$25 AC fix

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$25 AC fix

Postby Rob_O » Tue Aug 13, 2019 6:02 pm

The AC in my '92 was not working, it got hot again so I decided to fix it. I tested everything along the way to see if there were other problems I needed to fix. The AC compressor in the 90-93 trucks is controlled by ground you will need to do a little more wiring if you have an <90 truck. This procedure should work for both diesel and gassers

Tools:
* Continuity tester (old school with a bulb)
* Strippers and crimpers

Parts:
Four seasons 35720 cycling switch
Red butt connector
Red female spade terminals (2)
Crimp cap

Procedure:
* Locate the three wire connector for the electronic cycling switch. The connector should be between the washer fluid tank and the fender and the switch is right where the lines go into the cab. Verify the blue/white wire has ground when the switch is in AC mode and open in off mode, if it doesn't you may have other stuff to fix
* Find the AC relay it's the rearmost relay on the drivers side inner fender. Use your old school test light to probe the skinny Blue/Orange wire, with the ignition on the relay should trip and you should hear the AC clutch engage. Start the truck the AC should blow cold, if it it doesn't you may have other stuff to fix
* Remove the factory ECC switch, the capillary tube will slide out of the tube brazed into the slide of the suction line. Replace with the mechanical switch
* Remove the split loom from the harness and move the ECC wires back toward the cab. Cut the factory 3-wire connector and put the crimp terminals on the blue/white and brown wires. Connect them to the new switch, crimp cap the blue wire you no longer need it
* Pull the connector from the PCM and verify your wiring. Pin 27 should have ground with the system in AC mode and the test light should trip the AC clutch relay on pin 34. The connector has numbers molded into it
* Remove the back cover from the PCM connector, cut wires 27 and 34 and splice them together with the butt connector.
* Put everything back together, start the truck and you should now have working AC

Disclaimer:
I do not know this is the best pressure switch for our trucks I picked this one for an 1981 truck because it was less expensive than the newer ones
Rob_O
fuel screw!!!!
 
Posts: 79
Joined: Sat Sep 01, 2012 11:03 am
Location: Louisville, KY

Re: $25 AC fix

Postby BC847 » Tue Aug 13, 2019 8:13 pm

NICE! 8)
David

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
BC847
Administrator
 
Posts: 2005
Joined: Wed Jan 03, 2007 5:22 pm

Re: $25 AC fix

Postby Rob_O » Wed Aug 14, 2019 10:16 am

BC847 wrote:NICE! 8)


You're welcome. Took me longer to make the post than it did to make the repairs. I would be honored if you could add it to the sticky links
Rob_O
fuel screw!!!!
 
Posts: 79
Joined: Sat Sep 01, 2012 11:03 am
Location: Louisville, KY
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Re: $25 AC fix

Postby BC847 » Wed Aug 14, 2019 6:29 pm

Done.
David

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
BC847
Administrator
 
Posts: 2005
Joined: Wed Jan 03, 2007 5:22 pm
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