[cfree3]

Is there any way to get both compressors running all the way down to the thermostat set point rather that having one compressor running for the last two degrees

[Richard]

Not with the original SCS thermostat. However, the Coleman replacement for a two stage AC acts just like that. Both stages stay on until the set point is reached.

https://www.amazon.com/Coleman-6536A3351...ast_sto_dp

[cfree3]

Not with the original SCS thermostat. However, the Coleman replacement for a two stage AC acts just like that. Both stages stay on until the set point is reached.

https://www.amazon.com/Coleman-6536A3351...ast_sto_dp

Do you have a wiring diagram on how to match up the old wires from SCS thermostat to the new coleman thermostat?
I found another tread with information and I think I have it wired right.  The SCS themostat had both compressor wired together however instead of seperate.  Maybe that was so both compressors would run until the setpoint.  Not sure.  So I wired them the same way to the new Coleman Thermostat. 

The reason we had to replace the thermostat was that we had a power surge from the generator which fried the thermostat and the relay on the AC board for the thermostat.  We had that relay fixed on the board and the rest of the board checked out ok.  The fuse had blown for the thermostat and when I replaced that the new thermostat lit up.  It would turn on the Aquahot and the AC fan if set to on but set on auto the compressors are not kicking on still.  I noticed that the fuse for the thermostat is wired to a black relay on the panel where the fuses are.  Please see attached picture.  Do you think this relay could be blow also.  If so, does anyone have a replacement part number for it?
   

[Richard]

First, the compressors are NOT supposed to be tied together at the thermostat. Y1 to yellow, Y2 to orange.

There will be Fan Hi and Fan Lo wires.

There are two(black?) wires on the new compressor that are for freeze protection on newer AC units. They must be tied together for the Tstat to work properly.

If you have 12V at the tstat then your problem is somewhere else.

That relay that you have in the picture, is that in the passenger kick well panel, or below the 120V breaker box in the rear closet?

I’ll send you a wiring diagram tomorrow. In the mean time can you post a picture of the wires you have at the TSTAT.

[Richard]

Ok, I am going to try to help, but it is going to take some hands on work on your end.

I could take my thermostat off the wall and tell you what color goes to what, but that may not be the same wiring you have, so let’s go about this in a better way.

When you look at the wires on the Newell side, you will find one bundle of light gauge wiring sheathed in a common cable. It may have six to eight colored wires in it. You will find three wires coming to the tstat that are larger in diameter

RED/yellow stripe 12V positive
Light green. Ground
yellow/red stripe. Aqua hot

Brown. GL lo Fan
Green. GH. Hi fan
Yellow. C1 Compressor 1
Orange C2 Compressor 2

Some tstats use Blue for 12V pos, so connect the red/y to blue
Connect the tstat heat white to the Aquahot yellow/r

The tricky part to the new tstat is that the two GREY wires associated with freeze protection have to be connected together OR the compressors will not come on.

I am confused by your statement that a relay on the AC board that powers the tstat was replaced. I am not aware of a relay on the board that provides power to the tstat.

Waiting on your answer about the location of the relay in the picture.

By the way, did you get your transfer switch issue figured out?

[cfree3]

First, the compressors are NOT supposed to be tied together at the thermostat. Y1 to yellow, Y2 to orange.

There will be Fan Hi and Fan Lo wires.

There are two(black?) wires on the new compressor that are for freeze protection on newer AC units. They must be tied together for the Tstat to work properly.

If you have 12V at the tstat then your problem is somewhere else.

That relay that you have in the picture, is that in the passenger kick well panel, or below the 120V breaker box in the rear closet?

I’ll send you a wiring diagram tomorrow. In the mean time can you post a picture of the wires you have at the TSTAT.

Great!! I will tie the freeze protection wires together and separate the compressors to see if that gets the system to work. Thanks so much!!

The relay was on the panel below the 120 breakers in the back.

Thanks

[Richard]

   

[Richard]

That relay in the rear closet is connected to the Master ON/OFF switch for the 12V lights in the coach. My master switch is by the entry door. If you have 12V lights in the coach, that relay is working.

[Richard]

Just a heads up, I edited the post where I listed wire colors. I took mine apart today to confirm. I did not want to lead someone astray when referencing this post in the future.