A/C squeaks, how to diagnose???

[myhilo]

93 Subaru Loyale

vin: JF1AC4226PC200963

EA82 1800cc 4 cyl.

Automatic 3spd

 

A/C belt? squeaks, sounds like a belt about to break so we always turn of a/c at dash, stops right away. Turn on A/C again doesn't squeak for a while.

 

How can I track down the problem, the belts at the A/C compressors don't look bad. I converted the A/C to 134a last summer, all went well, cools fine but occasionally the 'squeak' happens, scares the heck out of us so we immediately turn off A/C. Have replaced the 4 wire connector at the pressure switch by the passenger (Rt) side headlight. The squeak is very unpredictable, the A/C will run for 20 minutes, or 5 minutes before squeak. Never on startup of A/C.

 

Again, How can I track down the problem, the belts at the A/C compressors don't look bad?

[GeneralDisorder]

Sounds like the compressor is locking up or the belts are slipping due to abnormal load (high torque at the compressor). That could be from the compressor being "slugged" with liquid refrigerant (too much charge? R134 requires less system pressure than R12) or an internal mechanical problem. Might be the a bearing in the compressor.

 

Next time it squeels like that - instead of shutting it off, quickly get under the hood and observe what is happening. If the compressor is slow or stopped then you know what the problem is.

 

GD

[idosubaru]

overcharging the system will make it scream. if you've converted it, the system requires less R134a than the old stuff. i think it's been said it's like one third? 9 ounces instead of 27? either way, overcharged can cause your symptoms and conversions can cause it. check the pressures.

 

a/c belt

a/c clutch bearings

a/c compressor

 

a mechanics stethoscope or other appropriate device can help narrow down the sound.

[myhilo]

Grossgary, replied

"overcharging the system will make it scream. if you've converted it, the system requires less R134a than the old stuff. i think it's been said it's like one third? 9 ounces instead of 27? either way, overcharged can cause your symptoms and conversions can cause it. check the pressures."

 

Can you give me an idea of how to check the pressures? I have an A/C tech manual and the gauges ( import, confusing instructions) I believe I originally refilled w/ about 24 oz according so I may be too full, but now I need to use the gauges to judge the charge status, and all I have is book learning which I seem to have messed up.

 

I will endure the squealing and look at the compressor pulley next time.