Engine Size: 5.3
Refrigerant Type: R134A
Ambient Temp: 80
Pressure Low: 28
Pressure High: 225
Country of Origin: United States
Old unit clutch had 12v but wouldn't lock up;no clutch available. So I Replaced a compressor and clutch assembly, accumulator and orifice tube on this truck. Compressor had 6.8 oz of oil in it so I added 1.2 oz for a total of 8oz.
Everything went fine with the evacuation.(30 min and held fine) charged it back up and I think i put a little much in it. it called for 1.8 lbs(28.8 oz.); I put in approx 33 oz best i can tell by shaking the can.
Cools great pressures are L 28 H 225. Clutch will not disengage or at least for about 15-20 min it wouldn't. also the accumulator started frosting up.
would this be the extra refrigerant or something else? thanks for any input...
Clutch will disengage at 21-22 psi, what was your pressure? At 80 degf ambient and at idle, one would not expect a disengagement. Does it disengage when commanded off at the dash control head? Try running it on low fan recirc after 15 minutes of high fan recirc (with windows closed) and see what happens. Chances are good that you have no issues other than too much oil now and a bit overcharged. A little frost is not uncommon under high humidity conditions.
You could have fixed the old compressor for zero dollars by removing a shim- extremely common failure mode on these compressors/vehicles. The air gap was probably too wide- do a forum search for wide air gap.
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......
What would cause the compressor not to cut off when the dash button is pressed?
Edited: Sat July 18, 2015 at 5:07 AM by echeeves
Found out when on recirc, the comp stays engaged to prevent window fog up.
UPDATE...Comp locked up after a few days. it was from advance and was made in china. it was late in the afternoon and my brother has a long drive back and forth to work and wanted to try to fix it asap. We wanted a better part from NAPA but they were closed.
Are these compressors that bad? The only thing I didn't do was flush the system. There was no metal in the O-tube when I replaced it. I will try to find a shop that will flush it for me and then replace the accumulator and orifice tube again.
Sure does pay to get quality parts and do everything you can to make a successful repair. Lessons learned the hard way are not as easily forgotten though!
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