2 wire thermostat & A/C


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Old 01-12-19, 12:58 PM
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2 wire thermostat & A/C

I just recently bought a 40year old mobile home....you can only use a digital thermostat to contol the heat and timing; you need to (re) install the mechanical contact switch thermostat to control the unit....mine has a red/green/white set of wires going to the outside condenser; I don't know what the green wire does...it appears inside the furnace as two sets of rgw....both have the green wire turned back, and not connected...so I'm puzzled...anyone have something to help this one? TY

repoman1122:^)|
 
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Old 01-12-19, 01:22 PM
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Welcome to the forums.

You tagged on to an A/C system thread in an A/C only forum but you are talking about heat.

So in order to answer any questions we to know exactly what you have. If it's only controlled by two wires it is an A/C system with no heat.
 
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Old 01-12-19, 03:37 PM
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Originally Posted by PJmax View Post
Welcome to the forums.

You tagged on to an A/C system thread in an A/C only forum but you are talking about heat.

So in order to answer any questions we to know exactly what you have. If it's only controlled by two wires it is an A/C system with no heat.
Hi Pete,
I was off base on using two different thermostats.......what I need to see happen is to swap the r/w pair AC with the r/w pair going to the thermostat, which does control the heat....but the issue is that you have to flip the switch on the furnace to "cool".......this automatically fires up the furnace blower and the condenser fan, btw, the heater pair show 28vac across them, when in "cool", 5-6 volts - coming from where i dunno, thought the step down txfmr only puts out 24-28vac.......:^)
 

Last edited by repoman1122; 01-12-19 at 03:38 PM. Reason: spelling
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Old 01-12-19, 03:46 PM
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You didn't post what type of furnace this is but it sounds like a Coleman furnace converted to A/C also. With a Coleman conversion....there may not be a cooling relay.

I'm still not following what you want to do. You have two thermostats..... one heating and one cooling ?
You want to move the cooling wires to the heating thermostat ?
If yes..... it needs to be a heating and cooling thermostat.
The heat wires connect to W and Rh.
The cooling wires connect to Y and Rc.
 
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Old 01-12-19, 04:50 PM
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I should have mentioned that I'm dealing with a Coleman 'Presidential 2', furnace control is no problem; but to get AC, there is a rocker switch on the panel to select either 'heat', or 'cool'. When you flip it to 'cool', everything starts working - great, ha......the AC has no way to shut off, let alone regulate the temp. What I need is a good schematic, a handful (maybe just one) of relays, and a thermostat, any one will do - 'cause they all do just one thing: Open or close a voltage or ground path - binary "on/off".
 
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Old 01-12-19, 05:43 PM
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I have a few diagrams but they are different. Those furnaces came one way and many people converted them so that the wiring doesn't match any diagram. There should be a diagram posted inside your unit. I found a few googling. Search " coleman presidential 2 wiring diagram "
 
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Old 01-12-19, 07:16 PM
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Originally Posted by PJmax View Post
I have a few diagrams but they are different. Those furnaces came one way and many people converted them so that the wiring doesn't match any diagram. There should be a diagram posted inside your unit. I found a few googling. Search " coleman presidential 2 wiring diagram "
Yes indeed there is a sticker schematic, confusing - and I'm 60 years electrical/tronic. I can use a 110v timer switch, so that when the unit panel switch is set to "cool", it must wait on the timer settings to engage the A/C system & furnace blower. Not perfect, but I'm not around a lot, and I don't want the place to roast, or chill out either, so I have some control over the A/C....
 
 

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