SICMARO

Have an LS1 pcm out of a camaro and running vintage air. My idle drops when the compressor kicks on. most of the time it is ok but sometimes the car wants to stall. Can I connect the clutch wire to the pcm to bump the idle? I'd rather not have to install the camaro pressure sensor.... thanks for any info!!!

vannatta20

iTrader: (4)

One trick is to wire up a purge valve. Hook the turn on power 12 volts from the compressor to the purge valve. Once the valve opens up it allows a vacuum leak to occur which will raise the idle.

hookemdevils22

iTrader: (12)

For early truck ECUs, red connector pin 55 (pressure signal) should be grounded and pin 17 connected to the compressor signal. Source. For the LS1, it appears that you would need to ground red 14 and connect red 17 to the compressor clutch.

SICMARO

So you dont think I need to integrate the LS1 pressure switch?

lt4malibu

iTrader: (39)

I'd have to look but I believe the pcm would need to see the pressure in the correct parameters to command the compressor on. I a write up on here a while back about integrating the older ac system utilizing the fbody ecm to control the compressor

04Z06vette

there is another post on here from the last few days entitled 10mm pressure port or something like that. in it, another user '69 Ghost' responded "If you are looking to control your vintage air system which means a FIXED compressor you want to keep the system you have and program the PCM to accept a fixed compressor type. The sensor is for a variable system that is not made to cycle. This info has been repeated over and over again. GM used different types of compressors on different types of vehicles. All types work. The difference is fixed compressors use a pressure switch that turns the compressor on and off. The pressure sensor is used when the compressor (variable) does not cycle. It controls the fan speeds. Both types will bump the idle and set the fans when programmed properly."

So before you try to hook up any oem pressure switch to a vintage air system, you need to find out whether that switch was for a fixed or variable compressor type.