AC doesn't engage, replace just clutch or...

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AC doesn't engage, replace just clutch or...

Postby Erichimedes » Mon Sep 18, 2023 7:43 am

Hi all,
New 2012 owner here, I'm going through our new truck and doing all the basic service stuff to make sure it's up to date. We bought it with the AC not working, and it's time to dive into that.

Here's what I know:
-The clutch DOES receive a 14v signal when the AC is turned on, but it does not engage.
-According to the gauge on my cheap AC recharging can, the system is way over pressure. Guessing the previous owner tried to charge it up in an attempt to get it working.
-Compressor is a VALEO brand, which is supposedly an OEM approved part?
-I'm told by the sellers of an AC compressor clutch kit on ebay that their kit is indeed compatible with my compressor.

A friend of mine is an HVAC guy, so he can help me get the system down to the correct operating pressure and reclaim some of what's in there. Same is true if I need to get it all out and replace the compressor.

So I'm trying to weigh out the probability that it's just the clutch. The clutch is a $50 part, and the compressor is a $275 part, and more work to replace. So is it worth taking the chance and trying the clutch first?

Have you replaced the AC clutch in your car? Did it fix the problem, and/or how long did the repair last before just needing to replace the whole compressor?


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Re: AC doesn't engage, replace just clutch or...

Postby VStar650CL » Mon Sep 18, 2023 12:12 pm

Valeo is one of Nissan's standard vendors for compressors and alternators, but I don't know if it's OE for an R51. The question is, did the clutch die because the compressor locked up and trashed it, or is it just a bad clutch? Ohm through the clutch to ground, most of them draw a couple amps and will typically ohm at 5 or higher. If it's open circuit then it's likely the coil died and you can just replace the clutch. If it reads normally then the clutch probably has a mechanical issue, which in turn usually means a bad compressor.

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