AC below 60 degrees

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John K
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Joined: Sat Nov 26, 2011 9:43 am

AC below 60 degrees

Post by John K » Sat Nov 26, 2011 9:49 am

Hi All, I would like to know about running Air conditioning when the outside temperature is too cold. I'm a Home Inspector and have understood that you risk damaging the compressor if you run ac when its been below 60 degrees for a period of time. I believe I understand the reasons for possible damage. I'm not clear on where this guidelince came from. Is it a manufacturers spec? Is it a general rule of thumb? or is it Home Inspector Folk Lore?

I would appreciate your help on this, inclucing where I might find documentation..

Thanks John

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- AC below 60 degrees

Post by Freon » Sun Nov 27, 2011 10:39 am

I think the worry with a split system AC (household, not auto) is the return to the compressor of liquid refrigerant. A compressor only compresses gasses, not liquids. As the heat load on the evaporator coil lessens, less refrigerant is boiled since there is less heat being transferred to the refrigerant in the coil. At the same time, the outdoor compressor is condensing almost 100% of the refrigerant due to the lower ambient temperature.

Now in cars, you can run the AC at low temperatures and we do for defrosting. A car's split system has an accumulator to collect any liquid refrigerant returning from the evaporator coil before it goes to the compressor.

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- AC below 60 degrees

Post by heatseeker » Mon Nov 28, 2011 8:42 am

just install a sump heater on the compressor. Is this cooling a computer room? Is it cooling your house ? what is the application?

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- AC below 60 degrees

Post by MTI STUDENT » Sun Dec 04, 2011 12:45 am

He is a home inspector I believe he is asking in General to check systems in homes he is inspecting . We are taught there is no good way to test proper ac in a split system in cold weather . To do a proper check it needs to be at a higher temp so you can have a load on the system.

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- AC below 60 degrees

Post by moshei » Thu Apr 12, 2012 9:20 am

I agree,,,you must put it on it's standard temp and install a sub heater as well..!..,
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