thermostat

[carl7946]

my Coleman thermostat is working backwards on ac anybody got a clue

[rick danger]

if you turn it up in heat mode the heat will come on....if you turn it up in a-c mode the a-c will go off.....is that what you mean?

[3'senough]

Please elaborate...AC is Heat and vice versa or your setting the temp higher to get it cooler? Wires not connected correctly is my first guess. Warranty?

[carl7946]

If I turn thermostat up towards 90 ac comes on and down toward 60 ac goes off

[mike837go]

Originally Posted by carl7946

If I turn thermostat up towards 90 ac comes on and down toward 60 ac goes off

Normal operation.

You want the A/C to run when the air is too hot and stop when things are cool enough.

And the heat works the exactly opposite.

[12VOLTMAN]

Sounds like it is wired backwards. Has it ever worked properly?

[rryman]

Sounds like the heat wire and AC wire are reversed. How does it act on heating?

[3'senough]

Originally Posted by carl7946

If I turn thermostat up towards 90 ac comes on and down toward 60 ac goes off

This is normal operation. If you set the temp to 5 degrees above the ambient temp in the room (reading on the unit) what happens? If it comes on then you are fine.

[troutslayer]

Originally Posted by mike837go

Normal operation.

You want the A/C to run when the air is too hot and stop when things are cool enough.

And the heat works the exactly opposite.

I don't think that is right. If it's 90 in the RV, you want to move the thermostat to 60 ( or something lower than 90) so that when the inside of the RV cools down to 60, it shuts off. If I understand...you are saying that the AC doesn't run when you turn the thermostat down, and that's not the way it should be.
Sounds like you have some wires crossed. Either that or I am completely confused...not the first time.

[12VOLTMAN]

Troutslayer is correct.

[mike837go]

Originally Posted by 12VOLTMAN

Troutslayer is correct.

Now that I re-read the posting (correctly) I have to agree with Troutslayer. My bad.

The thermostat is wired incorrectly. The A/C unit is wired to the heater's contacts. And I expect the heater is wired to the A/C's contacts.

If this was my trailer, I'd have the cover off the thermostat and be figuring out which wires go to the furnace and A/C and which contacts close/open on temp rise. Then set everything up correctly. Test. Then try again on the rewiring. (It usually takes me a try or three to get it right).

But it sounds more like a dealer/warrantee repair.

[RedHorse1]

If it's a Furnace and A/C Thermostat I'll bet the A/C is wired to the Furnace side of the Thermo and visa-versa.

[rryman]

Sounds like "W" and "Y" terminal connections are reversed, w being heating and y being cooling leg. At least that's the way it is on most residential stats.

[mike837go]

I know another thread mentioned replacing the factory mechanical thermostat with a residential fully electronic one. That will definitely change things!


Maybe even for the better.

[carl7946]

No heat works correctly

[rryman]

I just changed out our Coleman/Mach mechanical with the digital replacement and it changed out wire-for-wire and works fine. I did notice that they don't seem to use the same color coding as they do in residential systems. I don't know that there are any hard and fast rules about color coding though.

[mike837go]

Originally Posted by rryman

...snip... I don't know that there are any hard and fast rules about color coding though.

RV's definitely do NOT have any standards whatsoever!

The lighting may use the 4 wire (brown running lights, yellow left, green right (or is the other way around?)) Generally, white is ground or neutral or negative. Black or red will be 110/220 hot. Unless it's 12V positive. Green or green with a yellow trace should be 110/220 building ground.

Then they don't bother with special colors for the furnace, A/C or other system control wires.

Any repairs ignore color coding as well.

[rryman]

………….RV's definitely do NOT have any standards whatsoever!
====Yep, that always adds another dimension to the trouble shooting!! Actualy saw a power utility once using "Green" for a phase conductor on a 3-phase system!

[3'senough]

Originally Posted by 3'senough

This is normal operation. If you set the temp to 5 degrees above the ambient temp in the room (reading on the unit) what happens? If it comes on then you are fine.

I was wrong and thinking heat!!! AC temp setting down below temp in coach = on. Sorry for the mix up.

I would ask the dealer how it is supposed ot be wired and check yours first to save you a trip.

[nylyon]

So, heat works correctly (move temperature selector towards a higher temperature, furnace comes on, moving to a lower temperature goes off). BUT the A/C works the same way, moving the temperature selector to a higher temperature it comes ON, and lower it goes off.

My vote is defective thermostat. The A/C is pretty simple, either it's on or it's off. The Thermostat is going to determine if it's on or off. It has to be wired correctly if A/C is working at all with the AC/Heat selector in the AC position and the temperature selector at 90. If it was wired incorrectly the A/C would not work in with the selector in A/C mode.

So... (in my simplistic mind) the Thermostat is bad.

I would replace with a digital model (I went with Coleman Digital, but others use use a residential model with some minor mods).