i am having a problem on my 91 chevy camero 3.1 with charging the ac, i have installed a new orfice tube, dryer , ac comp but still having the same problem when charging it starts to do ok, taking charge and suction lines getting cold but part way thru or near end of trying to charge comp begins to cycle and the pressure on the low side of gauge goes way up 135-145p when comp.cycles off when it cycles back on only drops to around 60- 70 p and no longer is cooling. system was converted from r12 to r134 some time back and when we are charging with r 134 we are only putting in 1.8pounds when with r12 it was 2.25 from factory,so i dont believe we are over charging, also car has set for a couple of years and not run prior to putting back on the road and trying to fix ac. any ideas would be appreciated

did you pull vacuum on the system prior to charging it?

yes we did pull a vacum for about an 1/2 hour, thank you for the reply and any help you may be able to offer. i have not had an ac problem like this one

make sure your cooling fan(s) are coming on and the condenser is clean, what is your high side pressure? have you tried bypassing the low pressure switch to keep the system on?

i have not checked the fan, as far as the other items just before installing the replacement parts i mentioned before i cleaned small amount of debre at very lower of cond.and sprayed fins thru with water hose to remove any dirt, my high side of gauge if working correctly is only reading around 60-70p. i have not tried to bypass the low pressure switch as of yet. i am wondering if i could have an internal blockage somehow? before we installed the new parts with orfice tube out and comp. off we blew thru lines , cond. and evap. with comp.air seemed clear, but still wonder if could be blockage somehow. thanks for the help

I would suggest re-checking the orifice tube, even though that means
loss of refrigerant and re-vacuumming.

Case in point: On my son's late model Grand Prix, the compressor began
failing. He continued to operate it until it failed catastrophically. After
replacing the compressor, efforts at re-charging produced the same
symptoms you describe. The (new) orifice tube was completely clogged
with residue from the previous failure. The lesson here is that its cheap
insurance to flush the entire system when re-assembling, prior to
evacuation/re-charge, especially if some type of failure was involved.

It's not clear why you replaced the components, so that's the best
I can offer. Good luck.

it would not be a problem for me to re -check orfice tube again as i drained the freon from the system after the pressure was so high on the suction - low side, but the orfice tube now in it is the 2nd orfice tube because when i first tryed to charge for the very 1st time we had never had anything apart just tried to pull vac. & install freon, after the problem already mentioned (very high pressure on low side & loss of cooling )we pulled orfice tube out & changed thinking it would be the problem (it was a little dirty but did not have shavings or chunks of rubber as i have seen some have when a part failed on the system ) we replaced it , then after this did not take care of problem (still same as before) decided to replace ac comp. so we blew out all lines with compressed air and replaced accum. drier and orfice tube again. we have since last post checked and the fan is not working as it should, working on that now, i know fan must work when ac is on but not sure it would cause all the problem i am having, thanks to everyone for response and help it is greatly appreciated.