My A/C unit has been depressurized since I bought the car almost 8 months ago. I just graduated college so I now have time to actually break into it and fix it. I understand the basic principles of how A/C works but each car is slightly different so I need help from someone with experience in this area on third gen F-bodies. I don't know what is leaking or if the compressor is shot yet since it is R-12 equiped and I can't afford the $30 or so per pound of R-12 for testing purposes. I also know that before I change over to R-134a I need to evacuate and clean the old oil from the system. My question is, is there anything else I need to do or be careful of before switching refrigerants? (I know I need the R-134a valve adapters) Also, how much (approx.) does it cost to have the system cleaned and evacuated?

Thanks in advance

 

Take it to a shop and have it done correctly. Before any conversion is done, the leak needs to be located. The system will be pressurized with 300 psi of nitrogen to find any leaks. If everything checks out, the conversion isn't that hard to do if you have an AC machine. All the o-rings and adaptors are available in a kit.

The dryer needs to be replaced (aluminum cylinder near the firewall). All the o-rings in the system should be replaced. Any oil in the compressor needs to be dumped out and filled with R134a compatable oil. Adaptor fittings are installed on the high and low pressure fittings so that R134a couplers can be used.

After that it's just a matter of sucking down the system into a deep vacuum and charging it back up with R134a. You don't want any air in the system.

A proper AC repair is not possible for a back yard mechanic since they don't usually have access to an AC machine. Typical cost to do a complete conversion is $200-$300

 

Chances are that the leak is from one of the O-rings or the compressor itself right? Couldn't I replace the dryer and rings, drain the compressor oil, and change to the R134a compatible fittings myself and then take it to the A/C shop to have the air sucked out and refrigerant filled?

 

Whats the problem with having air in the system when adding refrigerant? I understand that this will make the A/C run less efficiently but will it do any damage?

 

Air is considered a contaminate in an AC system. It has moisture in it. When compressed, it heats up and doesn't allow the AC to work as efficent because the air creates more pressure than what the AC system is designed to work at..