High pressure A/C switch on a 92?

BILL MAYNOR

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BTW, installed a larger condenser coil up front from Vintage Air to work better w new AC coolant. Measured air coming out of center vents at 30deg.

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Queso Del Rio

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I just completed total AC rebuild on 88 K1500. The two wire pigtail ties into the pressure switch on the back of the R4. I grounded the unused 2nd end of the pigtail, which now allows the recirculate/max air door to operate for the first time in decades. The pressure switch wire breaks out from the larger harness that runs around the front of the block, not back towards the passengers side.

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Yep, my 89's (aka Half-Sucked Atomic Fireball) original A/C compressor finally gave up the ghost after having to buy R-12 in Mexico (when you still could) and the eventual conversion to R-134 years ago. She's been great since I bought her brand new off the lot! Gonna replace everything and the 2-wire switch is the only one I could find. Here's a couple of pix of the compressor and a diagram (gray wire's black colored in the schematic) from the original 1989's 1373 pg. repair manual.

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PlayingWithTBI

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Guys, the old design with the 1 wire high pressure switch only closes the "air inlet" door, it does not shut off the compressor!!! That switch is NLA and is pretty much useless. We're now running R134A which is not as efficient as R12 so, it'll run at higher pressures. If you don't protect your system with a high pressure shutoff switch, you're leaving yourself open for catastrophic failure. Then, people will say the seals on the R4 pump are "junk and don't hold up" when, in fact, it's running over design pressure!
 
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