QuestionI charged my ac in my Yukon 2 years ago and it worked fine until the other day. The compressor would not come on, so I jumpered the pressure switch on the accumulator. This would engage the compressor but still would only blow warm air. There has to be a major leak somewhere, I just don't know where. This has a little over 90k miles and I can do the repair myself. I am thinking it is probably a compressor and am willing to replace. Should I use dye to check for leaks before I replace the compressor? I thought I could remove the hose block on the compressor and seal it off then pull a vacuum to see if the rest of the system leaks. Is this a good idea or is there other things I should do. Also, should I replace the compressor anyway with a new accumulator and orifice tube like the warranties state? I am kind of limited on time as I need it done within one week. I am just to cheap to take to service station.
AnswerDave,
I know the feeling, I'm about as tight as it gets when it comes to my wallet. Wish I could teach the wife and young'uns the same. First, if you replace the compressor, absolutely replace the accumulator. The orifice tube is not as necessary, but if it will void the warranty then I would definately do it. It is too cheap a part to void a warranty on a 300-700 dollar compressor.
If you jumped your low pressure switch and the compressor engaged, it is good to go. But you definately, like you said, have a leak. The easiest (and cheapest) way to find it is to pressurize the system with nitrogen if you have it, or even refrigerant in the system will cause enough pressure for you to be able to locate. But DO NOT use anything else, like compressed air. The mixture of compressed air, refrigerant, and refrigerant oil will at worst cause an explosion later in the life of the vehicle, or at the least cause hydrofloric acid to form inside your system. Either way... bad news.
So pressurize your system with no more than about 75 PSI of nitrogen, or charge some refrigerant into the system. Take a silmple spray bottle full of soapy water and start spraying down your lines. The compressor manifold and where lines connect with fittings, both of your pressure switches, and your low and high side ports are the most common locations for leaks. If it doesn't disclose itself at any of these, spray down your condensor and the lines running back and forth in between the fins. And if that fails... then take it to your evaporator(s). Your truck more than likely has rear air, so do not forget the lines runnign to your rear evaporator. What you are looking for is bubbles to form from the leak location. It may take a minute or so for them to begin forming (If you charged it last two years ago, then it is a very small leak) So after soaking the area, observe it for a moment before moving to the next.
Also, I almost forgot. A common place for leaks is also the rotating shaft seal on the front of the compressor, where the shaft extrudes, but often times you will not be able to check this, with the pulley and clutch in the way, without an electronic/ultrasonic leak detector.
Once you find the leak, make certain you pull a vaccuum on it for about 30 minutes, if not longer, before charging it back up.
I hope I helped you a bit. But in closing... your compressor is good, do not change it if it isn't necessary. Good luck.
