My mechanic says my 1999 GS3 with 115K miles is not building pressure correctly; stated is only around 100 lbs. when it should be around 300 lbs.

How can I tell if the expansion valve is faulty or if the compressor is bad/tired?
I've done several searches here, but most results are on older cars that are not 2GS.

Thanks in advance.

(Also, who/where is the best place to investigate for parts?)

 

For parts online... http://www.ackits.com/

They also support an auto A/C forum.

 

Surely other folks have had some A/C issues in the past? Anymore input?

 

Well, I bought an expansion valve direct from SparkPlugs.com for $36 bucks, and I found a used compressor from a wrecked GS3 with 70K miles and a 101 day warranty. The EV will be getting installed first, and we'll see what happens.