I have a 93 gmc shorty. Today i bought and installed new seals on the back of the compressor where the hard lines mount. When i went to charge the lines its still leaking there. I cleaned both surface areas before installing and double checked the seal part number. I am scratching my head now, any ideas on whats causing this?
Are you sure it's the lines/connection that's leaking? There is a plug (held by a cir-lock clip) in the rear of the compressor that has a o-ring seal. If you have a rear brace that connects the compressor to the intake manifold that plug will be hiding under it. Take out the two bolts holding the brace and you'll find it. (It will look similar to a small freeze-plug under the cir-lock.) I have had this spot leak many times before and drive an electronic leak detector nuts.
Last edited by CatFish; October 19th 2018 9:17 pm. Reason: kant spel
If you can find, buy, borrow the equipment. Use a good set of gauges, and a vacuum pump, Pull a vacuum in the system, while it is pulling down tap on the compressor now and then to get any gas in the oil out (it will ruin the test). Pull it down to -28 on the low side gauge and let it sit for 24 hours. If it holds no leaks! While a pain in the ass, it's worth it to pull the compressor so you can look for problems. If you take it out change the oil The plug that Catfish mentioned. Keep in mind you have to use right oil for what ever gas you decide to use, the same goes for the seals on the refer lines at the compressor. I got a new compressor for my 89 and it came with a mixed bag of seals. They varied from gas used to type of refer line block it has.