Q: a/c kit install on 1990 GMC 2500 Pickup

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flushed the system, replace orifice tub, added 3 oz Pag 100 oil to new compressor, put the rest of the 8oz in accumulator, vacumed for 45 minutes. Added 1 can of r134a, compressor began cycling with short clutch runs. Low side pressure increased to 100, high side never got above 50. Removed coolant, 1 oz oil sample is black. What did I do wrong?
(1) Answer
(6) Comments
System still has debris in it if oil is contaminated. Did the original compressor grenade internally?
no, it was a bad clutch coil. the system flush came out clean. But the new compressor would not turn by hand before I installed it. The instructions said that some GM compressors (H-6)/similar will not. I don't know if this one is one of those. Did this new compressor have a problem? It turns now but not freely, which is understandable. I got a feeling... this compressor was bad from the supplier, but I don't want to cast blame before I'm sure of it.
Ok, I figured out what I did wrong. I put the orifice tube in backwards, and it was not restricting the high side pressure. Now I've flushed the system, each component by itself, until everything came out clear. I put some oil based flush in the new compressor, turned it many times and drained it, it came out clear. It is pumping ok. What I am considering... put it back in with 2-3oz Pag100 in the low side of the compressor, 5oz in a fresh new accumulator, put in a new orifice tube, load the system and see what happens. Do you have any input?
Nope........sounds like you've gotten it taken care of. Glad you found the cause of the low side pressure issue. Don't know your skill/diagnosis level so I didn't want to go there if it would've made it worse (read that as more frustrating)for you. .Simple goof.......reply on here to let me know that your freezing your ass off after your done!! Good luck!
I don't understand, the exact same result. Low side at 100, high side 50. Won't take a charge.