ZR-1 Net Registry Forums - View Single Post

mhobtr · 11-11-2018

I have a '91 ZR1 and the wiring diagram in the Electrical Supplement for my AC is on page 8A-67-0.

According to that diagram, the correct fuse is 15A so if a '90 is wired the same as a '91, it's curious that you have a 25A fuse. That might indicate that this is a older problem that was dealt with by installing a larger fuse to eliminate tripping. This is not a good situation.

If you want to eliminate the AC clutch as a potential culprit, pull the wiring connector from the low pressure switch at the accumulator and see if the fuse blows when you turn on the AC. If it does, you need to look elsewhere.

If it doesn't, you need to measure the resistance of the clutch coil with an ohmmeter. I believe the correct resistance is around 7 ohms.

Looking at the wiring diagram, I believe you should be able to check this at the low pressure connector but there is an "AC clutch diode" in that circuit that you will have to deal with. If you read zero or very low ohms, reverse the meter probes and see if the reading increases to approximately 7 ohms.

If it does not, you will have to go to the two wire connector for the clutch which is on the side of the compressor (unfortunately under the plenum).

The AC clutch diode is taped inside the wiring harness, under the plenum, right before the clutch wiring connector. If you separate the connector, you can then measure the true resistance of the coil without the diode in the circuit. If the clutch circuit reads good, you will then need to check to see if the diode is OK. If it is, it will read zero ohms one way and open circuit the other way.

11-11-2018	#9
mhobtr Join Date: Apr 2016 Location: Birmingham, Alabama Posts: 60	Re: HVAC keeps blowing fuse I have a '91 ZR1 and the wiring diagram in the Electrical Supplement for my AC is on page 8A-67-0. According to that diagram, the correct fuse is 15A so if a '90 is wired the same as a '91, it's curious that you have a 25A fuse. That might indicate that this is a older problem that was dealt with by installing a larger fuse to eliminate tripping. This is not a good situation. If you want to eliminate the AC clutch as a potential culprit, pull the wiring connector from the low pressure switch at the accumulator and see if the fuse blows when you turn on the AC. If it does, you need to look elsewhere. If it doesn't, you need to measure the resistance of the clutch coil with an ohmmeter. I believe the correct resistance is around 7 ohms. Looking at the wiring diagram, I believe you should be able to check this at the low pressure connector but there is an "AC clutch diode" in that circuit that you will have to deal with. If you read zero or very low ohms, reverse the meter probes and see if the reading increases to approximately 7 ohms. If it does not, you will have to go to the two wire connector for the clutch which is on the side of the compressor (unfortunately under the plenum). The AC clutch diode is taped inside the wiring harness, under the plenum, right before the clutch wiring connector. If you separate the connector, you can then measure the true resistance of the coil without the diode in the circuit. If the clutch circuit reads good, you will then need to check to see if the diode is OK. If it is, it will read zero ohms one way and open circuit the other way.