by tashirosgt, May 20, 2006
I want test the AC on my '89 Corolla for leaks. I have the test kit and some manifold gauges. The system was converted to R134a several years ago. If I find that most of the refrigerant is gone, is the contents of the can with the dye enough to pressurize the system for a test? Is there some minimum pressure that I need to get a useful leak test? Or must I put refrigerant in the system to bring the low pressure side up to spec before doing a leak test?
You should be able to leak test it with the pressure from the can. If your leak is pretty significant then DO NOT use refrigerant to find it. Intentionally leaking refrigerant into the enviornment can cost you $$$ in fines. If the leak is minor then it's no big deal. If you have it available to you, use an inert gas like Nitrogen to bring up the pressure for the testing. Of course you'll only want to do that after you have properly evacuated the system and recovered all of the remaining refrigerant. As for minimum pressure for a leak test it depends on what you use. I know for a home system I would bring the pressure up to about 80lbs on the low side.
you check for leaks by pulling a vacuum (30 inches of water i think, maybe Hg) and then watching that the needle doesnt move for atleast 5 minutes.
