[TX3100Guy]

As a follow-up, the short version of the story is that I had to replace the evaporator coil since the threads on the copper pipe fitting were stripped. After convincing Classic Air to sell it to me (since I wasn't the original owner/installer of the system, they required proof of ownership, which fortunately several photos of the unit sufficed), I installed the evap unit and reinstalled the unit in the car.

After a successful overnight vacuum on the system, I proceeded to charge the system by weight of the cans on a postal scale. The part that seemed strange to me was that once the refrigerant began entering the low side port (high side closed), I immediately saw an increase on the low side and slow but steady increase on the high side. However, the low side needle moved slowly and deliberately as the charge was entering, but the high side needle was wiggling wildly +/- 10 psi. It moved up from zero to 150 +/- 10 psi and the car was blowing cold. Not frigid, just cold - colder than ever in the past.

Once I had entered the amount of refrigerant that is called for (24 ounces) the gauges were about 29 psi - low side and 150 psi +/- on the high side. Mind you I was in a 75 degree garage, but with the garage door open since the car was running (nearly 100 outside in Dallas).

Is it normal for the high side gauge to be bouncing around while building pressure or is the compressor showing signs of a problem?