Ac Heat And Fan Does Not Come On - HVAC - DIY Chatroom Home Improvement Forum

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Old 04-22-2012, 04:27 PM   #1
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Ac heat and fan does not come on

I had an old mercury thermostat that seemed to stop working, so I went and bought a honeywell rth221 thermostat from home depot. I installed it by following the manual but the ac heat and fan will not come on. I'm sure I connected the wires correctly because I looked at them before I disconnected the old one and the colors correspond with the letters green-g yellow-y white-w red-r. But now I am doubting I connected it correctly. The thermostat is telling me the temperature but I cant seem to get the unit to turn on. I want to try and figure out the problem myself before I have to spend money on calling a technician. Please help with any possible solutions.


ceejay702 is offline   Reply With Quote
Old 04-22-2012, 04:44 PM   #2
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It's possible you blew the fuse on the control board in the furnace if you did not turn the power to the furnace off prior to doing any work.The red wire on the R terminal is your 24 volts.

Lucky for you it's just a simple spade 3 or 5 amp fuse you can pick up from any auto parts store or if you have an extra in your vehicles fuse panel..

Try checking for that and let us know.


Doc Holliday is offline   Reply With Quote

air conditioning , fan won't turn on , heat

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