furnace fan control not controling

[henrysgarage]

I hooked up the thermostat with 4 wires as per the lettering on both the thermostat and furnace but the furnace starts to run on heat no matter what thermostat setting I use. When I set the furnace off at the thermostat the fan runs on high until I turn the main power switch off. I am sure I have the thermostat on GAS. Thanks.

The furnace is a Rheem gas/ now propane. Classic 90 PLUS Premium plus

The thermostat is programmable.

1) what do I do to wire the thing correctly(besides paying someone)

2) how do I select the low speed so I can circulate the cold air from my window A/C.

 

[alecmcmahon]

I hooked up the thermostat with 4 wires as per the lettering on both the thermostat and furnace but the furnace starts to run on heat no matter what thermostat setting I use. When I set the furnace off at the thermostat the fan runs on high until I turn the main power switch off. I am sure I have the thermostat on GAS. Thanks.

The furnace is a Rheem gas/ now propane. Classic 90 PLUS Premium plus

The thermostat is programmable.

1) what do I do to wire the thing correctly(besides paying someone)

2) how do I select the low speed so I can circulate the cold air from my window A/C.

is this a new install or replacing the t-stat?

If your going by t-stat wire color that may be your problem, different people use different color wires for hooking to the thermostat.

I'd guess you hooked your wires up wrong.

 

[henrysgarage]

I installed the furnace myself and had a tech do the final propane hook up and test to comply with code. I have been running the furnace for 4 years on heat and wanted to run the fan as I said in my opening post. The wire colour is as stated on both units as I did it by the letters at both ends, so there is no crossing of the wires.

 

[HVAC Phil]

If the wiring is correct, there must be a problem with either the tstat or control module (or a short on low voltage stat wires). What kind of stat? it isn't one of those quality stats from home depot is it?

 

[mrobins297aaa]

check to make sure that the red wire isn't touching the white wire somehow either in the stat or inside the furnace.........white is the heating wire, so somehow its getting power, if the wires aren't touching than maybe its the stat. check the stat wires real close at the thermostat to make sure when the insulation was stripped back they didn't cut and expose the bare copper. If you have the fan in the on position and somehow the green wire(the fan wire) is touching the white wire the heat will start.

 

[mrobins297aaa]

running that furnace fan to try an circulate air from your window ac is one of those things that sounds good but just doesn't work very well in the high or low speed.
why don't you just run the fan on high (the way it is hooked up from the factory when you turn the fan on from the thermostat) and see if that works first?

 

[brewchief]

Disconnect the stat, make sure none of the wires are touching each other and turn the power on, at this point nothing should happen. Now connect the white to red, heat should come on. Disconnect the white and touch the red and green, now you will get either low blower speed or high(A/C) speed, this is dependent on the furnace model, some will bring high speed on with a G call and others G will bring on low and a call at Y is required for high speed.

If anything happens with the stat disconnected then repeat the same test at the furnace board.

Furnace and t-stat models will help out a bit also.

 

[henrysgarage]

Well, I found that some wires were shorted together, now all works fine, thanks all.

 

[Chloe Taylor]

The motor of the fan might have burned.... Get it replaced with a new one....