94 Caprice, Electrical(Fuse) Problem

JOHN MAZZELLA

MEMBER
1994 CHEVROLET TRUCK

Need Advice, Chevy Caprice Classic, 1994 with 129500 miles Motor is: 5.7L (350) LT1 Motor.

Complete A/C Overhaul done on 3 July 06 (DIY) but verified and inspected by A/C Tech (A/C system done correctly).

Problem is 3 minutes after A/C runs, it blows the 10amp fuse located underhood which controls Primary Electric Fan, once fuse blows A/C compressor turns off. Compressor Clutch works properly (not dragging) A/C Compressor relay also working properly.

I verified and checked all Cooling fan relays (All fully fuctional) and also checked Primary Fan Motor (to ensure motor is not dragging and drawing to many amps) (Fan Motor is working properly).

Would like some advice on what else I could be looking for. Any help/assitance would be appreciated!

1 Reply

MIKEYBDMAN

MECHANIC
623 POSTS

Ok, if I had to guess, I would say you have a bad clutch.
Here is what is in the circuit one that Primary Fan Fuse 10 amp.
The Powertrain Control Module activates an internal switch to give a ground to your ac compressor relay coil. This allows power to flow from your fuse to the ac compressor clutch. Power does tap off after the relay to give a signal to the powertrain control module, and there is a diode 16mm up stream from the compressor clutch connecttor to prevent electrical spikes.
Lets say the powertrain control module is good, since it was not worked on when this problem started. That leaves the diode, clutch and relay as the problems. I doubt it is a wire problem if it pops at the 3 minute mark each time.
If you didnt accidentally removed the diode when changing the parts, I doubt it is the diode. Usually of they go bad, they stay bad. (Outside chance that it might heat up and fail)
This leaves me staring at the clutch. I know u said it wasnt dragging, but it is electrical, and if it is drawing too much current, it will pop a fuse. Check the plug real good and make sure there is no corrosion adding to the resistance. Also check the engine ground that gives the clutch a ground. If it is loose or corroded, it may cause extra current draw to pop a fuse.
Good luck on fixing this. And if I think of anything else I will post it.