Air Handler Motor Speed - http://www.hvacmechanic.com/ Forums
Original message
| handydandy
 |  "Air Handler Motor Speed"
, posted Sun 13 Jul 23:09  
I have a Carrier FB4ANF030 air handler coupled to a matching condenser unit for a residential central air-conditioning unit. Up until last year the unit worked just fine, very quiet, maintaining set point, etc. Then last year, the air handler acted as if the fan speed increased. A whistling sound in the return duct and a noticable increase of draft at the outlet registers. The whistling sound would go away if I removed the return duct grill. The air handler has a 3-speed motor. As installed, the medium speed tap was connected. I decided to run an experiment and connect to the low speed tap. Everything returned to normal even with the return grill replaced. So, I left it on the low speed tap. This year, the situation has returned - noisy operation and increase of air flow, even at the low speed tap. For some reason, this motor is running at higher than design speed operation. Normally, motor speed is determined by the number of poles designed into the motor, and the power line frequency. I do not know whether or not deterioration of the running capacitor can cause the motor speed increase that I am experiencing.
Any ideas out there?
help me
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Replies:
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| Houston204
| "Re(1):Air Handler Motor Speed" , posted Mon 14 Jul 00:22
For $30 you can measure that capacitor.
"Tip of the Day" Remember to remove power first.
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