Coleman help

[hvacguy1075]

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]

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]

no sub base is needed

[Christheheatingdude]

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]

Originally posted by twilli3967
Remove the sub-base.

I got to learn how to type with both hands

[trane]

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

[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.

[smokin68]

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]

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

[Christheheatingdude]

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

[hvacguy1075]

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]

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]

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.

[trane]

a T87 will work but don't use the subbase.

[2hot2coolme]

Originally posted by mark beiser

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.

Gotcha!

[Christheheatingdude]

Originally posted by mark beiser

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.


What kind of mobile home system is that? Not a split system. At least not the ones that we install here. Just interested in knowing, not trying to be a smart ass.

[Twilly]

Originally posted by twilli3967
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]


Don't get off on all these rabbit trails, try what i've told you. Or you can leave the sub-base but the ac will work only in the heat setting at the stat. YOU must switch to ac at the furnace control panel....these older style furnaces only use to wires....I know this drive the rookies crazy when they first see it.

[hvacguy1075]

Mark
i checked the heat anticipater and it seems to be ok but somthing is definatly wrong with stat . i think i will put on a heat only stat and that sounds like it should do the job. the way i understand it is that the stat should be open for the ac to run and closed to turn off. now i am trying to think how the stat workes in the heat mode? excuse me but i am on a strong pain killer and not thinking to clearly so please bear with me

[trane]

Coleman split systems with A/C control package. You normally have to change the blower (comes with a heating only blower) and the controls in the furnace. All just plugs in and your ready to go without trying to pull more wires and adding relays.

[trane]

Originally posted by hvacguy1075
Mark
i checked the heat anticipater and it seems to be ok but somthing is definatly wrong with stat . i think i will put on a heat only stat and that sounds like it should do the job. the way i understand it is that the stat should be open for the ac to run and closed to turn off. now i am trying to think how the stat workes in the heat mode? excuse me but i am on a strong pain killer and not thinking to clearly so please bear with me

Like a normal stat, it just switches it in the furnace.

[hvacguy1075]

Chris
Its a colman split system with 2 wires to the stat the customer said he just bought the trailer the stat is old and has paint on it the same color as the wall so the stat has been there awhile i think the customer was maybe cycling the ac with the toggle switch

[hvacguy1075]

twill
that does make sence. well i believe i understand what is going on now. just never messed with trailer stuff much

[hvacguy1075]

Hey thanks everybody for helping me out i really appreciate it

[pipe threader]

I believe your stat is controlling a relay with a nc contract for cooling. left black relay. when stat ia made it will open relay contact shutting off ac. May have a stat not making up. Switch on furnace must be set to cool.

[dec]

Thats halarious, guys if you havnt worked on an older Coleman mobile home dont give advice. As some on here have said it is a two wire thermostate and is not controlled like your standard 4 wire thermostat. ac and heat are controlled in the furnace

[Edited by dec on 09-19-2005 at 11:07 PM]

[tinmantu]

If it's a two wire system then it has a heat/cool switch at the furnace....in heat mode, on make a the stat it sends a signal...in cool mode on break of the stat...there is a reversing sequencer inside the housing where the switch is (similar to a fan relay)...I replace a half dozen or so per summer.

[Jultzya]

Originally posted by twilli3967
YOU must switch to ac at the furnace control panel....these older style furnaces only use to wires....I know this drive the rookies crazy when they first see it.

Which is what we have been seeing here with all the posts to his question! :D

You guys really need to get out more. LOL

[2hot2coolme]

Originally posted by jultzya

Originally posted by twilli3967
YOU must switch to ac at the furnace control panel....these older style furnaces only use to wires....I know this drive the rookies crazy when they first see it.

Which is what we have been seeing here with all the posts to his question! :D

You guys really need to get out more. LOL


I try to stay outta trailer parks :D

[Jultzya]

Originally posted by 2hot2coolme
I try to stay outta trailer parks :D

WHY, you're just missing the good looking BABES! LOL

[mizearella]

Tinmantu hit the nail on the head.

[joeoilman]

no they don't. they're just like a residential system. that t- 87 should have a subbase & red to rh & rc,green ,white,& yellow. then yellow & black to the condenser from furnace. should be a manual somewhere for that unit. might help to do a little reading or pull the manual from their website.

[Jultzya]

Originally posted by joeoilman
no they don't. they're just like a residential system. that t- 87 should have a subbase & red to rh & rc,green ,white,& yellow. then yellow & black to the condenser from furnace. should be a manual somewhere for that unit. might help to do a little reading or pull the manual from their website.

Haven't seen many old systems, Eh?

[Twilly]

Originally posted by jultzya

Originally posted by joeoilman
no they don't. they're just like a residential system. that t- 87 should have a subbase & red to rh & rc,green ,white,& yellow. then yellow & black to the condenser from furnace. should be a manual somewhere for that unit. might help to do a little reading or pull the manual from their website.

Haven't seen many old systems, Eh?



He's a rookie, and he's ready to argue.....

[trane]

Someday he will be back on here saying you will never guess what I ran into today. A split system with only 2 wires at the stat, how can that be.

[hvacguy1075]

Update on coleman split system with 2 wire thermostat.
Went out on the call yesterday with brand new snap action heat only thermostat and wired it up and system is operating properly now. not to many companys in my area work on trailer equipment I guess thats why i dont have much experience on them but im on my own now and plan on working on them . its all money. and again thanks for the help.

[Twilly]

Your welcome.

[Jultzya]

Uh Oh, joeoilman is going to tell you that you must have been DREAMING! :D

[hvacguy1075]

Was not dreaming was wide awake and system working fine. imagine that with only 2 wires to the thermostat. seems like ya learn somthing new all the time even if its not new.
if you close your mind and stop learning you might as well hang your gages up.

[Jultzya]

Originally posted by hvacguy1075
Was not dreaming was wide awake and system working fine.

Did you miss the ":D" in the last post? :D

[hvacguy1075]

Didnt miss it