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Old 07-06-2009, 09:39 AM  
chicagomike
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Default HVAC fan not working

The other day on a hot night the power went out intermittently and I was only getting about half power... the AC would not run and the microwave was not working at full power. I flipped some circuit breakers figuring that there was a problem in my house, but then I discovered my neighbors had the same problem as a transformer had blown. After the electric company replaced it, my upstairs HVAC fan would did not work. The compressor would kick on, but the air would not blow through the ducts. The fan would not work if I set it to "on", turned on the AC or the heat.

1) I have two seperate systems for the upstairs and downstairs. The downstairs system works fine.
2) I spun the fan by hand it it spins freely.
3) I checked the capacitor, and it works fine. (I swapped it with the downstairs unit, which is identical).
4) I now want to check the contactor as described in this post below, but I do not know where the contactor is or how to get to it.

www houserepairtalk com/f8/york-hvac-blower-not-working-871/ (replace spaces with . )

I have the York system described in this diagram:

www yorkupg com/PDFFiles/035-20370-001-B-0405.pdf (replace spaces with . )


Any suggestions on how to find the contactor or what else I should try?



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Old 07-06-2009, 10:27 AM  
kok328
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Don't believe everything you read. You unit does not have a contactor for the blower motor.
Check to see if your getting 24VAC between common (ground) and the green wire where the thermostat wires terminate inside the cabinet (with T-stat fan set to ON). There maybe a safety switch that kills power to the internals when you remove the panel. You'll have to "make" this switch manually while troubleshooting. If you find that voltage does exist at this point, then you maybe looking at a fried or stuck relay on the circuit board that triggers the blower to come on. A few light taps on the relay may un-stick it but, no guarantees. If this is the case, you should be able to locate a like rated relay and replace it rather than replacing the whole board.



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Old 07-06-2009, 11:09 AM  
chicagomike
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Thanks KOK for the suggestions. I will try it tonight when I get home.

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Old 09-22-2009, 09:04 PM  
matty123
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Quote:
Originally Posted by kok328 View Post
Don't believe everything you read. You unit does not have a contactor for the blower motor.
Check to see if your getting 24VAC between common (ground) and the green wire where the thermostat wires terminate inside the cabinet (with T-stat fan set to ON). There maybe a safety switch that kills power to the internals when you remove the panel. You'll have to "make" this switch manually while troubleshooting. If you find that voltage does exist at this point, then you maybe looking at a fried or stuck relay on the circuit board that triggers the blower to come on. A few light taps on the relay may un-stick it but, no guarantees. If this is the case, you should be able to locate a like rated relay and replace it rather than replacing the whole board.
sorry to say but i think this is very risky.. if we did any thing wrong by mistakenly will get in huge trouble.
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Old 09-23-2009, 03:11 AM  
Maverick7687
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I am going to go out on a limb and say that if you have checked the Cap and it is good, there is power to everything else, it could either be the Fan Relay/Control board or the fan motor itself. Just because it spins freely doesn't mean it's good. Hook an amp clamp up to the fan motor and see if it tries to start. If not, my guess would be relay/Indoor Fan board.

Kok is correct: No Contactor for Indoor Blower.
If you take the route of checking the T-Stat wires make sure you don't short any of the 24v wires to ground. Sometimes it just kills a fuse (If you're lucky enough to have the right one there) and other times it could kill the whole 24v control board.



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