Air Conditioner Growl

[Tarpman]

I have a question about my a/c system. I had to change my a/c compressor in the summer, because it actually blew apart while driving. I changed it and the receiver dryer (I think, the silver canister) and also orifice tube (filter). My friend took to his shop and evacuated system and refilled. Ever since then at idle or low RPM like backing out of parking spot or even going straight it growls and makes the truck shake. I know its the a/c because it doesn't do it when its off. It doesn't do it all the time but most all. When it first happened I looked at the compressor and saw the green dye that had leaked out of relief valve. It doesn't do that anymore. There were metal shavings in old filter. Any help would be appreciated. Also it has rear air if that makes a difference.

 

[JFF]

For the fact that you saw leakage from the relief valve would indicate to me that you have too high of pressure on the high side of the system causing the valve to leak. This can be caused by a restriction somewhere in the system, not evacuating the system properly to remove all non condensables or overcharging the system. Changing the filer dryer (silver canister) and orifice tube (long plastic piece with a filter on the end) was the right thing to do since this is where the shavings can get trapped and affect the performance of the system. I would suspect that the rear system has some blockage in the orifice causing the problem. Make certain that you keep the vacuum pump on long enough to remove all non condensable before charging the system. Also, take your time charging the system and start with a under charge condition adding refrigerant a little at a time until you see beads of sweat on the low side piping where it goes into the evaporator and you get a good discharge temp.