Air Conditioning - Questions About Fan In Air-Handler
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Go69
06-11-07, 08:33 PM
I came home today to find that the fan in my A/C unit (air handler) is not blowing. What have I done so far:
* Confirmed that the unit outside is working properly. The compressor is running, and the fan with the condenser is running.
* Confirmed that the power supply to the fan in the air handler upstairs is good-no tripped breakers or fuses. I checked the "LINE" side inside the unit with my voltmeter-checked out at 122V
* I read the wiring schematic on the inside of the air handler door and confirmed that when the thermostat is set in "FAN ON" mode, that current is getting past all of the safeties and switches and to the wires for the actual fan motor.
Here is where my questions start... There are a total of about 5 #10 wires running into the fan. According to the schematic the white wire is always hot, and then one of the other (BLACK, RED, YELLOW, BLUE) grounds out thereby closing the circuit and actuating the fan. I checked with my meter that the white wire was putting out 110 volts, then checked the BLACK wire as ground, and the WHITE wire as hot and I got only 99Volts going into the fan. The fan was humming but not turning during this test. I suspect the different colored wires are for different speeds of the fan?????
Is it possible that the capacitor is bad and won't allow the fan to start? How does one test a capacitor?
Would you recommend changing out the fan motor first, or the capacitor? I checked the capacitor and it does not appear to have rounded out the bottom of the can... I know it can still be bad even if the can is not distorted. If I could test it, it would help me with the process of elimination.
I am going to try and fix this myself if possible. Any help anyone can offer would be greatly appreciated.
* Confirmed that the unit outside is working properly. The compressor is running, and the fan with the condenser is running.
* Confirmed that the power supply to the fan in the air handler upstairs is good-no tripped breakers or fuses. I checked the "LINE" side inside the unit with my voltmeter-checked out at 122V
* I read the wiring schematic on the inside of the air handler door and confirmed that when the thermostat is set in "FAN ON" mode, that current is getting past all of the safeties and switches and to the wires for the actual fan motor.
Here is where my questions start... There are a total of about 5 #10 wires running into the fan. According to the schematic the white wire is always hot, and then one of the other (BLACK, RED, YELLOW, BLUE) grounds out thereby closing the circuit and actuating the fan. I checked with my meter that the white wire was putting out 110 volts, then checked the BLACK wire as ground, and the WHITE wire as hot and I got only 99Volts going into the fan. The fan was humming but not turning during this test. I suspect the different colored wires are for different speeds of the fan?????
Is it possible that the capacitor is bad and won't allow the fan to start? How does one test a capacitor?
Would you recommend changing out the fan motor first, or the capacitor? I checked the capacitor and it does not appear to have rounded out the bottom of the can... I know it can still be bad even if the can is not distorted. If I could test it, it would help me with the process of elimination.
I am going to try and fix this myself if possible. Any help anyone can offer would be greatly appreciated.
mattison
06-12-07, 05:24 AM
For probably less than $10 bucks you can put in a new capacitor.
Go69
06-12-07, 07:57 AM
Okay. So you think it is the capacitor. That gives me a place to start! Thanks very much for your help!
Oh wait, I have another question. I know capacitors can be dangerous because they store voltage. How can I drain before handling it??
Oh wait, I have another question. I know capacitors can be dangerous because they store voltage. How can I drain before handling it??
Go69
06-16-07, 04:42 PM
***UPDATE****
I replaced the capacitor-$9.31 w/tax and my system is up and running again.
I replaced the capacitor-$9.31 w/tax and my system is up and running again.