A/C Compressor Clutch

[bill7]

2003 Vibe AWD

How can I determine if the compressor clutch has gone out? Can the compressor clutch be replaced without changing the compressor in this vehicle?
Thanks for your help.
Bill

[lannvouivre]

Welcome!

Tell us more about your symptoms. Is the A/C blowing cold air? Blower working? A/C compressor just loud?

Anyway, if you think that the A/C clutch is not engaging (not blowing cold air), you can verify it by popping the hood while the car is running and look at the pulleys. With the A/C on, look at the A/C compressor pulley and clutch.

If the disc with the weird triangular thing just in front of the pulley is not spinning, the clutch is engaged. You may already know this, but just in case you don't: the disc with the triangle thing is the clutch. When the A/C is on, current flows though...I think a coil inside of the front of the compressor, creating a magnetic field and pulling the clutch down against the pulley, thus engaging the compressor. If the clutch is not engaging, I recommend first checking the fuse. If it's not the fuse, it could still be something else electronic, which is what happened in my automotive A/C class while we were working on an old Ford F-350 Super Duty. (If you're curious, it turned out to be the fuse as well as the actual switch on the instrument panel).

If the compressor is just loud, well...mine is seems pretty loud to me, but it's actually normal. If it's so loud that you can't even hear music over it, that may be too loud.

Sorry about possibly telling you stuff you already know, it's just exciting to talk about something I've worked on before. Good refresher and stuff.

[joatmon]

First off, welcome to genvibe!

As it turns out, I had just replaced the AC clutch in my 2003 Vibe a few days ago. The procedure is in this thread viewtopic.php?f=28&t=37869" onclick="window.open(this.href);return false; When I saw your question, I added to that thread the method I used to test my clutch to determine if that was the cause of my no AC, seemed better to consolidate it there than to post it here.

[lannvouivre]

Just curious because in my class we didn't cover everything...what makes the clutch go bad? What happens?

[joatmon]

Just curious because in my class we didn't cover everything...what makes the clutch go bad? What happens?

Magnetic coils and windings in motors usually are made of many turns of thin wire. I guess the only thing that would keep it from working would be either a short circuit, keeping the electricity from running through enough of the coil to generate an adequate magnetic field, or a break, an open circuit. That is likely the failure mode, but I have no idea what could convince a clutch coil to develop such a condition. Perhaps repeated hammering. that plate really snaps against the pulley when egaging. Perhaps an inherent flaw, like the world famous toyota reliability that so many of us early 5-speed owners encountered

edit - I have since checked out my clutch coil with an ohmmeter, it is an open circuit, so a wire broke inside somewhere

[bill7]

Thank you for your replies. With the engine running and the AC turned on or off the clutch (triangle) does not spin. It does move freely by hand. Does this indicate that the problem is the clutch? The compressor does come on when the AC switch is turned on inside and the compressor does not make excessive noise. The blower is working but blows warm air only. The system is charged. The fuse is good and I replaced the compressor relay switch so that should be ok. If the clutch is not getting ground is there a not too complicated way to test/repair this?

Thanks.

[joatmon]

With the engine running and the AC turned on or off the clutch (triangle) does not spin.

The compressor does come on when the AC switch is turned on inside

These two statements are contradictory.

When the engine is running and the AC is off, the plate (triangle) does not move but the compressor belt pulley moves with the engine driven belt. When the AC is turned on, the coil in the clutch generates a magnetic field, pulling the plate against the pulley, and plate spins with the pulley. The plate is tied to the compressor shaft. If the plate does not move, the compressor is not "turned on."

There is no easy way to test that the clutch coil is getting ground. It is metal, and is clamped to the metal of the compressor housing, which is bolted to the metal of the engine block, which is connected to the negative battery terminal. It may be possible that corrosion between the coil and the compressor or the compressor and the engine block might interrupt the ground, but I doubt it. To check for such a thing, you pretty much have to take it apart as if you were going to change the clutch. If you're going that far into the clutch replacement procedure, you might as well just replace it. But the electrical circuit up river from the clutch relay involves sensors and the car's computer, with the relay/fuse/clutch good, there could be other issues keeping the computer from deciding to energize the clutch.

Did you try the clutch test procedure I posted in the other thread?

[bill7]

I misspoke about the compressor being "on". Now I understand that the compressor can not be on unless the clutch is engaged. I assumed the compressor was coming on when I pressed the inside AC switch on and the engine RPM would noticeably change.

I can feel a thump from inside the compressor relay switch when turning on the AC button so am assuming I have power at that point. Will try your test procedure number 5 and see what I get.

Thanks again.

[bill7]

I need to have my ac clutch replaced on a 2003 Vibe and this is what a mechanic said about replacing only the AC clutch and not the compressor:

"I do not do just clutch replacement. That was a normal practice in the past but with the newer cars it does not work well. It is possible to replace just the clutch but the repairs usually leak shortly after so the normal practice is to replace the compressor now."

Has anyone else heard of this?
Thanks.

[trb]

I think he wants to line his pockets with more money. And besides, the clutch has nothing to do with the AC leaking, if he does his job correctly. He should not touch the refrigerant lines at all. I'll bet he's thinking it would be easier to evacuate the system, replace the whole compressor, charge it back up and charge you probably $400 more for it. I've replaced the AC clutch twice on my Mustang, (in ~20 years) and did it on two other vehicles also.

Actually, I just looked on Advance Auto and Autozone, and they don't sell just the clutch. That might be why. A clutch looks to be less than $100 from online parts places like RockAuto. A new compressor is about $400 or so.

[joecoolinatl]

I've got to change out the compressor clutch as well, at least I believe it's the clutch and not the compressor. 03 Vibe Base /Auto
just broke 118k, AC always worked like a charm, until 2 weeks ago, it was working the past month before that w/o a prob and one day I get in and while driving turn on the fan, hit the AC switch and nothing. sounded like the compressor wasn't coming on, so when I got home, popped the hood, turned the ac switch on, the clutch is not clacking or spinning.
When the car isn't on, I can spin the clutch plate. I thought maybe there was a chance that it had a leak and was low on R134A, but the gauge showed it in the red. I'm assuming this is because the compressor wasn't kicking on due to the clutch, and the low pressure line was not cold at all.

Friday I'm going to grab the voltmeter and pull the relay under the hood in the fuse block to make sure it's getting 12V from the fuse.
hopefully it's just the compressor clutch. I've got a 3600 mile drive coming up in august lol. don't want to make that w/o AC