Ok.. I have a 91 rs 305 TBI. Completely stock. When I switch on my a/c with the car running, the idle falls drastically to 4-500 rpm. Also, when the a/c is on and im idling, it jumps around randomly. While driving it bogs around in low rpms. It is a brand new compressor, seals, and refilled with R134-a. The a/c works excellent. The compressor doesn't shut on and off while these problems are occuring, i double checked. Could a vaccuum leak in the HVAC cause all these symptoms? because i hear a slight hiss sometimes in my hvac...

Any ideas or help appriciated...

 

Is this a stupid question or something.... anyone know?

 

Check to see if your compressor clutch is engaging and disengaging. Lo refrigerant pressures can be one reason for rough idle. Also, what is your idle speed with A/C off? I'm usually at 500.

 

My idle is at 500 without a/c on. The clutch comes on, and stays on, i watched it. Also i think my idle goes to 900-1000 witht the a/c on, but when i start letting the clutch out it starts to die and bog down no matter how high i rev it. It's done this since i got my a/c fixed, before the a/c never worked.