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Discussion Starter #1
There is a short somewhere in the AC system of my wifes's cavalier. Fuses blows when you turn on the compressor. The curcuit (fuse) also controls the fan. Turn the fan only on--no blown fuse. Turn the compressor on..fuse blows. Obviously the short is somewhere on the Compressor hot side. How would you go about troubleshooting this gremlin. Thanks rb6667
 

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A schematic always helps. A short is rarely a wire that is touching the frame or chassis. It's usually something that is on the circuit that has gone bad. I start by unplugging things that the fuse powers.
 

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Thanks for the reply John, This fuse apparently only feeds the blower fan and the compressor. The compressor will run all day with the car standing still--no blown fuses. Drive the car, it will blow, sometimes within a day, sometimes almost as soon as you move. I figure it is a loose wire somewhere. I've even given thought to completely re-wiring the compressor, bypassing the existing harness. Any other thoughts? Thanks, rb6667
 

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Yes, but the fused line also goes to a couple of switches and whatever controls fan speed. These days there's a little more circuitry.
Sorry I can't be more exact unless I look at a schematic.
 

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Thanks John, I'll see if I can dig up a diagram and figure out what is going on. This thing is driving my wife nuts---you know what that's like.
 

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Had just about the same problem with my 91 Suburban, high speed blower/compressor clutch kept blowing the fuse.

The circuit also went to the computer to speed up engine idle and really did something weird
When the fuse would blow, the speedometer would quit and the transmission wouldn't shift.

Not supposed to be any connection between the speed sensor and that circuit according to everyone I asked but I cut the green wire to the computer and it quit doing it.

I bought a manual on CD from O'Reilly and finally located the problem which was the wiring harness laying on top of the damper control levers on top of the heater plenum.
 

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Discussion Starter #7
Thanks for the info Dean, I do have some new finding to report. I replaced the 25 amp fuse with a 25 amp circuit breaker, knowing that I could hear it click on and off. I moved wires around under the hood with the AC working--no clicks. My wife tells me when she drives it, if she keeps the blower speed on low, it works--move the fan to med or high--the circuit breaker starts slicking on and off rapidly. Obviously the short is in the fan switch curcuit somewhere. Bad switch, wires going to the switch? Any insight? Thanks, rb6667
 
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