OK I have a 92 LS and the AC only blows cold SOMETIMES... It has at 2k RPMs 40psi on the low and 160 psi on the high. When its only blowing cool not cold the condincer fans are not turning on but when they turn on its cold... but only on the passenger side center vent the others are just cool...

 

One possibility is that it's not releasing enough heat out of the condenser. Check to see if there are lots of leaves or debris in between your radiator and condenser. Also, spray down the condenser with a hose to clean it up and see if your performance improves.

 

didnt help.

 

I like to see about 250 on the high side and in the 40's on low when the evap is warm. High interior fan and 250/40 should be cold across the vents. Sounds like its low on freon to me. R12 still? Convert it!

 

Its been converted already. When the fans DONT kick on and its sitting at idle the numbers are 52/260. at 2k rpms its 44/180

 

When the RPM's are up, the engine driven fan is pulling enough air across the condenser to keep the head pressure down. Disconnect the temp sensor connector at the bottom of the radiator. That will force the fans on high. Solve the fan issue before you proceed. Still sounds low on freon.

 

low freon....thats why u have low pressure. is the compressor clutch
engaging/disengaging a lot?

 

Nope it stays engaged all the time unless I put it to the floor.

 

its not supposed to do that either