-center-ii-multi-zone-kit-control-box

Your installing dealer was not totally qualified to complete the installation and erroneously is blaming the issue on your AquaHot.  That is not the problem.  You must replace the existing zone 4 controller with the one above.  Your also need to understand the difference in the two pictures you posted. The top picture from Amazon is the same and correct Part Number that Frank provided.  The lower picture says OEM.  It is the actual control board that comes with the controller or inside the enclosure in the Amazon picture.  Thus if you purchased it, you would need to mount it in a similar enclosure and also the instructions would be missing as to which wires go where and such.

BTW.  The exact PN IS 3312020.000…..which is what is in both the Amazon and Frank’s link.  You might want to Google.  The lower cost STOCK RV parts like pumps and such on eBay and Amazon might NOT come with full warranty.  We have had these issues before.  Purchasing is recommended from an “authorized” dealer or distributor. You might want to verify that the Amazon is not a third party reseller….just passing that on.

You can advise the dealer and have them replace the zone 4 controller with the new, compatible with your CC2 (memory) Thermostat.  it will need to be configured and then your CC2 Thermostat reset so that the thermostat recognizes the addition of the 4th zone.

The other option is to install it yourself.  Generally speaking and also talking to Frank, there is NO DC power required…and I do not think you will final a power lead, but this is Monaco, so reinstall if there.  Configure the DIP switches.  #1 & #4 should be on, like the old one.  1 for Furnace (means there is one being controlled) and 4 to designated this controller as Zone 4.  Phone lines go either way.  Two wires for the remote sensor (marked) and 2 wires for “Furnace” or however labels.  DC power for both House and Chassis (redundant) off at battery disconnect switches.  Install.  Repower. Do the CC2 reset (Google or read instructions provided with new Thermostat) so that the CC2 knows there are 4 zones now, like the old 5 button did.

It is also requested that this topic have no further posts until the above has been accomplished as the solution is known and simple.  Please report back afterwards.

Thanks

[Pduggs]

Thank you!

[Pduggs]

I’d like to thank Frank and Tom for their help in solving this problem and apologize for being difficult. This problem was new to me and my only weakness in maintaining my coach is a lack of understanding electrical issues. 
 

As they stated above, the new circuit board from Amazon (Dometic part#3312020) did the trick. Making sure to match up the two blue wires is obviously important, as both gentlemen advised.  I merely removed the old circuit board and connected the two blue wires on the new board with the matching existing red and white wires on the connector, connected the two phone lines and the blue temperature sensor.  Heat is now working in my bathroom as it did prior to the installation of the new ACs and thermostat.

This was a very simple job which I made more difficult than it was.
New board on left in pic and old on right. 

[Frank McElroy]

26 minutes ago, Pduggs said:

I’d like to thank Frank and Tom for their help in solving this problem and apologize for being difficult. This problem was new to me and my only weakness in maintaining my coach is a lack of understanding electrical issues. 
 

As they stated above, the new circuit board from Amazon (Dometic part#3312020) did the trick. Making sure to match up the two blue wires is obviously important, as both gentlemen advised.  I merely removed the old circuit board and connected the two blue wires on the new board with the matching existing red and white wires on the connector, connected the two phone lines and the blue temperature sensor.  Heat is now working in my bathroom as it did prior to the installation of the new ACs and thermostat.

This was a very simple job which I made more difficult than it was.
New board on left in pic and old on right. 

Thanks for the update.  I'll add it to the next parts list revision.

[Tom Cherry]

9 minutes ago, Frank McElroy said:

Thanks for the update.  I'll add it to the next parts list revision.

Double thanks for the update.  Frank gets two credits.  First for his continuing education of me, and others so that we can understand and help folks and not always burden him with that task.

Second is for doing the research on the Dometic site so that I could be of assistance and keep the fix “going”.

We do understand your concerns about “being smarter” than the tech that didn’t fully understand that if the old 5 button system had a Zone 4, then he needed to complete the job by replacing that control module as well.  Glad you were able to do it yourself.  You now have more knowledge and confidence.

Two things …

First, I assumed that the new CC2 thermostat had to be rebooted or reset.  Was that necessary or did you do that.  Knowing that will help when we start troubleshooting the new system.

Second, the most common failure or “my HVAC don’t work or is acting funny” is a communication issue in the dual inline female to female connections.  I have cleaned mine and probably should replace with the new spares I carry.  I would suggest that you order some on Amazon and have isopropyl alcohol (rubbing) and a few Q-tips in your “emergency” stuff kit.  Cleaning the male phone plugs will help,  BUT occasionally, there will be a failure in the phone lines and folk buy a kit and put on a new male end.  

Great job…enjoy….

 

[Pduggs]

2 hours ago, Tom Cherry said:

Double thanks for the update.  Frank gets two credits.  First for his continuing education of me, and others so that we can understand and help folks and not always burden him with that task.

Second is for doing the research on the Dometic site so that I could be of assistance and keep the fix “going”.

We do understand your concerns about “being smarter” than the tech that didn’t fully understand that if the old 5 button system had a Zone 4, then he needed to complete the job by replacing that control module as well.  Glad you were able to do it yourself.  You now have more knowledge and confidence.

Two things …

First, I assumed that the new CC2 thermostat had to be rebooted or reset.  Was that necessary or did you do that.  Knowing that will help when we start troubleshooting the new system.

Second, the most common failure or “my HVAC don’t work or is acting funny” is a communication issue in the dual inline female to female connections.  I have cleaned mine and probably should replace with the new spares I carry.  I would suggest that you order some on Amazon and have isopropyl alcohol (rubbing) and a few Q-tips in your “emergency” stuff kit.  Cleaning the male phone plugs will help,  BUT occasionally, there will be a failure in the phone lines and folk buy a kit and put on a new male end.  

Great job…enjoy….

 

I did reset the stat after I installed the new board. Zone 4 didn’t show up on the stat before, but after the reset it was there. 
 

Thanks for the tip on the phone plugs. 

[96 EVO]

Makes you wonder why companies like Dometic can't just make their new units 'Backwards compatible'!

Seem's they just want to get deeper into your wallet!