1995 A/C Problem

[Hirohi]

Hi, Recently I took my car to a local repair shop so they could fix my AC.They changed the evaporator. Right now when the car is cold, the AC will work(Sometimes it wont). When the car gets warm, I will start to listen to a clicking sound (relay), constantly, and it seems to be related with the RPM of the car. The location of the sound seems to be inside (not the compressor clutch). Right now i can think of 2 things, low gas pressure (which it seems unlogical due to the recent repairs) or bad thermostat.

I dont have to much experience with the car. So any help knowing, locating and/or fixing the problem is appreaciated.

Im adding the following information after the initial post:

- Today I went to the college parking (multilevel one) and i was able to listen the compressor engaging and disengaging at the same time of the relay clicking sound inside the car.

- when the car is hot the AC wont work, let it cool over night or during a couple of hours and it will work until the same problem happens again.

[sixseas]

Due to the repairs its hard to determine what they actually did. Two things come to mind. The classic situation when AC cuts during high ambient temps it due to overfill. The high side cutoff will turn off compressor when ambient is high when its cooler it relieves the pressure so it works again. Another possible is the coolant is contaminated with O2, nitrogen,propane etc. which expands at different rates triggering the high pressure cutoff as it expands. I would do a good evacuation at -29# for minimum of a couple hours and refill following ambient pressure charts closely.