Coleman help

**hvacguy1075** · 09-19-2005, 08:40 PM

Having problems with a coleman split system in a mobile home it has 2 control wires to the thermostat and that is what it calls for. The airconditioning will not turn off. if you jump the to control wires together that go to the thermostat the airconditioner will turn off and i believe it is supposed to do this when the stat is closed. it has a honeywell t-87 with a heat and cool subbase on it with one wire hooked to rh and rc and the other wire to the w terminal.when the toggle switch is flipped to heat the furnace works just fine but when the toggle switch on the furnace is switched to cool the airconditioner will never turn off. OK is this the right thermostat for this application i know its a mercury bulb in a trailer buy will it work or do i need to sell customer a new stat. i cant figure out why it wont shut off. I need help can sombody with trailer hvac experience please help me . i havent worked on many trailers. please help and thank you

**Twilly** · 09-19-2005, 08:43 PM

Remove the sub-base. also the ac will only work in with the set in the heat mode, the customer must switch the setting at the control panel in the furnace to ac.

[Edited by twilli3967 on 09-19-2005 at 08:46 PM]

**trane** · 09-19-2005, 08:44 PM

no sub base is needed

**Christheheatingdude** · 09-19-2005, 08:45 PM

How is it wired at the furnace? Seems rather weird to me, like someone didnt want to fish a new wire to the stat when A/C was added.

**trane** · 09-19-2005, 08:46 PM

Originally posted by twilli3967
Remove the sub-base.

I got to learn how to type with both hands

**trane** · 09-19-2005, 08:48 PM

Some of these furnaces have the switches on the furnace for heat, cool, auto, and off.

**2hot2coolme** · 09-19-2005, 08:50 PM

Somethings really screwed up there.
Split system with only 2 control wires, how long ago was AC installed?
Sounds to me like the sub-base needs to be there, & you need to pull 2 more wires to the stat.

**smokin68** · 09-19-2005, 08:52 PM

Trailer or house it doesn't matter,it's still an A/C unit. Turn the toggle to cool,make it run non-stop, and trace the voltage till you find what controls it. It has a contactor somewhere to start at. Should be pretty easy to spot the guilty part.

**hvacguy1075** · 09-19-2005, 08:52 PM

Trane
it does have them controlles in the furnace that you mentioned. i type with one finger also .

**Christheheatingdude** · 09-19-2005, 08:52 PM

ok, hadn't seen that yet. But I was thinking intertherm, and not coleman.

**hvacguy1075** · 09-19-2005, 08:56 PM

if i remove the 2 wires from the stat and touch them together the ac turns of . it has a relay that the stat operates . i am pretty sure the problem is in the stat. i just needed to know if the right stat was being used and if it was being used right.

**mark beiser** · 09-19-2005, 08:57 PM

If it runs constantly with the thermostat in place, but shuts off when you jumper the 2 wires together, there is a problem with the thermostat, it isn't closing the circuit.
Since it has a T87F thermostat, check the heat anticipator, if it is open, the AC won't shut off.

As others have said, ditch the sub-base, it isn't needed for that system, and could well be the cause of the problem.

**mark beiser** · 09-19-2005, 08:59 PM

Originally posted by 2hot2coolme
Somethings really screwed up there.
Split system with only 2 control wires, how long ago was AC installed?
Sounds to me like the sub-base needs to be there, & you need to pull 2 more wires to the stat.

Mobile home systems only use 2 wires to the thermostat.

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