AC has plenty in it but wont work?

I have a 1991 RS 5sp coupe

My AC stopped working, I thought it needed to be recharged so i took it to the shop, He hooked it up and said it had plenty of charge left and the pressure was really high in the system for some reason. He said this is causing it not turn on. I didnt get much past that since it was just an oversight while he was doing something else for the car.

So what can i do about having to much pressure and it making the compressor not kick on?
Summer is around the corner and i really want the AC to work lol

oh yea, i have some R12 (bought it before i knew i was all ready retrofit)
does anyone need it? I dont wanna throw it out

would it not be the high pressure switch?

i dont follow

I mean, i don’t what you mean by that. When he was hooked up and charging it he said the pressure was way to high, and it was probably preventing the condenser from turning on.

Any Ideas?

He was saying that the pressure switch preventing the compressor from engaging is a normal consequence of high refrigerant pressure.

The pressure may be higher than normal due to a flow restriction somewhere in the system, or it may have been overcharged when the R134a conversion was done.

Or, the problem may be something else entirely and the mechanic was simply speculating that the pressure was too high.

well he was reading the guage when recharging it and said it was somewhere in the 50-55lbs neighborhood, he said that was a high amount so it I’m sure it has high pressure but i just dont know how to fix it so my AC works again

55 psi? on the suction port for 134a thats a good reading. if its on the dicharge(from the compressor) thats way low. on a warm day, meaning between 70-80 degrees outside, low side should be between 40-50psi and 125-150 on the high side. its hard to say exactly cuz the properties of refrigerant and the way A/C systems are designed.

back to your 50-55 lbs comment, our system(according to the owners manual, not a service manual) only holds 32oz of refrigerant, so 55 lbs would be WAY over charged. i work on transit buses(yes in san diego where my foreman and a fellow mechanic were murdered by one of their own) and they only hold 17 lbs. also thats where im getting most of the stuff i just said, but i have taken regieration classes and am going to be getting EPA certified in about a month or two.

So what do i do? I just dont want my mechanic to try and sell me a new system if i dont need it ya know

i would suggest evacuating the system and give it a proper recharge from a known good shop

Is that what i tell the guy when i go? “Evacuate and recharge?”

how much does this usually run, some shops around me inflate prices this time of year (Shoobies) and i dont wanna get taken for a ride

ya just tell them that. it would be best if you have them charge it with nitrogen to a) check for leaks while not venting refrigeration and b) to help dry out the system had it been contaminated and not properly taken care of before but money is king and just an evacuation and recharge should be good.

as far as pricing i have no idea how much is normal, ive never had to get mine recharged and at work we just maintain the fleet so we buy in bulk not individual, sorry


yeah, i’m also studying for my EPA certification and you’d probably be best doing what he mentioned previously, having the old refrigerant recovered, than having the shop pressure check it with a nitrogen charge, than evacuate and recharge. I just did the same thing on my 91 gs i recently bought and it works great now. If thats not the issue you have some sort of restriction causing a high head pressure in your system. I dunno about automotive, but a dirty or plugged condenser coil can cause high head pressure on the commercial units i work on.