When i got the 93 olds with 29k , the air did not work. i never really messed with it, i just drove windows down.So the compressor and system really only have 29k miles on it as it has never run for me. I decided to see if i can fix this without spending a ton on it. I found the high and low side schrader valves leaking. I have not found any other leaks with dye. I am going to put a new receiver/dryer on it and see if it holds a vacuum. I see several on rock auto and advance auto has 3. They vary in price from $25 , $34 and a swivel top for $45. My question is , is there a big difference in quality of these. For this car after market are the only choices.