Where did you add the other "ground" wire? And, more importantly, why?
The compressor should only have two wires, the green and black, as you stated it had. The green wire is power from the A/C switch, and the black wire is grounded to the compressor bracket. The early cars, like yours, should also have a thermal limit device in-line on the ground side. It doesn't have to have it, but it saved the compressor in case of an overheat condition. What it would do is act as a fuse. If the wire for the compressor got too hot, the limit would open, and kill power to the compressor. Too much heat could be from a short in the elector-magnet that engages the compressor clutch, or even from the compressor not cycling on/off as it should.
You may well have a compressor clutch that is malfunctioning/drawing too many amps, causing the problem.
What Ken suggested, as far as removing the belt, was to see if the compressor was causing fluctuations in the crankshaft rotation, which could cause the timing to jump around, if the timing chain/gears had some wear/slack. The same could be said if the bearing for the compressor pulley was too tight, or failing, but they normally make a noticeable noise when that happens.
Also, with the belt off, and the compressor plugged in, it would tell if there was an electrical issue with the compressor, or a mechanical one. With the belt off, and the A/C on, if there is no engine miss, then problem would be compressor related. If the miss still exists with the belt off, it is an electrical issue.
I hope some of this helps!
btw...the compressor should
not run in any position except "A/C, or "Defrost". If is does, then that is another electrical problem we'll have to figure out.
Adams' Apple2007-12-01 09:00:52______________
Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"