gpbeau Posted June 23, 2014 Share Posted June 23, 2014 New member and new owner of a restored '72. Went to turn on the A/C and found that the clutch wouldn't close. A quick inspection found that the typical two-wire clutch connector on the compressor housing routes to a connector that is clipped to the vapor lines on the LH fenderwell. This connector has three wires: one to the clutch; one to the temp switch on the "suitcase" on the RH side of the firewall; and a black wire to the back of the compressor. (click the links below to open the two pictures) My two questions are 1) what does this three-wire connector plug in to? I cannot find any matching connector from any portion of the harness underhood. 2) what in the world is that black wire connected at the back of the compressor for? With the key off, there is no continuity to ground. With the key on, there is no voltage between that wire and ground. Any help is much appreciated Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted June 23, 2014 Share Posted June 23, 2014 Welcome to the site and I’m sure you’ll find a lot of help here if things come up. The connector you’re referring to is where you connect a thermal limiter. Some people refer to it as a fuse. It’s available at most auto parts stores for a few bucks. You’ll just plug it to the connector and let it lay on the inner fender. The black wire going to the back of the compressor is hooked to the super heat cutout switch. It protects the compressor in high heat situations. Quote Link to comment Share on other sites More sharing options...
gpbeau Posted June 23, 2014 Author Share Posted June 23, 2014 Thanks, Topless72 for the quick response! Curious that the thermal limit switch and the super heat cutout switch don't appear on the wiring diagram. Would be very curious to see a schematic of that cutout switch. Where can a guy get his hands on the limit switch? Quote Link to comment Share on other sites More sharing options...
Leghome Posted June 23, 2014 Share Posted June 23, 2014 I bought my last one at the local NAPA store Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted June 23, 2014 Share Posted June 23, 2014 Here it is. This is from the 1972 GM issued Service Manual page 1A-60. Look at the lower left of the drawing. In the same manual, Pages 1A-53~54 outline the tests and troubleshooting methiods for both the Super heat switch and the thermal limiter. Quote Link to comment Share on other sites More sharing options...
gpbeau Posted June 24, 2014 Author Share Posted June 24, 2014 Perfect! Thanks for that picture. I guess I need to get my hands on the right wiring diagrams. And thanks to Leghome for letting me know where to get the part. Off to NAPA to get a thermal limiter. Thanks! Quote Link to comment Share on other sites More sharing options...
Leghome Posted June 24, 2014 Share Posted June 24, 2014 No more expensive it might not hurt to get two and that way you have a spare in case it blows while out on a trip. Quote Link to comment Share on other sites More sharing options...
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