My buddy was servicing his air conditioner the other day. He has a '97 with R-134A. Anyways, he was using a guage to monitor how much freon he was putting in. This guage was for R-134A vehicles and plugged right into the low side refill nozel. His guage read in P.S.I. and he put around 35 p.s.i. in his truck. Well, my air conditioning has not been working to good, it takes forever to get cold. So we hooked that guage up to my truck and it read 65 p.s.i., which the guage reads as being way too high and even emphasizes it with a red label and a warning. I know the engine label says we are supposed to have 34oz., I think, but does anybody know what that equates to in p.s.i.? Or is this guage not accurate for our trucks, are they supposed to have that much freon in them? Is this something where I need to take time out of my day and have the dealer look at it?

 

In order to fill the system to the appropriate level, in your case 34 oz., a machine must be used which first removes the freon and measures it by weight, and then puts it back into the system to the proper level. Measuring by gauges on an automotive A/C system is not very accurate, there are far too many variables involved as far as what the pressures should be at (ambient air temp, refridgerant temp, vehicle interior temp, engine temp, etc). My suggestion would be to get it to a shop where they have the proper equipment to service automotive A/C systems.