Dometic T-Stat has no power

[sourdough]

Originally Posted by chuckster57

Yup! Now that I’m in a collision repair shop, it’s scary how many specialized tools I’ve bought in the last year

And I am looking at “real” retirement in October/November this year.

October/November? Ah, come on Chuck, you know you're having a ton of fun! And all those tools? You want a job so you can use them! Working for someone, report to work...go home when "the work's done" - think about all that you would miss! On the other hand, "come on in, the water's fine"!! Put that calendar on the wall and start counting down...and plan a trip to celebrate!

[hankaye]

Howdy All;

Everyone keeps mentioning testing for 12dcv. Has anyone suggested that OP unplug the trailer from the external electric source and THEN checking to see if the batteries are working properly? Mine is a 2008, single A/C and just had my heater cleaned out (Mud daubers), Took the thermostat by surprise I guess, still wouldn't run consistently, so I went and serviced the batteries as it was on the schedule. Presto chango, it works as it should now. Batteries were a bit thirstier then the last time.
Just a thought. So, I'm passing it along as I noticed that OP's rv is a tad older then mine.

hank

[ChuckS]

Originally Posted by hankaye

Howdy All;

Everyone keeps mentioning testing for 12dcv. Has anyone suggested that OP unplug the trailer from the external electric source and THEN checking to see if the batteries are working properly? Mine is a 2008, single A/C and just had my heater cleaned out (Mud daubers), Took the thermostat by surprise I guess, still wouldn't run consistently, so I went and serviced the batteries as it was on the schedule. Presto chango, it works as it should now. Batteries were a bit thirstier then the last time.
Just a thought. So, I'm passing it along as I noticed that OP's rv is a tad older then mine.

hank

The Roof A/C control boxes and gateways will get their DC power sent to them from the power center panel from one of the fused DC circuits. So whether the 12 volt source is battery or converter makes no difference.

The main point is: those roof top A/C control boxes ALWAYS have 12 volts to them .. either from the batteries or the converter.

On an In Command controlled HVAC system then often times one of the gateways "hangs a relay up" and removing both battery and shore power for a few minutes will often restore HVAC control via In Command..

I have not seen a CCC2 thermostat problem ( Not turning on ) be caused by a gateway relay.. The thermostat will turn on IF there is 12 volts coming to it from the splice feed source up on the roof down thru the 4 wire telephone cable

** Edited - your 2008 Cougar OEM thermostat was the older analog style unit and it does not use CANBUS control like the CCC2 multizone digital thermostat does..

[MontanaChef]

Originally Posted by ChuckS

I’ve added an image from a pdf I wrote on thermostats and this pic shows you the Zone 1 roof AC control box and gateway ( black smaller box)

You will see two sets of wires with twist caps.. this is the incoming 12 vdc from the power center panel up to that roof control box and gateway

Look for connections like this and then measure for 12 volts.. if you have 12 volts at those two twist cap connections then you KNOW you issue with the dead thermostat is in the four wire telephone cable from the roof to the thermostat

No power at the control box. Any suggestions? Pics of where I tested.

[MontanaChef]

Originally Posted by ChuckS

I’ve added an image from a pdf I wrote on thermostats and this pic shows you the Zone 1 roof AC control box and gateway ( black smaller box)

You will see two sets of wires with twist caps.. this is the incoming 12 vdc from the power center panel up to that roof control box and gateway

Look for connections like this and then measure for 12 volts.. if you have 12 volts at those two twist cap connections then you KNOW you issue with the dead thermostat is in the four wire telephone cable from the roof to the thermostat

Also not seeing a black gateway box at Zone 1

[chuckster57]

Gateway box is for HVAC that is controlled by InCommand. You don’t have it.

[chuckster57]

Did you remove the bell connectors to test?

I take it already used a meter to verify voltage at every 12V fuse?

[MontanaChef]

Originally Posted by chuckster57

Did you remove the bell connectors to test?

I take it already used a meter to verify voltage at every 12V fuse?

Have not metered the fuses yet. I will do now. Thank you.

[MontanaChef]

So you guys won’t believe this or may be you will. The problem all along was a bad battery. And now apparently a bad converter switch. After all the testing I was doing, control box, com cable and fuses I decided to put my meter on our battery. Sure enough it read .68. Even though (which I’m trying to understand) my panel says 13.2 VDC that makes no difference. As soon as I put my battery charger on and plugged in my t-stat everything works. Except now my converter switch. I found out my converter switch was bad cause I decided to try starting my generator and it wouldn’t convert over like it normally does when we boondock or have a power outage. Anyway, I want to thank all of you for helping me out in my time of need. From 1 American Patriot to others….THANK YOU and God Bless!

[chuckster57]

Was it the transfer switch? Your converter doesn’t have a switch. When you saw 13.2 volts on the panel that’s the converter output.

What was switched off? I’m confused, because it sounds like you may have a different issue.

[MontanaChef]

No it’s the transfer switch. We had one go out before but had it replaced within a day so nothing went out. When I started the generator the VDC usually always jumps up to 14.4 and then things kick on. This time like last time it didn’t. I understand now that even though we are connected to shore power (50amp) if the battery is bad and not being charged we lose the other things. If I have other things going on I don’t know. Right now -the converter switch everything is working like it should.

[chuckster57]

Well at least you have heat.

[MontanaChef]

I always thought that if I was on shore power that the battery would always have charge. We have had some really cold - temps lately and my guess is the cold zapped the battery. Again not sure. What I do know is that the transfer switch is bad. But right now how does that equate to a 13.2 VDC reading on my console screen. ?

[MontanaChef]

Originally Posted by chuckster57

Well at least you have heat.

Yes. Happy wife, happy life!

[chuckster57]

Originally Posted by MontanaChef

I always thought that if I was on shore power that the battery would always have charge. We have had some really cold - temps lately and my guess is the cold zapped the battery. Again not sure. What I do know is that the transfer switch is bad. But right now how does that equate to a 13.2 VDC reading on my console screen. ?

Because there may be another issue. The converter charges the battery and supplies 12V to the fuse panel. If the monitor panel said 13.2VDC then the converter is producing 13.2VDC.

The transfer switch simply changes the 120VAC source from shore to generator.

[hankaye]

MontanaChef, Howdy;

The converter charges the battery and supplies 12V to the fuse panel just as Chuck said. The bit with the battery is, it is what supplies the AMPS to run the heater, fan, burner the whole shebang. The converter does not supply that amount of AMPS. It supplies enough to give all sorts of friendly readings just not enough "oomph" to keep the furnace running. That's why we are encouraged to check and top them off on a regular basis.

hank