Model: G20 Conversion
Engine Size: 350
Refrigerant Type: R134
Ambient Temp: 90-100
Pressure Low: 70
Pressure High: Unk
Country of Origin: United States
This is a conversion van with dual A/C units, 110,000 miles on the vehicle. Until this spring, the A/C has worked flawlessly.
In April, it stopped cooling even though it was holding a charge. I replaced the orifice tube, and it was dirty but not alarmingly plugged. I recharged the system and it worked fine until about a week ago. It has also been 90-110 degrees here in NC for about a month, so the A/C system has been taxed more than I would assume it ever has before.
I checked the low side (with a cheap recharge can gage) and it was 70psi. I took it apart and this time the orifice tube was not just plugged, it has a thick shell of metal shavings mixed with grease/oil absolutely coating the entire tube. Replaced tube again and now as I'm recharging, the compressor is making a slight groaning/grinding noise. It's barely noticeable above the normal engine noise, but it is distinctly coming from the compressor and it isn't the normal operating noise.
So I have 2 questions:
1) Where are the shavings coming from? I am a novice at A/C repair so I am assuming the compressor is the most likely place that could generate shavings, but is there anything else in the system that could be damaged?
2) Even if I put a new compressor on it, how do I get all these shavings out of the system? As badly as the orifice tube is coated, there must be significantly more shavings throughout the system that haven't made their way to the catch tube yet?
I don't have a good gage set or vacuum pump, and am assuming those will be required purchases if I have to replace the compressor. I do all of my own auto repairs so I would want something I could use in years to come, but I'm just a DIY'er with a couple of old GM cars so it doesn't have to be anything industrial quality. Any suggestions would be great.
You have the dreaded suction reed valve problem- your pumping is going south real quick- the material is stainless steel reed material- (non-ferrous- magnet won't attract)- you can do what I do- install new OT and then run it for 30 minutes and then reclaim refrigerant and install another new OT. Shavings won't go by the OT- and if they do- then install a screen (from V-5 service compressors) into HD-6 new compressor to guarentee no shavings make it back into the new compressor you'll need..
Old compressor probably turns really easy- with one finger- and has little "catches" as you rotate it- this is a prime indicator of the reed implosion..
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Edited: Sun July 29, 2012 at 7:44 PM by GM Tech
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