A/C buzzing sporadically...Any ideas?

[tomlcollins]

My A/C is working great temp-wise. It's blows cold at idle or at speed, at any fan setting, etc.
The problem is that I'm getting an extremely annoying and scary ($$) noise sometimes when the clutch engages in the compressor. It only seems to do it once the engine has warmed up. It starts as a dull buzz and eventually gets pretty loud to the point where is is embarrasing sitting at a stop light. Once the compressor disengages it's cycle it stops, of course until the next time the compressor engages. When it gets real bad it a bit of metallic rattle seems to occur as well.
I'm very worried about this for many reasons. The main reason right now is that I CAN NOT STAND noises or rattles that shouldn't exist. My compressor shouldn't sound like this, and it really bothers me although the A/C currently still works. The big reason is that I'm scared my A/C will go...and that is going to cost at least $750 to fix. I simply can't go without A/C, I live in Charleston, SC.

Does ANYONE have any ideas here? I'm assuming that the clutch isn't engaging all the way and slipping, which would be mechanical and I would assume would require a compressor replacement to fix. I've also been told it could be an electrical problem where the magnet isn't working properly.....Is it possible to replace just the clutch?? I've also read a little about reed valves, and wonder if that could be a problem.

If I can't fix I do have an alternative....I've arranged a deal for a new i350 (28k sticker) that would only leave me financing 18K after my trade in (I owe $5400). Only problem is that my payment will skyrocket from $210 to $350 a month. Advice on this is welcome, too. The dealer obviously doesn't know about my a/c issue. A sidenote on my Rodeo, I need new tires, plugs, tranny service, and brakes within the next 10K miles.

[tomlcollins]

OK, hopefully someone will jump in here. In the meantime, here's an update:

My buddy and me are both pretty mechanically inclined and we have decided that the horrible sound I hear is the clutch slipping in the compressor. We're assuming that it is controlled by a magnet, but I don't have a diagram of it or a service manual so I don't know for sure. Can anyone confirm this??

Here's my plan of action if in fact the clutch is magnetic:
1) Replace the belt...it needs it anyways
2) Smack the compressor pretty good with the wooden end of a hammer next time it acts up in an attempt to reseat the contacts inside.
3) Spray the crap out of the compressor with contact cleaner with hopes of reaching the contacts inside....does anyone know a good spot to spray??? I'm planning on doing this with the compressor on the car.

Any help is greatly appreciated here.
Thanks,
Tom C.

[Amopower]

I have the same problem too and hope someone will post a reply. Mine kinda sounds like someone is holding a piece of cardboard on a moving fan. I think it is definitely an AC clutch issue, but I dont know how "bad" the issue is, and if a new clutch is needed or just some maintenance. The weird thing is that once in a while when I turn the AC off, this buzzing continues for maybe 10 more seconds, almost like the clutch didnt "give up" yet when it should have. 90% of the other time, it will shut right off as soon as I turn the AC off.
I'm trying not to run it (AC) right now, just in case it is a bearing issue and dont want to risk anything siezing up when I'm driving it.

[Blue Bowtie]

The clutch is indeed magnetic/electrical. For a typical electric clutch on an A/C compressor, there are no "contacts" since the clutch winding is stationary.



It is possible to replace the clutch alone, without changing the entire compressor. I'm not sure if it's possible to change it on the vehicle in a Rodeo, however.

Any noises you are hearing are more likely an input shaft bearing of the compressor itself or the noise from valves in the compressor. Valve noise can be increased by incorrect refrigerant charge, incorrect oil charge, wear, a failing accumulator, and probably a fistful of other reasons.

Another less likely possibility is that the clutch is slipping. This would occur most frequently if the clutch is exposed to oil or coolant leakage. This can be cleaned away with a spray of electrical component cleaner or hot water.

[tomlcollins]

I replaced my compressor clutch a couple of weeks ago, but it didn't fix my problem. You can do it with it on the truck without much problem. Search for "compressor clutch" and you'll see the thread.

Now I'm just living with the stupid noise until the compressor goes out on me completely, as the A/C is still working. Apparently the compressors on Rodeo's are known to be pieces of crap, at least that was what I was told by several dealers in SC.

If you care to try a clutch before spending 800-1000 bucks on a new compressor, I've got my old one that I will sell you for $50. It's worth a try, and isn't hard to install. Let me know....you can also e-mail me at [email protected]

[rodeo02]

I can't see this as being a slipping a/c clutch. #1 you replaced it already, #2 anytime I've seen an a/c compressor clutch slip, it gets so hot it smokes and burnes itself up. Like BB says, it's more than likely an issue internal to the compressor. IIRC, they are a swash-plate type of 'pump' so it could be any number of internal wear concerns. In any instance, this shouldn't happen on a 2002!

Joel

[Blue Bowtie]

If I'm correct (and that would be rare) the compressor is a Sankyo swash-plate type. Most of the time, they're a pretty decent unit. There is always the possibility of a weak one, however.

A compressor with noisy valves would normally make noise characterized more as a "buzz", while a compressor with a worn ball/piston would make noise more like a "rattle" or "chatter" depending upon RPM.

If you have a gauge/mainfold set, or talk to your mechanic about it, it almost never hurts to drop in a couple more ounces of refrigerant oil just to make sure it is getting everywhere in the system as a good fog. If the valves are a problem, it might just quiet them down. If the balls/pistons are dry, it may help. If the swash plate or balls are already damaged, it probably won't do much good. The good part is that the system should be R134-A, and oil charge is really cheap for it.

[tomlcollins]

Originally Posted by Blue Bowtie

If you have a gauge/mainfold set, or talk to your mechanic about it, it almost never hurts to drop in a couple more ounces of refrigerant oil just to make sure it is getting everywhere in the system as a good fog.

I was thinking along the same lines, Bowtie. By the way, you're a good addition to the forum! Welcome! I actually was VERY close to just trading it in on a new Colorado or i350 but my payments were basically going to double AND of course all any dealer will give me on a trade in is wholesale value ($5400!!!!). Sucks b/c I was actually going to be able to get a crew cab 4x4 for about $100 over invoice, and there were rebates worth about $2500 (my Dad is buddies with the dealer). Oh well.

I'm probably going to take the truck in this week, I have just been trying not to use the A/C in the meantime. It only makes the noise at idle, which is why I considered the clutch first, plus I could do the clutch myself and I was lucky enough to find the part on Ebay considering it is next to impossible to buy just the clutch anymore. Isuzu dealers don't even sell anything but the whole compressor anymore.

Any ideas on where should I buy the compressor from if I need one? The dealer wants $800 so that's out, no way I'm paying that much. I've found some online for around $450 but I'm hesitant about the quality. I was actually thinking about hitting up a salvage yard....
What do y'all think?

[tomlcollins]

For all those wondering what this problem may be...I've been told something I previously expected from my shop - it's the reed valve in the compressor and I need a new compressor to stop the noise. Yippie!

My shop can't seem to find one around anywhere, anyone know where the best (and cheapest) place to get a decent one is? I have a 2002 with the 3.2 L. If I can't find one for too cheap I'm just going to keep driving it. My only worry was that the compressor would lock up eventually and I would get stuck somewhere, so knowing it's the reed valve lessens my fears.