Blower fan works in A/C but not heat
A couple of weeks ago my Lennox G20Q3E-75-1 was acting up. Gas valve was cycling when calling for heat and then once satisfied and the main burners went out the pilot light was staying lit. I thought it might be the flame sensor as far as the gas valve cycling and didn't want to tear into it so I had a tech come out. He removed the sensor, cleaned it and reinstalled. Worked almost OK but the pilot was still staying lit. The pilot should go out the same time the gas valve shuts down on this unit because of the electronic iginition - yes? Determined that the gas valve was sticking so I gave it a tap and pilot went out and the problem hasn't reoccurred since then. Now this morning the blower motor will not cycle on after the burners are on for a short time. I think it high temp limits out and then shuts down the gas valve. I can hear and feel the relay on the circuit board clicking but don't know if power is getting transferred to the blower motor from the relay or not. Blower does not work in either auto or continuous fan mode. I switched from heat to A/C, lowered the temp so the A/C would come on and the blower comes on normal in both auto and continuous fan mode. Is the relay for the heat cycle on a different relay than the A/C which is causing the problem or should I try and change the blower speed wiring to see if that would work. Don't want to burn out a board if I miswire something or what else could be wrong? Any help would be appreciated!
Same problem but it is Honeywell. What should I do?
Hi Labman,
I just got the same problem as Brad, except mine is Honeywell with 2 zones. I went to attic and checked out the system: when I turned on zone one (or two) with AC or FAN, they worked OK as expected. But when I turned on HEAT, the lights indicated correctly and the system turned on and run, then I heard some kind of sizzling sound (like gas coming out) then it runs for 1 minute and turned off without any air blowing out. I tried to unplug and also press the BOOT button but it did the same thing. The first time I did it, it seemed to work OK with heat blowing out but since then it never worked again. What should I need to do to have the heat turn on again? Probably, the gas was not burnt because it was not lit (like the water heater) or something, if so where do I need to light it? Does it have any pilot light somewhere I need to light or ignition switch somewhere I can clean up? Do I need to clean up something? Please help. We did not have heat for several nights now... It really worries me because when the unit runs for 1 minute and stops, I smell some gas. Any help would be appreciated. It is 2 year-old gas central-heat system.
Thank you very much in advance.
FC:p