How to add Freon when the compressor isn’t running

What you need to know before you start adding Freon to your AC when the compressor isn’t running

Important AC Fact #1: It’s the refrigerant (Freon) that carries oil throughout the system to lubricate the compressor.

Important AC Fact #2: If your AC system is low on refrigerant, you have a leak, and when refrigerant leaks out, so does the refrigerant oil. So the AC system is now low on oil.

Important AC Fact #3: If the compressor doesn’t engage, you should first measure the static pressure (How to read static pressure) to see if the system is empty. If static pressure is at or near 0, your system is empty, there’s air in the system and even if you add refrigerant, it’ll never run right with air in the system. At this point you must leak check the system, fix the leak, get it evacuated before you can refill it.

Important AC Fact #4: If you jumper across the low pressure cut off switch in order to run the compressor while you add refrigerant, you’ll be running the compressor with no oil, which will destroy the compressor.

Don’t jump the low pressure cut off switch to engage compressor to refill a low or empty system. You can cause compressor damage.

How to add Freon when the compressor isn’t running

Your goal here is to increase pressure in the low side of the system so it’s above the low pressure cut off switch. Try this procedure

1) With the engine running and AC turned on to MAX, connect you DIY AC recharge kit to the low side port. Squeeze the trigger to add refrigerant to the system. Keep adding refrigerant until it stops taking any more refrigerant.

2) Fill a bowl with warm water and submerge the DIY refrigerant can into the warm water. That will heat up the refrigerant, raising internal pressure and forcing more refrigerant into the system. As the water cools, replace with more warm water.

3) Repeat until the compressor starts running. At that point you’ve forced in enough refrigerant to raise pressure past the low pressure switch cut off point.

©, 2023 Rick Muscoplat

Posted on July 7, 2023 by Rick Muscoplat