A/C gurus please help

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creekrat

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So attached is a 94 a/c circuit wiring diagram. The only portions i am worried about is the compressor circuit. So the blue dashed wire (may not be blue in the truck but is depicted as so in the drawing) goes from the panel to the clutch request relay so that when you turn the system on at the panel it pulls the coil voltage and sends the signal through the high pressure and low pressure switches and to the clutch which makes your cold in the cab so long as the high and low pressure requirements of the system have been met...lol. I would guess that the high and low pressure switches are wired to relays that the signal would pass through so as to keep from burning up switches. So what is the configuration of the high and low pressure switches? Both normally open, both normally closed, one open and one closed?

Reason for all this is I did a 5.3 conversion in a 93 rcsb and the stock 93 underhood harness was toast so it got canned. I am looking at using a r-4 compressor or a sanden 508 setup and I am wanting to completely bypass the LS pcm with my a/c. There has to be a way to do this. It would basically be similar to a vintage air and such but using my stock 93 in dash ac panel
 

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SAATR

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Los pressure switch is normally open, high pressure is normally closed. Low pressure closes above a minimum value, high pressure opens above a maximum value. I think the ECM return will disable the system if it sees excessive switching, but don't quote me on that as I haven't worked on one of these systems in years.

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