Question about 1990 Chevrolet K1500
Problem is in the a/c circuit. Any time the defrost is on the a/c compressor will cycle on & off as it is used to dehumidify the air directed to the windshield. That's why the fuse can blow even in defrost mode.
Unplug the power connector at the a/c compressor and see if the fuse still blows. If not, then with a dmm or vom test a/c clutch winding for short. If ok, then test clutch diode for short. The diode is usually mounted at the clutch winding, but I've seen Chevy's with a diode that plugs into fuse/relay block under the hood. I have replaced these so don't overlook it.
If fuse blows with compressor unplugged then first check circuit between compressor and a/c relay (power side) for a short. It's possible for the wire to rub a bare spot in the insulation along it's travel along the block, bracket or manifold to the compressor. If ok, then test from relay (winding side) back to switch.
Posted on Jun 24, 2009
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Posted on Jan 02, 2017
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