How warm does it have to be outside for outside AC unit to run? What temperature for easy freon movement?

Question

I have been told that it needs to be at least 65*F for 24 hours before the freon will flow freely enough to run the AC unit without hurting it. How true is this?

The idea is that I'm trying to figure out if the AC unit works before I move into this new house. I've been told it needs to be 65* before I can run the unit to find out.

Answer 1

this is not true, computer room AC units run all year, with a special add-on part called a low-ambient kit. The main reason you don't run your AC when it is below 65 is because you can just open a few windows to cool down your house, rather than waste money running the AC.
as far as the freon flowing, R-22 (the most common residential refrigerant) has a very low freezing point. Outdoor weather conditions aren't ever cold enough to freeze it.

I thought of something else, you will want to make sure that the AC unit has had power supplied to it for at least 24 hours before runnning it in cold temperatures. It has a crankcase heater in the compressor that needs to warm the oil, to assist with startupn and prolong the life of the compressor. It does the same thing as a crankcase heater in a diesel engine.

You can test the AC in cold temperatures to find out if it works, take a thermometer with you to stick in a supply duct to see what the temperature is. it should be 15-20 degrees cooler than the temperature in the house.

Answer 2

Agreed, the outside temperature isn't a matter for whether or not the freon will work, because it will. But most people would simply open a window and get the free cooling rather then spend the energy to run the air conditioner.

Answer 3

My HVAC guy also says 65 degrees. If you're buying the home, I would ask for a warranty on the HVAC system as a condition of the sale. I bought a house and we got a one year home warranty and it only cost the seller $350. That was a few years ago but it might be worth checking into.

Answer 4

BS... run it when you're hot! run it to how you feel, t-stat thermometers are notoriously in accurate!