Bad new OEM magnet clutch? (1 Viewer)

[truthdetector]

Got the A/C charged a couple of weeks ago and the compressor fired right up - A/C worked great.

The next day, I tried to run the A/C and it didn't seem to be cold, so I opened the hood and sure enough the clutch wasn't spinning.

First, I used a DIY A/C recharge can to confirm there was still pressure in the system.

Then, I got smart and just tested for voltage at the lead to signal to clutch to engage. There is voltage, which rules out low pressure, bad pressure switch, etc.

With voltage at the clutch and the clutch not engaging, I figured my shims made the clutch go out of spec after the first run, so I removed the clutch and removed one shim. It resulted in it being a little too tight, but I figure the clutch will adjust itself by wearing away the .5 mm of being too close.

Nope. STILL, the clutch won't engage. With +12V and a solid ground on the brand new compressor and clutch assembly, is it really possible that the magnet clutch assembly died after one good run?

I can't think of anything else to check besides doing a parts-cannon new clutch assembly.

Any ideas?

 

[DivByZero]

Unplug the clutch, and measure ohms across the magnet. Should be one pin in, put a lead on that, and the other on your battery negative, or any other clean ground connection. If the magnet itself is open circuit (IE, busted), you'll get no continuity/basically infinite resistance. If you get almost no resistance, there are only two possibilities - the magnet is working, or there's a short circuit to ground bypassing the magnet.

 

[truthdetector]

Unplug the clutch, and measure ohms across the magnet. Should be one pin in, put a lead on that, and the other on your battery negative, or any other clean ground connection. If the magnet itself is open circuit (IE, busted), you'll get no continuity/basically infinite resistance. If you get almost no resistance, there are only two possibilities - the magnet is working, or there's a short circuit to ground bypassing the magnet.

Thanks for the idea.

I measured 3.3 Ohms from the pin to the compressor housing where the ground screw attaches.

 

[DivByZero]

Right, so you're in the second part. Power is either flowing through the coil, indicating your problem is mechanical in nature (ie, the plate isn't sliding even when the magnet is active), or power is going straight to ground before entering the coil. You need to look closer. I'd start by inspecting that wire and making sure it's properly isolated from ground. Might be easiest to pull the clutch again, and inspect/test the magnet on the bench at this point. Pay very close attention to the electrical connection in, and look for any places where power could find its way to ground.

 

[Rusty Marlin]

You can also trigger the magnet manually with a set of jumpers. I connect the hot side and tap the ground side, the cluch will clunk into engagment if the maganet coil is good. I'm pretty sure you can buy just the coil as a replacment part if needed. I know you can on other vehicals I've worked on, anyway.

 

[alia176]

Agree with Rusty, above. Simply apply +12vdc to the single wire coming out of the clutch coil to see if it goes CLICK. If that works, then the issue is upstream, meaning the clutch coil isn't being told to engage. Which usually points to the Trinary switch by the battery.

Given the fact that your A/C isn't as cold on the second day after refilling, this makes me think there's a slow leak somewhere. The best thing to do is purchase an A/C manifold gauge from Harbor Freight and do some investigating.

 

[White Stripe]

Does the clutch have a good ground?

 

[truthdetector]

Hi all.

I've already confirmed voltage is being sent, which rules out anything upstream.

Yes, it has a good ground - it grounds to the compressor housing and all of it is brand new.

Before I order a replacement clutch assembly, I will find some leads and try to get it to engage (click). I did that test on the bench before installing everything and it obviously worked fine once. I'm starting to think it just crapped out for some reason. Maybe the T dealership will take it back? Is there a warranty on something like that?