Air Conditioning - Problem with inside blower
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mcleo662
05-06-08, 10:45 PM
Checked all the threads with "blower" in them and don't feel I've been able to find my answer. Sorry for the lengthy post but I wanted to fully describe the issue.
Have a Lennox outside unit and First Co air handler inside. Everything worked fine last year. This year, only the heat seems to work. The inside blower turns on & functions fine in the heat mode. Turn to cool and the tstat "clicks" on, condensor starts running, outside fan works fine and evaporator starts to cool (eventually icing, likely due to the lack of blower) but the inside blower will not turn on. Get the same reaction whether fan is in "auto" or "on".
maintenance:
brand new air filter on the inside unit...confirmed no blockage around the condensor.
wiring:
confirmed all wiring is at least correct, though I have not crawled into the attic to confirm every inch of wiring is intact. 4 wire tstat (Red - power with jumper between RC & RH; Green - blower; Yellow - cool; White - heat). Have tried removing the tstat to just connect bare control wires. Crossing red & white turns on the heater/blower ok. Crossing red/green or red/yellow or red/yellow/green gets only the condensor/ouside fan going but no blower.
circuit breakers:
have checked all breakers and none are blowing, though I have tried switching them off & back on just in case.
tstat history:
Initially had an off-brand digital tstat, replaced it with a RiteTemp 6025 from Home Depot (believe it's their store brand). It worked for a bit then would intermitently work (as described above). There is a plastic jumper to connect the RH & RC wires. I can "jiggle" this jumper, get a spark and the a/c & blower kick on fine...eventually turning off but not cycling back on again without this physical intervention at the jumper level. Believeing it to be a bad tstat, it was returned & replaced with a Honeywell digital. At first install, the Honeywell seemed ok, but 10 minutes later the blower shut off in the cool cycle and has never come back on.
replacement parts:
Have replaced the "peanut relay" in the air handler. There are 2 wires coming from the relay to the blower. The red wire supposedly handles heat operations, with the black handling cooling operations. There is also a yellow wire from the blower to a fuse on the air handler itself that I believe is a common wire. With either the old relay or the new one, I am getting the same response...everything works fine in heat mode but no blower in cool mode (though the condensor comes on fine). I have tried swapping out the red & black leads from the relay to the blower and both wires seem to be ok, however, only the "heat post" on the relay seems to be live (when in heat mode). The "cool post" on the relay never has any juice in any mode (again, either on the old or new relay). Also, while in cool mode, I tried touching the black (cool) lead to the green power wire while the green wire was connected to the relay and the blower fired up.
Of course, I'm not beyond the idea that I have either a bad brand new tstat or bad brand new relay, but that is highly unlikely (IMO). The only other device inside the air handler I can think of would be either the transformer (wired in after the relay) or the capacitor on the blower. Question is, could only part of the transformer be bad or only part of the blower capacitor be bad to cause the blower to not function in only the cool cycle? Is there something within the outside condensor which might trigger the system to send juice to the relay (& thus the blower) when in cool mode? Anything else I might be missing?
Have a Lennox outside unit and First Co air handler inside. Everything worked fine last year. This year, only the heat seems to work. The inside blower turns on & functions fine in the heat mode. Turn to cool and the tstat "clicks" on, condensor starts running, outside fan works fine and evaporator starts to cool (eventually icing, likely due to the lack of blower) but the inside blower will not turn on. Get the same reaction whether fan is in "auto" or "on".
maintenance:
brand new air filter on the inside unit...confirmed no blockage around the condensor.
wiring:
confirmed all wiring is at least correct, though I have not crawled into the attic to confirm every inch of wiring is intact. 4 wire tstat (Red - power with jumper between RC & RH; Green - blower; Yellow - cool; White - heat). Have tried removing the tstat to just connect bare control wires. Crossing red & white turns on the heater/blower ok. Crossing red/green or red/yellow or red/yellow/green gets only the condensor/ouside fan going but no blower.
circuit breakers:
have checked all breakers and none are blowing, though I have tried switching them off & back on just in case.
tstat history:
Initially had an off-brand digital tstat, replaced it with a RiteTemp 6025 from Home Depot (believe it's their store brand). It worked for a bit then would intermitently work (as described above). There is a plastic jumper to connect the RH & RC wires. I can "jiggle" this jumper, get a spark and the a/c & blower kick on fine...eventually turning off but not cycling back on again without this physical intervention at the jumper level. Believeing it to be a bad tstat, it was returned & replaced with a Honeywell digital. At first install, the Honeywell seemed ok, but 10 minutes later the blower shut off in the cool cycle and has never come back on.
replacement parts:
Have replaced the "peanut relay" in the air handler. There are 2 wires coming from the relay to the blower. The red wire supposedly handles heat operations, with the black handling cooling operations. There is also a yellow wire from the blower to a fuse on the air handler itself that I believe is a common wire. With either the old relay or the new one, I am getting the same response...everything works fine in heat mode but no blower in cool mode (though the condensor comes on fine). I have tried swapping out the red & black leads from the relay to the blower and both wires seem to be ok, however, only the "heat post" on the relay seems to be live (when in heat mode). The "cool post" on the relay never has any juice in any mode (again, either on the old or new relay). Also, while in cool mode, I tried touching the black (cool) lead to the green power wire while the green wire was connected to the relay and the blower fired up.
Of course, I'm not beyond the idea that I have either a bad brand new tstat or bad brand new relay, but that is highly unlikely (IMO). The only other device inside the air handler I can think of would be either the transformer (wired in after the relay) or the capacitor on the blower. Question is, could only part of the transformer be bad or only part of the blower capacitor be bad to cause the blower to not function in only the cool cycle? Is there something within the outside condensor which might trigger the system to send juice to the relay (& thus the blower) when in cool mode? Anything else I might be missing?