We bought our house in April and ac/heat pump is 11 year old comfortmaker. Works great but the unit outside always makes a high squealing sound for about a minute and does it about 2 or so before unit starts to run. I had an ac tech look at it when we moved in and told him about the sound. He checked the pressure and said it s more than likely a very very small leak in freon line and that it would be impossible to locate. Does that sound correct? AC and heat work great but that noise is awfully loud and very high pitched. And it doesn't t happen when the unit is running or afterwards... only within a minute or 2 of running. Any ideas?

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He checked the pressure and said it s more than likely a very very small leak in freon line and that it would be impossible to locate.

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Does that sound correct?

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Not to me, it doesn't.


If this is not the condenser fan squealing on start up because of corrosion on the shaft and bearings, which is highly unlikely, I would guess that it is the terminal expansion valve. That is assuming that it has a expansion valve and not a cap tube.

In other words the unit is probably over charged and the high side pressure is so high upon start up that the valve vibrates.

Have another ac tech check it out for correct pressure.

I can assure you it is not because of a leak.