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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22511
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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My central AC unit has been having some problems over the past

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My central AC unit has been having some problems over the past week. I initially noticed the unit would run and the an on top would blow on the outside unit but no air came through the vents inside. If I turned the unit off, waited two or three minutes and turned it back on, it worked fine. I called a service tech--he came and checked the fan blower motor, the capacitator and the freon levels. He said the freon was low and that there was a leak. He added freon but said it would be too expensive to repair a leak on a unit this old.

This morning the problem happened again, only this time I could not get the indoor fan to start. I tried several times (waiting five to ten minutes in between) but I couldn't get anywhere. I finally decided to switch the unit to heat mainly out of curiosity. It worked normally. I let it run for maybe ten minutes and shut it off. After waiting a few minutes, I tried the air again. It is now working.

I am contacting the technician tomorrow but I was hoping to have some suggestion for him as I'm sure the unit will be behaving perfectly when he arrives. Another expert from this site recommended the relay be replaced? Does that still seem reasonable given the behavior when switching to heat?


My name is Billy

Do you have the make and model of the indoor unit?


Customer: replied 3 years ago.
I don't. The thermostat says GMC and I know the unit was installed in 1996 with new duct work in 2008. That's, unfortunately, all I know.

The reason I wanted the indoor make and model of the blower unit was that I could be very specific with the part number.

In your case you are correct. If blower works in heat and fails in cool means a blower relay is bad. On newer units this relay is on a circuit board which means the circuit board itself must be replaced.

Once in the unit the tech can easily identify if relay or circuit board...but that issurely your issue.


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Customer: replied 3 years ago.
I had the technician come out again and I asked him to check the circuit board and the relay. He said both were fine, but that unless he problem was occurring at that moment, he would not be able to tell. He also said the leak was in the main coil and that we would be looking at about $900 to replace the part and then the cost of charging the unit with freon again.

I am so frustrated. I don't doubt there is a freon leak, but that is not what is causing the problem. Even after he added freon, the problem remains. Also, am I incorrect in assuming that a freon level low enough to cause the unit to lock up would also cause the unit not to cool as well? The air coming from the vents measures at between 52-56 degrees and always has.

The tech keeps saying the machine is not worth fixing and that may be true, but I have another tech coming out today. I just want to make sure I don't sound completely uneducated.

The unit is a 1996 2.5 ton. We have been quoted prices ranging from 3680-3900 for replacement. What is your opinion on replacing a coil in a unit of that age? Thanks.

Has the leak ever been found?

Has the tech daid where the leak would be. Before adding frigerant the tech is to identify and repair. BUT..if you have consistantly been blowing 52-56 degrees I do not think loss of freon is an issue. 15 degrees cooler than room temp is what we are if the room is 75 we want at least 60 degree air coming out.

I would see what the next tech says because something is not adding up.

Customer: replied 3 years ago.
He said the leak was in (I think) the main cooling coil. He said every time the air runs the freon will leak and that running the heat will cause it to leak more. I don't know enough about it to argue with him, but I just couldn't understand why a freon leak wouldn't cause a cooling problem.

Thank you so much for the numbers. I'm expecting the new tech today around lunch. Hopefully he can figure this out.

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