Posted: 6/24/2014 4:02:13 PM EDT
| So last year my ac unit went out. Home warranty company replaced it with a new unit. It worked great the rest of last summer and the couple times I used it this year,last time being a couple weeks ago. Today I turn it on and get a call later in the day saying its blowing warm air again. When I got home from work I turned it on, the unit was running, the large copper line was cold, I check the furnace and the heat is running at the same time WTF!. I looked online for solutions. Tried disconnecting the W wire at the furnace and it doesnt turn on at all. Tried twisting the R, G, Y wires at the thermostat and get the same ac/heat at the same time problem. Is my furnace board toast? Any ideas?? |
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No, pretty sure the ac is running fine its just something is causing the heat to run at the same time No separate relay for the a/c? If it's the board, you can probably cheat if the furnace has a purge motor [mid80 or 90% or greater] by unhooking the 120V wires to it at the connector or board. You need to find out if there is a call for heat through the thermostat before you replace the board. |
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The board in the furnace is wr, furnace is american standard freedom 90
The thermostat on the wall is a honeywell touchscreen. I dont see a heat pump/gas furnace switch on the thermostat, I read that could be a possible problem If it had been switched by accident. I might try to run some temporary new wiring to rule out a damaged wire between the tstat and furnace. |
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turn off the gas valve Havent tried it but I think theres a safety switch to turn the system off if no ignition is detected so probably wouldnt work. Temps arent too bad right now anyway. I wired the thermostat directly to the control board using some short wires. I got the same thing, with the air turned on I get a call for heat. With the heat on I get a call for heat. With the heat on but set below room temp I get no call for heat. With just the fan on I get no call for heat. Im thinking its the board, i guess ill have to order one and find out. I went through the settings to make sure the thermostat was in the correct heating/cooling mode. |
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This got it working without the heat with no call for heat at the board. Why did disconnecting the white at the thermostat not do the same? Quoted:
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for now disconnect the white wire from the furnace This got it working without the heat with no call for heat at the board. Why did disconnecting the white at the thermostat not do the same? Because the thermostat is likely bad and it's giving a call for A/C and heat at the same time. |