a/c kit install on 1990 GMC 2500 Pickup

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?

by in Riverside, CA on May 27, 2013
1 answer 6 comments
ANSWER by on May 27, 2013
System still has debris in it if oil is contaminated. Did the original compressor grenade internally?
COMMENT by on May 28, 2013
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.
COMMENT by on May 28, 2013
Might be to your advantage , to bring it to a pro at this point.
COMMENT by on May 28, 2013
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?
COMMENT by on May 30, 2013
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!
COMMENT by on June 01, 2013
I don't understand, the exact same result. Low side at 100, high side 50. Won't take a charge.
COMMENT by on June 06, 2013
Still has restriction.