AC fuse keeps blowing.

[Farmer Rob]

So, I keep having the problem of the 10 amp fuse blowing in the under hood fuse block. I have done a good bit to rule out possible causes along with preventive maintenance.

Here is a list of what I have done:

1) Replaced/checked/rechecked all fuses having to do with the ECM,BCM and AC.
2) Checked my relays, all of them, to insure the right amount of current is making it through and that they are properly installed.
2) Printed off the AC wiring diagram for our year/make/model. Checked wiring for a bare wire, from the fuse block, under the fuse block, down across the bottom of the engine over to the compressor with nothing found. Yes, I did remove/replace the wire loom after inspection.
3) Checked the connectors for the compressor as well with no damage or loose poles found.
4) Replaced the parts on the front of the compressor with all brand new parts. New pulley, clutch and coil.
5) Replaced the Low Pressure Switch
6) Captured refrigerant, replaced the orifice tube with a new AC Delco part specified for our vehicle, pulled a vacuum and recharged refrigerant to proper pressure/amount per the reference.
- After all of this, we had ice cold air for a couple of days in our only family vehicle for our family of 6.

***Now, it’s blowing the 10 amp fuse in the fuse block again.

I rechecked the ac wiring diagram and have found an inline diode built into the plug connector of the fuse block side, not the compressor side, of the plug connector that runs control/power to the compressor.

Has anyone else had this problem? If so, is there a part number for the diode/fuse block side of this plug? I have found several on fleabay that look exactly like what I have but do not cover the year/model. Help is greatly needed. Semper Fi!


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[clandr1]

Not sure this will help, but when I had this issue last year, it turned out that a mechanic who replaced my power steering pump had pinched a wire loom when he reinstalled the pump, and over time it rubbed a wire raw which was grounding out on the steering pump bracket/shield. I had to cover the wire up, then the fuse stopped blowing after that. But, sounds like you've already chased the potential wire issue...

 

[PNWYukon]

How often will it blow the fuse? Is it under load, idling, A/C off or on? Only while turning the wheel etc..?

 

[Farmer Rob]

How often will it blow the fuse? Is it under load, idling, A/C off or on? Only while turning the wheel etc..?

The 10 amp fuse blows as soon as both poles from the fuse touch the fuse block. AC is off, no load and it is idling.


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[Farmer Rob]

Not sure this will help, but when I had this issue last year, it turned out that a mechanic who replaced my power steering pump had pinched a wire loom when he reinstalled the pump, and over time it rubbed a wire raw which was grounding out on the steering pump bracket/shield. I had to cover the wire up, then the fuse stopped blowing after that. But, sounds like you've already chased the potential wire issue...

I will recheck the wires today and hope that I missed a bare wire. I will look specifically where you spoke about as well.


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[PNWYukon]

Is that the only fuse blowing. Any other electrical issues? If not, then it has to be a short on that circuit. You have to meticulously check the whole line. Anywhere a harness might have the chance of rubbing, binding, pinching has to be checked, even if you have to peel back the tape or sleeve.

Another suggestion: Unplug all the actuators, put in new fuse. Does it blow? If not then plug them in one at a time to determine which one might be the culprit.

Another suggestion: Blower motor resistor might be fried or dying. Remove and inspect for melted wires etc.