Air Conditioning - ac humming

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qtip

09-15-05, 06:04 AM

here is my problem. air in house is hot. Went outside and unit has a low humming sound. Blade does not turn. Any advise?

DNT1

09-15-05, 12:09 PM

A lot of units use a dual capacitor which controls both the condensor fan and compressor if niether the fan nor compressor is running when the thermostat is calling for cooling and unit is producing a humming sound it is likely the capacitor, replace it and report back.

qtip

09-15-05, 06:59 PM

a friend came by and we checked unit. We took panel off and pushed a switch and unit started. he said the problem is relay switch. Is this the same thing as a capacitor? Also cannot find name of unit. All it says is, SUPER HIGH EFFICIENCY 7000. On inside it says by INTER-CITY PRODUCTS? HELP!!!!

DNT1

09-15-05, 08:06 PM

Well if it was the contactor that he pushed and the unit came on, it is technically a electromechanical relay does it look like this? http://toad.net/~jsmeenen/contactor.html

Sambolino

09-18-05, 05:46 PM

I'm encountering similar problems. When the system calls for cooling, the outside unit 'hums' and the fan blades don't spin. If I start the blades spinning, all is well and the unit operates just fine. So, I'm guessing it's not the fan motor but the 'switch' that starts the fan motor. Is this a capacitor issue?

DNT1

09-18-05, 07:43 PM

Big S yours sounds like a capacitor problem check out this site for some capacitor info might help you locate yours http://www.yorkcapacitor.com/products-motor%20run.html

mattison

09-19-05, 05:14 AM

You need to get a voltage reading on the control side of the contactor to verify whether or not you have 24 volts present.

Sambolino

09-19-05, 06:21 AM

Thanks DNT1 and mattison! I'm expecting (when I open up the unit) to find a bulging capacitor. Since I can get the unit cooling by manually turning the fan blades (before the compressor cuts off), is this a 'start' cap issue? :confused:

mattison

09-20-05, 05:25 AM

Your problem indeed sounds like a capacitor. Make sure you turn off the power to the unit before getting in there and dischage the capacitor by shorting across its terminals with a well insulated screwdriver before touching it.