A Fix for Corvair Air Conditioning and Poor Acceleration.
By Bob Gill
North Texas Corvair Association
My í65 Monza coupe is equipped with a 110 HP engine, a powerglide transmission and factory installed air conditioning. I was driving out of a parking lot on a rather hot day in March when I decided to turn on the A/C. I waited for traffic to open up so I could get on the highway and at the first halfway decent opportunity I floored the gas pedal and turned onto the road. It really wasnít a dangerous entry but my acceleration was dismal.
I recalled that during the summer that my Corvair lacked power with the A/C on but I just put up with it rather then swelter in the sultry Texas heat. This time was a bit different though because Iíd been driving around most of the winter without A/C and my lack of acceleration really stood out.
Then it dawned on me. Every vehicle Iíve owned with A/C since 1984 had a control that would open the circuit to the compressor clutch under hard acceleration thereby taking the extra load off the engine by stopping the compressor. I wondered why the engineers that developed A/C for the Corvair hadnít included a circuit for that, at least in my í65.
I searched through Google and my Corvair A/C book to see if this concern was referenced anywhere but I didnít find anything at all. An eBay search resulted in one sale of a NOS vacuum operated switch for a í63 Cadillac the looked like it might do the trick but upon asking the seller if the switch was normally open or closed. He replied that he had no idea. Plan B went into effect. I decided that I could accomplish about the same thing with a micro switch.
I mounted a micro switch to a bracket that I made that connects to the vacuum ďkickerĒ that advances the throttle when the compressor clutch is energized. Whenever the throttle is fully open the micro switch opens the circuit to the compressor clutch though a relay and the compressor stops. A second adapter to the throttle shaft makes it completely adjustable so as to activate the switch at the proper throttle position.
At this writing Iíve only been able to test its operation once and the weather really wasnít very hot but the results are very encouraging. I can get away from stop lights just as fast as ever now and I donít even notice that the A/C isnít running for the short time itís off. I'm willing to bet that it'll be just fine in the hot weather though.
An update: Since this article was written, I've hooked the microswitch to a vacuum diaphram device. (Actually it's a converted distributor vacuum advance.) A screw in the end of the shaft that physically closed the microswitch makes the point where the switch is adjustable so that the compress will kick in at a predetermined level of vacuum. This really works great especially since I've retrofitted the old GM A6 compressor with a more efficient Nippon Denso compressor. You can find details of that article here
Iíve kept this article brief for many reasons but if you should have any questions about this please feel free to email me at firstname.lastname@example.org.