New and distressed

[Franklin]

Hi im new i have a 1978 corsair 20ft ot has a coleman mach 1 rooftop unit i was wanting to put it on a thermostat help pls T.I.A

Sent from my SM-N910P using Fiberglass RV mobile app

[SherryNPaul]

congrats on your new trailer.
Does the ac work?
Sherry

[Darral T.]

Call Coleman. They make digital thermostats for their A/C's now.

Originally Posted by Franklin

Hi im new i have a 1978 corsair 20ft ot has a coleman mach 1 rooftop unit i was wanting to put it on a thermostat help pls T.I.A

Sent from my SM-N910P using Fiberglass RV mobile app

[Franklin]

Thank you for the response yes the a/c does work im currently trying a honeywell digi thermostat and while it works great with the furnace i had read one of the forums on here where a guy wired up a digital thermostat to not only control the compressor but the fan as well instead of it constantly running so i had to use a 120 vac to 24 vac spdt relay but nothing is working ive disconnected the furnace but still nothing and with it being 4th of july weekend nothing is open any advice would be nice

Sent from my SM-N910P using Fiberglass RV mobile app

[Franklin]

I checked power at both ends of the relay and got it but nothing is engaging

Sent from my SM-N910P using Fiberglass RV mobile app

[Darral T.]

I installed a Digi thermostat because of the LONG time between cycles and the humidity that would rise in my Scamp between those cycles. A gentleman on the Casita forums came up with the idea you see here in my photos. I took it a step further and added a small fan to my thermostat because in the Scamp, the area where they install their furnace therm is in a dead-air area. So the cycling with a remote thermostat was as bad or WORSE than the one one on the A/C itself- including the heat strip I had installed.

SO, look over my drawing as it shows in GREAT detail- the wiring. I take NO responsibility should you use it and it doesnt work for you. But maybe it can help you trace your connections and see if you can find a fault that way. I list the # of my relay and it's worked flawlessly for nearly 6 yrs now. I can keep my temps within ONE degree if I desire.

The only other mod I had to make to it was because of the Coleman's onboard thermostat. It would kick off the compressor BEFORE my thermostat would shut the unit down. I wound up adding ANOTHER relay inside the A/C unit and "jumpering" the compressor wires. So, if my thermostat is in control (I added a bypass switch as well for the thermostat/relay unit- GREAT addition btw) then the compressor will run until my Hunter shuts the unit down. I've ran my temps as low as 65 deg at night in my Scamp for sleeping. Not one issue. It doesnt run long enough to ever freeze up and Coleman put their blessing on it believe it or not!

Here's the link!
https://www.flickr.com/photos/503516...57626806751813

[cmartin748]

On the thermostat:
Rh and W go to the furnace (remove the tab between r and rc if there is one)
RC or R goes to the 24 volt hot side of your transformer.
Y goes to one side of the 24 volt coil on your relay.
The other side of your transformer (C) goes to goes to the other side of your relay (C)
Find the wire to your AC and remove it from the breaker.Connect a wire from the breaker to one side of the normally "open" pole on your relay and the wire you removed from the breaker to the other side of the normally "open" pole.
continued.....

[cmartin748]

Set the fan to the speed that you want on the AC and the Thermostat on the AC to its highest setting.
If nothing was "cooked" earlier it should work fine.

Make sure all low and high voltage wiring is separated.bahd enclosed.
I accept no responsibility for this information
Good luck
Charlie

[Darral T.]

Sorry Martin. I believe their Coleman is like mine, there IS no "transformer"! You're thinking house units. I (we) use onboard 12v to power the thermo/relay in my diagram. My diagram clearly defines all of this. The "24v transformer" info will get them confused- again- if their unit is like mine.

[cmartin748]

the transformer and relay are "field supplied"
This method has nothing to do with the unit itself and takes over the power before it is supplied to the unit.

[Franklin]

Now im confused which method do i try????

Sent from my SM-N910P using Fiberglass RV mobile app

[cmartin748]

Either will work fine. Your choice. I did my Scamp this way 4 years ago and 7 others since. Pick one lol

[Darral T.]

I guess as he says, take your choice. I offer a drawing and no transformer is necessary. I ordered my parts- the Omron relay from Mouser Electronics. If you're going to run a furnace on the thermostat as well, you'll need another wiring setup. I dont have nor want the furnace. My Coleman DOES have the heat unit and the same thermostat works fine except you switch from "Cool" to "Heat" mode....of course you have to switch it over on the overhead unit as well. Mine is designed only to simply cut the entire unit on/off.

For what it's worth, Coleman does offer the digital thermostat with their units now that controls the fan separately, etc. which is ultimately the best setup. I'm sure many RV manufacturers are prewiring now to work furnaces, roof units, etc. all in one.

Good luck with your decision.