In search of an old thermostat

[trtlchk]

Hi All!


I have a 2011 Thor Majestic 19G. It was originally made for Cruise America, and I am the 3rd owner. It came with no manuals at all.


Our thermostat died. It is no longer manufactured. Current generation thermostats do not work with my air conditioner. So, the nice lady on the phone for Thor's customer service said my only option is to buy a new generation thermostat ($120) AND replace the rooftop A/C (which works fine- ~$700) because new A/C units have the new style control board that will talk to the new thermostat.


So, before we go through all that, I figured I'd see if any of you fine folks happen to have an old thermostat laying around that might work for me. (See attached pictures). I've tried ebay, and every other place I can think of.



Or, if anyone has any other ideas I'm open to suggestions!



Thanks!!!

[abjbrtd]

Greetings and Welcome

Google your ac manufacture/model #.
Should be pretty easy and cheap to find a compatible thermostat.

I bet she suggested taking it to an "authorized" thor dealer.

[trtlchk]

Apologies- I was actually talking to the Dometic Customer Service rep, not Thor. Thor was no help- they just told me to go to a local dealer.


The lady at Dometic took my A/C part number (641715.301CO) and then had to put me on hold because it's apparently an obscure unit that she had never seen before.



She did some research and then came back with the answer that that air conditioner model was made to some specific UL code requirements, or something like that, and it would only function with the thermostat that was installed. But, that thermostat was discontinued after the sub-contractor that made it (Inventsys) was sold.



Just to see, though, I bought a new style thermostat on Amazon (with free returns) and we tried it. Customer service was right, it didn't work. I really had hoped she would be wrong.

[16ACE27]

Any battery powered thermostat should work; something like this:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The thermostat basically has 2 functions in regard to your AC:

1 - Turn the compressor on and off
2 - Turn the fan on and off

It normally does this by completing the circuit to the fan and compressors relays by either connecting a wire to ground or by supplying 12 VDC to the relay circuit.

I have been replacing analog thermostats in RVs since 2004 with standard battery powered digital house thermostats. it is not rocket science despite what Thor may lead you to believe.

There are also plenty of YouTube videos that will instruct you on how to do this.

EDIT:

Dometic may be right. It appears this unit uses a proprietary control system with an RJ11 (telephone jack) thermostat connection. You can download the manual here:

https://data2.manualslib.com/pdf7/15...e2&take=binary

[trtlchk]

I replaced the thermostat in our last RV, but that thermostat only controlled the furnace. This one controls the A/C and the furnace. The wires coming out of the wall look like a phone cord, plug and all- not the normal wiring you usually see for a thermostat.



Dometic said that the furnace is wired into the air conditioner's control board, and that the thermostat plugs into that control board using the "phone Style" cable, and that's how it runs both. I'm afraid I don't quite understand how we could possibly wire up a traditional thermostat.


EDIT- Sorry, I just saw your edit.

[powerboatr]

Originally Posted by 16ACE27

Any battery powered thermostat should work; something like this:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The thermostat basically has 2 functions in regard to your AC:

1 - Turn the compressor on and off
2 - Turn the fan on and off

It normally does this by completing the circuit to the fan and compressors relays by either connecting a wire to ground or by supplying 12 VDC to the relay circuit.

I have been replacing analog thermostats in RVs since 2004 with standard battery powered digital house thermostats. it is not rocket science despite what Thor may lead you to believe.

There are also plenty of YouTube videos that will instruct you on how to do this.

EDIT:

Dometic may be right. It appears this unit uses a proprietary control system with an RJ11 (telephone jack) thermostat connection. You can download the manual here:

https://data2.manualslib.com/pdf7/15...e2&take=binary

we used a plain old house thermostat a few years ago for our fivers a/c unit. you just need to know how many wires you need, as in is yours a heat pump or just a/c? might be worth a look. take your old one to lowes or home depot or similiar

[abjbrtd]

Don't be afraid of the rj11

Here are some parts that make it possible to work around the rj11.
I linked Walmart, you can get these from amazon, ebay etc.

https://www.walmart.com/ip/Unique-Ba...aptor/47551182

https://www.walmart.com/ip/6P4C-RJ11...White/47593244

PLEASE NOTE when purchasing rj11 products ALWAYS make sure there are 4 conductors, spade tips, etc.

Plug your rj11 sticking out of the wall into the coupler then the rj11 from the spade-lug into the coupler then carefully stick the coupler in the wall, being carefull not to drop the spade tips oppss.
Now your ready to attach to your "new" thermostat when you find one.

[16ACE27]

Originally Posted by abjbrtd

Don't be afraid of the rj11

Here are some parts that make it possible to work around the rj11.
I linked Walmart, you can get these from amazon, ebay etc.

https://www.walmart.com/ip/Unique-Ba...aptor/47551182

https://www.walmart.com/ip/6P4C-RJ11...White/47593244

PLEASE NOTE when purchasing rj11 products ALWAYS make sure there are 4 conductors, spade tips, etc.

Plug your rj11 sticking out of the wall into the coupler then the rj11 from the spade-lug into the coupler then carefully stick the coupler in the wall, being carefull not to drop the spade tips oppss.
Now your ready to attach to your "new" thermostat when you find one.

You're right; he doesn't have to be afraid of the RJ11 - he has to be afraid of the proprietary control board on the other end with no documentation as to what the 4 wires do on the RJ11 jack.

[ducksface]

Yes, and due to that remote circuitry in the ac housing we don't know the thermostat is indeed bad. It could be the board in the ac housing just as easily.

Buy a new ac and get rid of that entire thing.
It's just an added rv cost. It happens to all of us.

My digital thermostat was 38 bucks on amazon.
A roof ac is cheap.
Fishing the new wires might suck.

I know they make Bluetooth thermostats, do they make a wireless ac to thermostat connection?

[Hugh.vines@att.net]

Take your rv and print to a vocational school that has a hvac department and they will fix it for free

[trtlchk]

Thanks Everyone!



My hubby is going to look over the wiring diagrams and try to install a thermostat from Lowes. The way we figure, there's a chance we'll get the wiring right and it will work, and if we get it wrong and fry the whole thing, we're no worse off than before.


If we do end up replacing the unit, I'm inclined to try to install an older style A/C without a thermostat- the ones that have the controls directly on the unit itself. Our last camper (a 2014 pop-up) had one of those, and I'm hoping they're still manufactured.


Then, our issue will be getting the furnace hooked up to a thermostat, but this should be easy. If we do this, we'll likely re-locate the thermostat, since the furnace blows right on it and it tends to short cycle which drives me crazy and causes the "kitchen" to be warm while the "bedroom" is freezing. If you're not familiar with the layout of this rig, it's cozy, shall we say?

[abjbrtd]

Originally Posted by trtlchk

Thanks Everyone!



My hubby is going to look over the wiring diagrams and try to install a thermostat from Lowes. The way we figure, there's a chance we'll get the wiring right and it will work, and if we get it wrong and fry the whole thing, we're no worse off than before.


If we do end up replacing the unit, I'm inclined to try to install an older style A/C without a thermostat- the ones that have the controls directly on the unit itself. Our last camper (a 2014 pop-up) had one of those, and I'm hoping they're still manufactured.


Then, our issue will be getting the furnace hooked up to a thermostat, but this should be easy. If we do this, we'll likely re-locate the thermostat, since the furnace blows right on it and it tends to short cycle which drives me crazy and causes the "kitchen" to be warm while the "bedroom" is freezing. If you're not familiar with the layout of this rig, it's cozy, shall we say?

We have 1 of these, black from Amazon. It works really well.
DW 3840RBK Heat Vent
here's a beige one from Ebay.
https://www.ebay.com/itm/5-1-2-Face-...edirect=mobile

[ducksface]

I have the same duct valves as above.
Installs in moments and puts air where you want it.
We only needed two of them to change the entire rv to a mostly consistent temperature.