HEAT / COOLING THERMOSTAT CIRCUIT DEAD

[Gary Magin]

I had previously requested help under " FURNACE CIRCUIT WILL NOT RUN " because the furnace circuit wouldn't run.  The A/C's did work.  All voltages are up and proper, coach is plugged into 50A.

I just completed the recommendations of checking and cleaning with alcohol all the phone line type connectors at all 3 A/C's,    I also did the thermostat connector.

I did one connector at a time and am sure there was no wire mix-up.  The system seems dead now, the thermostat will not reset to FF it will not lite up at all.

I have rechecked all connections at least 4 times, and have tried new female connectors, no results!   I haven't opened the top cover of the A/C's yet.

Could something have shorted out while brushing the connectors?  Is there a fuse for the system somewhere?  I did find the hidden Duo-therm panel ( 3109226.005 ), the fuse in it is good.

Any and all suggestions greatly appreciated

Thank you in advance

Gary Magin

2009 Dynasty Yorkshire

[Tom Cherry]

29 minutes ago, Gary Magin said:

I had previously requested help under " FURNACE CIRCUIT WILL NOT RUN " because the furnace circuit wouldn't run.  The A/C's did work.  All voltages are up and proper, coach is plugged into 50A.

I just completed the recommendations of checking and cleaning with alcohol all the phone line type connectors at all 3 A/C's,    I also did the thermostat connector.

I did one connector at a time and am sure there was no wire mix-up.  The system seems dead now, the thermostat will not reset to FF it will not lite up at all.

I have rechecked all connections at least 4 times, and have tried new female connectors, no results!   I haven't opened the top cover of the A/C's yet.

Could something have shorted out while brushing the connectors?  Is there a fuse for the system somewhere?  I did find the hidden Duo-therm panel ( 3109226.005 ), the fuse in it is good.

Any and all suggestions greatly appreciated

Thank you in advance

Gary Magin

2009 Dynasty Yorkshire

OK….fundamentals that way you understand.  The “12 VDC” power comes from a fuse in the main panel.  May be marked…or NOT.  Mine is the SATELLITE fuse.  There is ONE a continuous 12 VDC line that runs to the control module in each AC unit.  You may (probably) have a HIDDEN HVAC Module behind some panel.  That is a “fourth” zone.  It controls the bathroom heater.  Not positive, but that was the way it was done in some prior years on the Dynasty snd above.  You will need to look at the HVAC a print to see if you have a separate AquaHot zone,  but there is DC to all of the modules.  If you had internal lights  then there is power to the fuse panel.  Some people have turned off, mistakenly, their salesman switch and think that 

The modules are accessible from the roof top.  They have DIP as switches on them.  Each one is specifically coded, via the DIP’s for that zone,  

NOW…you probably have TWO thermostats.  Therefore each thermostat has to have power,  the Thermostat gets a Multiplexed low voltage source.  The Control module has 2 RJ11 cables (phone male ends).  These cables are UNIVERSAL or BiDirectional…..as in it don’t matter which one gets the two other cables.  They will work if you swap them….otherwise,,,,an issue.

NOW when you said  the AC’ worked…..do you mean each system (front and rear).  AC’s can work….but there can be communication issues with the control modules,  I assume, but have to ask.  Anytime you disconnect your system, or move or disturb a connection, you MUST do the reset.

The fact that you have lost it all says that there is PROBABLY a connection issue.  
 

NOW…there is a thermostat or remote sensor for every zone and there is a control lead (think a light switch’ that signals the AquaHot to run.  Have you looked at the AH control panel.  Did you turn ON (usually the diesel?).  There is a shutdown for low boiler fluid as well as a low battery cut off.  There is a reset button and you use a paper clip to reset the AH if there are red lights.  You need to read the owners manual for how it should look….as well as the AH.

My advice…..do the reset.  Check the fuses….but if ALL AC’s work or you can run the fan…you have 12 VDC to each unit.  I also recommend replacing the dual inline RJ11 connector….some folks have had to reterminate the male ends.  Any least little disruption, due to the low voltage will upset the “brain” in a thermostat.  The only way to fix that…..fix the connection….then reset each Thermostat.

That’s it….work on it and report back…

[Chuck B 2004 Windsor]

When all the microprocess control devices break down, I try to replace them with a mechanical device.  Then in the future you do not have deal with the so called "brain"

issues. 

Chuck B 2004 Windsor 

[Tom Cherry]

3 hours ago, Chuck B 2004 Windsor said:

When all the microprocess control devices break down, I try to replace them with a mechanical device.  Then in the future you do not have deal with the so called "brain"

issues. 

Chuck B 2004 Windsor 

Yes, an alternate.  But the system is NOT a convenient furnace.  He has a 4 zone AquHot.  Each of the zones there have to be integrated with the system.  So, he would have to run 4 control lines…and sort of gut his AquaHot.  Then run the lines to the zones.  Yes….in theory, maybe wireless….with solenoids or relays.

This issue is has not been totally defined….as in….does the AH have any “shutdown” issues….if it is inoperable, then, of course the thermostats will not bring on heat.

Need to trouble shoot and focus on the issue or component…..then fix.  Last resort would be abandon the thermostat loop that has been working for years..

[Gary Magin]

UPDATE

I found and replaced the 2amp fuse for the A/C control circuit and now the thermostat ( I only have 1 ) lites up and I did the reset to FF.

I think the phone line communication is working, when I switch zone 4 to furnace, I hear a click in the hidden Z4 control module they hid in the wall behind the thermostat. At least I think the com is working from the thermostat up to A/C1 then to A/C2 then to the hidden board.  I did only find two com cables and one connector in A/C 3 which is the end of the com circuit  ( my schematic shows the com circuit as  --thermostat to ACzone1 to ACzone2 to Zone4controller to ACzone3-- )

The zone 4 doesn't actually run though!  I think this leads me to the aquahot 600 control board???

There are no faults shown on the board ( I pressed the reset button anyway )  The 30a fuse is intact and there is power to the board.

The aquahot heats on electric ( I have not tried the diesel because it would smoke me out of the shop )

The aquahot engine preheat works and runs the circ pump.

Eagerly await any suggestions on testing the aquahot for these conditions

Thank You

Gary Magin

2009 Dynasty

[Gary Magin]

UPDATE  /  SUCCESS

After all the testing previously discussed, my focus turned to the Aquahot control board.  This board is exposed and mounted on a bay panel on the pass side of the coach and shares the same bay as the liquid tanks and their access over on the dvr side.  That bay is almost always humid, from flushing etc. 

On very close examination of the components on the board I noticed some minute(sp) green crusty corrosion on a few of the component connections. 

$500 later for a new board and the heating system is up and running. 

My question to any electrical folks out there  --  The solder side of the new board does seem to have some type of conformal coating on it.  Is it possible and permissible to apply either a silicone or a polyurethane conformal coating to the component side of the board???

The original did last 14 years, and I doubt I will be MH'ing in another 14 years, but just want to avoid another $500 ( or more )

Thank You all for the prior help.

 

Gary Magin

'09 Dynasty

[Tom Cherry]

46 minutes ago, Gary Magin said:

UPDATE  /  SUCCESS

After all the testing previously discussed, my focus turned to the Aquahot control board.  This board is exposed and mounted on a bay panel on the pass side of the coach and shares the same bay as the liquid tanks and their access over on the dvr side.  That bay is almost always humid, from flushing etc. 

On very close examination of the components on the board I noticed some minute(sp) green crusty corrosion on a few of the component connections. 

$500 later for a new board and the heating system is up and running. 

My question to any electrical folks out there  --  The solder side of the new board does seem to have some type of conformal coating on it.  Is it possible and permissible to apply either a silicone or a polyurethane conformal coating to the component side of the board???

The original did last 14 years, and I doubt I will be MH'ing in another 14 years, but just want to avoid another $500 ( or more )

Thank You all for the prior help.

 

Gary Magin

'09 Dynasty

Great.  Never let silicone within the same zip code as electric contacts.  I sprayed a steering column ignition key switch once.  It took many cans of contact cleaner and WD40 so I could start it.

I’ll throw this out….battery terminal spray may be a solution……but research and understanding is required….

Bulb grease is an option…..see what our “techs” say….

[96 EVO]

On 12/29/2022 at 12:13 PM, Chuck B 2004 Windsor said:

When all the microprocess control devices break down, I try to replace them with a mechanical device.  Then in the future you do not have deal with the so called "brain"

issues. 

Chuck B 2004 Windsor 

Yeah, that worked well in 1972 😁!