Heat pump thermostat problems
#1
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Join Date: Aug 2008
Location: California
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Heat pump thermostat problems
I had what I thought was a simple thermostat installation and have the following problem. Lost 24Vac between the common and red wires/terminals. This is a heat pump with 7 wires with the following terminal - wire list:
G - Green, Y - Yellow, E - Blue, W2 - White, C - Brown, O - Orange, R - Red.
After I connected everything to the new Honeywell terminals and plugged the thermostat; the screen was blank. I called customer service and they said probably not enough voltage to power the new thermostat. I checked voltage between the Common -C and red wire to find no voltage. I reinstalled old thermostat exactly as removed (I have a photo of original) and as expected it doesn't work now because there is no power between C an red terminals. My heat pump is an old Day an Night unit made by carrier. What can be the cause and anything I can do before calling for service?
G - Green, Y - Yellow, E - Blue, W2 - White, C - Brown, O - Orange, R - Red.
After I connected everything to the new Honeywell terminals and plugged the thermostat; the screen was blank. I called customer service and they said probably not enough voltage to power the new thermostat. I checked voltage between the Common -C and red wire to find no voltage. I reinstalled old thermostat exactly as removed (I have a photo of original) and as expected it doesn't work now because there is no power between C an red terminals. My heat pump is an old Day an Night unit made by carrier. What can be the cause and anything I can do before calling for service?
#2
Member
Check the fuse on the control board in the furnace. If you didn't shut off the power to the furnace you probably shorted the wires.
#4
Welcome to the forums.
We haven't heard back from the OP in a while so maybe he figured out the problem.
Since he has a heat pump he's not likely to have an actual control board like a furnace would have. He could possibly have a fuse but more likely the transformer has been shorted and is fried.
We haven't heard back from the OP in a while so maybe he figured out the problem.
Since he has a heat pump he's not likely to have an actual control board like a furnace would have. He could possibly have a fuse but more likely the transformer has been shorted and is fried.