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Gary
Gary, ASE Certified Technician
Category: Nissan
Satisfied Customers: 834
Experience:  Senior Technician
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Compressor clutch does not engage. using a test light, no

Customer Question

compressor clutch does not engage. using a test light, no power is getting to the clutch. My problem is when I run a hot wire from the battery to the compressor clutch, it still doesn't engage.
Submitted: 8 months ago.
Category: Nissan
Expert:  Gary replied 8 months ago.

Hi there,

The most common reason for no compressor clutch is low system pressure, low gas.

Can you get the system pressure checked?

The high/low pressure switch has disabled the compressor.

Gary

Customer: replied 8 months ago.
I understand that the pressure switch disables the compressor. The system does have freon. Like I explained on my first comment, I also tried by-passing the pressure switch. yet the clutch will still not engage. That is what I'm having trouble understanding. I have repaired plenty A.C. systems but this one has me stumped. I know that if I by-pass the pressure switch and the clutch kicks in allowing the compressor to work and the A.C. to blow cold I have a bad pressure switch. There is know power going to the clutch and even running power direct to the clutch, it still won't engage.
Expert:  Gary replied 8 months ago.

Ok, I'm glad we are on the same level.

It seems the compressor is permanently grounded one side, and 12v switched, unlike most that are ground switched.

Can you measure the clutch coil resistance, must be open circuit.

Gary

Customer: replied 8 months ago.
I'm assuming the clutch coil is fried. but would that some how keep power from going to the clutch ? There is a ground wire and a positive wire coming from the clutch. I have directly grounded the ground wire and ran the positive wire directly to the positive post on the battery. The clutch doesn't budge. I hate to replace the clutch and that not be the problem. What's your professional opinion ?
Expert:  Gary replied 8 months ago.

Hi again,

The clutch is open or short circuit if it won't engage when you supply 12v and ground.

If there is any form of spark as you make the last connection, there is a "circuit" but if the windings are partial short circuit, then it doesn't create enough electromagnetism to operate the clutch.

If there is no spark at all, the coil must be open circuit.

I have seen compressors overheat and burnt out the clutch coil.

So before you replace the clutch coil, ensure the compressor is not seizing by turning it by hand to feel it's operation.

I'd say the clutch coil has gone partial short and blown a fuse or relay contact.

Gary

Expert:  Gary replied 8 months ago.

Hi again,

I hope my advice has been of assistance to you.

Kind regards

Gary

Expert:  Gary replied 8 months ago.

Hi Domingo,

How have you gone with your A/C problem?

I hope my advice has been of assistance to you.

Kind regards

Gary