QuestionHi David,
I have a 99 Subaru outback and the a/c stopped working a few years ago. I finally got around to trying to figure out what the problem is and I've taken it as far as I (and my father-in-law) can. Here is what I have done (the clutch seems to engage fine). 1) Checked the pressure on the low side. Pressure was WAY over what it should be. 2) vented almost everything out of the low side and hooked up a can to recharge the system. Here it would only take a quarter (or less) of the can, still not blow cold. Started the car and stopped, checked the pressure again and it was back to WAY to high. It seems like there is a blockage or something, which is why it is only taking a little bit of recharge, then pressurizing so high after starting it again. Any ideas? Am I out of luck for a fix it myself repair?
Thanks,
Dennis
AnswerDennis,
When you were charging was the engine and A/C on? If it wasn't then that would explain why the pressure was WAY too high. When the compressor is not running the pressure inside the lines equalize so that the high and low side reads the same. The compressor is what circulates the refrigerant inside the system. As the refrigerant exits the metering device, this is where your low pressure is created.
If you had the compressor running while you were charging, and the pressures were still grossly high, that could mean alot of things. Is there a way for you to get me the actual pressures? If so I need your high and low side readings as well as the ambient temperature outside the vehicle when you take them. The readings I need are with the engine and A/C on and the engine pushing roughly 1500 rpms. This is the point that automotive compressors are designed to be operated.
The entire A/C system is designed around pressures. These alone are able to tell a tech many things.
Now if your compressor clutch was engaged and your pressure was still as high as you describe, that leads me away from a restriction in the line, as this would create a very low pressure in the low side line as the compressor pulls the refrigerant through and nothing gets through the restriction to take its place. I would be thinking more along the lines of the valves in your compressor, internally in the compresor manifole leaking internally and allowing your high pressure to bleed through them back to your low side.
That is why I need your pressures to be able to tell for certain. This could be a very costly repair, or it could be as easy as charging it the proper way.
I hope I was able to help a bit, if you are able to get me your pressures, I will be more than glad to help out to the best of my ability. Thank you for your question and good luck in everything.
As a footnote... you said that your second step was venting out some of the refrigerant. This is always a bad idea. 1. because refrigerant is a major cause of ozone depletion/global warming, and 2. Section 609 of the Federal Clean Air Act makes it illegal with fines of up to 32,500 dollars, and appearance in federal court with up to 5 years prison time. If a certified technician does it, it will also result in loss of his certification for life. Just something to think about. If you need to remove refrigerant, please do it the proper way and have it recovered by a certified tech.
