Help needed with an old A/C unit


Old 08-07-19, 04:03 PM
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Help needed with an old A/C unit

Hi! I'm new to the form and I'm hoping someone can help with my issue as I had an AC company come out and want to charge $85 for a capacitor which I know costs around $12. Unit is very old and the capacitor was replaced around 2 yrs ago. A friend who is an extremely experienced electrician tested the contactor and found no issue. The fan works, it is blowing air (not super cold air). The issue is that the compressor is making a very loud buzz every so often. We timed it; it started out at being every 40 seconds and the longer it ran, it got up to 1 min. 48 seconds. It is the same noise each time. If anyone has had a similar experience or can point us to things we can check, it would be greatly appreciated!! It is a unit for upstairs and while we don't use it often, we can't have family visit because of this. I did some research and the main things that seem to come up are the capacitor, contactor, and the disconnect switch. Thank you very much in advance for any feedback/help!
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Old 08-07-19, 06:49 PM
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That is a classic case of being low on refrigerant.
There is a low pressure switch that will shut down the condenser if the charge is low.
Old 08-07-19, 07:43 PM
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The guy that came out didn't even check the refrigerant. Thank you! I seem to be having one of those months where everything in the house is going wrong.
Old 08-07-19, 08:55 PM
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It sounds like a bad capacitor to me.

Did your electrician friend tell you the rating of the capacitor?
Did he also tell you what your capacitor measures?

I suspect that the answer to both questions is no.

Replace your capacitor.

I cannot check the refrigerant charge of a condenser with a bad run capacitor.
Old 08-08-19, 09:34 AM
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when u say compressor, are you referring to the entire outdoor unit (fan and compressor cycling) or the actual compressor.

try to use the right terminology.
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