After Pulling A Vacuum To Check For Leaks On My Auto Air Conditioner Should I Release The Vaccum To Recharge?


4 Answers

Anonymous Profile
Anonymous answered
No you do not release the vacuum. The reason for pulling a vacuum is to rid the system of air and moisture.absolutely no atmosphere is to be let to enter the system. If you charge the system with out a vacuum it will create very high pressures on both the high and low sides and will not cool properly. And may blow hoses o rings etc.
Jimmy Walz Profile
Jimmy Walz answered
Do not release the vacuum as you will allow moisture to enter the system, while you have vacuum start adding freon until there is no vacuum then start the unit and continue to add freon to the required amount.
Gary Brickhouse Profile
Gary Brickhouse answered
Do not release the vacuum. Doing so not only lets moisture in but also air. You want the lines to only have refrigerant and compressor oil in them.

Now as to the answer prior to me. It is never impossible to liquefy and vaporize a gas at vacuum condition. Take a science class. There is no vacuum once the freon is in the line. A vacuum is the absence of matter. What he said is only correct in that you release the vacuum when you put freon in, but you put freon into a line set containing only a vacuum.

It's simple. Charge it while it's under a vacuum and you can't go wrong.
eye3 light Profile
eye3 light answered
You have to release the vacuum before charging the unit with Freon.
To understand why it is necessary? I give you a little explanation of Freon working

The purpose of the Freon is to take heat and boil out. Its boiling point is very low even at atmospheric pressure. It is filled under pressure so it is in the liquid form. When it takes heat from the room or compartment or from car (if air conditioner is in car), it boils out. Then it is sent to the compressor where it is pressurized and then to the condenser which it exposed to the atmosphere where gaseous Freon dissipates its heat and become cool & liquefy. Then it is sent again to the evaporator or expansion valve where it takes heat from room or compartment and gets vaporized.

Now you can understand why you need to release the vacuum. Because if you fill Freon under vacuum condition then it will not work because then Freon will be always in gaseous form due to lowering of its boiling point .It will not be in liquid form even after being compressed because its condensation or boiling point still be very lower .If it is not possible to liquefy and vaporize Freon at vacuum condition so it will not cool the air anymore..
thanked the writer.
Gary Brickhouse
Gary Brickhouse commented
dude, no. You are quite mistaken. releasing the vacuum will cause air and moisture to return to the lines which will in turn cause the ac not to work properly.
Gary Brickhouse
Gary Brickhouse commented
absolutely wrong dude. boiling point of freon is based on pressure of system. has nothing to do with vacuum or not at all. Good try but AC is my profession and they all work on the same principle.

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