Drive Belt/Air Conditioner Compressor

[peace_of_soul]

I (and I, in this case, am Eric's girlfriend) have been searching the forums most of the morning to no avail. Perhaps I am not looking in the right places, but if someone could point me in the right direction that would be great.

We have a 2000 Jetta with 180K. We are concerned about a burning smell and a squeal coming from the engine compartment. It doesn't look to be a timing belt issue (timing belt was replaced 20,000 miles ago). The belt to the front right of the engine (as you look at it) does not appear to be turning and the A/C makes a kind of grinding noise when turned on. Same with the vent fan. I explained all of this to one of this sites recommended mechanics and he agreed with a friend who does a lot of work on gas BMWs that it was a drive belt issue.

I'm just wondering if anyone can help me with further diagnosing this issue and give some pointers on making the needed repairs or directing me toward advice already given on this topic.

Really appreciate all the great advice and general comraderie. Thanks a bunch.

 

[ScorpionBoy]

are you sure the serp belt isn't turning? that would be pretty strange, especially if you are getting noise from the AC. put a big blob of white chalk or something benign on the belt to verify its movement. turn off the ac and defrost as well and verify if sound/smells go away. my money is on your compressor being shot.

 

[peace_of_soul]

Compressor was replaced 20K ago, with the timing belt, etc. The belt is definitely not moving, although perhaps wobbling a little bit . . .

 

[tdibigd]

Anything powered by the belt could be seized. If you can, look at the compressor from the bottom of the car to see if the clutch is intact. It's not uncommon for the clutch to self-destruct (happened to me) and potentially clog up the works. I know it's only 20K miles old but you never know.

Take the belt off by releasing tension on the tensioner assembly. Go accessory by accessory and attempt to rotate by hand (obviously with engine turned off) You'll soon find the seized component, be it compressor, alternator, PS pump, tensioner pulley, etc.

 

[eb2143]

As tdibigd said, get the car on ramps, remove the bottom cover, and it will be pretty obvious what the problem is.


I'm assuming you're not driving the car as you don't have power steering or a charging alternator?

 

[Drivbiwire]

No matter what it's coming apart...get to work!

You will need a new belt so don't even think about re-using it after this.

Then you can hand turn all the pulleys and figure out what is happening.

DB

 

[peace_of_soul]

The car still turns over and drives, but has a bad burning smell and squeal.

Will be pulling her apart this weekend . . . girlfriends New Beetle (1.8T) has an electrical short and has to be jumped everytime to operate. If bad things come in threes, we're screwed.

 

[Drivbiwire]

I would not drive it unless you want the repair to be EXTREMELY expensive.

DB

 

[dogdots]

I am replacing my alternator pulley right now and my a/c compressor. Strange noises when it failed. The compressor died electrically (still turns fine by hand). The alternator pulley can fail. Usually you will get the battery light flashing as a warning if the alternator pulley is about to go flying.

 

[tdibigd]

The car still turns over and drives, but has a bad burning smell and squeal.

Yes, even though something is seized, the crankshaft pulley is still rotating under the belt, causing both to heat up significantly....pure friction. The belt is still under tension so the friction the engine's having to overcome in turning the crankshaft is being given up in heat and lots of it. if you're running it in this condition, you're probably going to end up with a mess of melted rubber on your crankshaft pulley...and there's always the possibility of a fire. Equally as unsavory is if the belt snaps and launches itself into the timing belt path. It has happened. I'd stop running it pronto.

 

[peace_of_soul]

The a/c was only working sporadically when I first noticed the smell and the noise - I did put about 50 miles on it, since then.
The last time I was able to start the engine, the a/c compressor seemed to be a source of friction for the belt.
I am now unable to start the engine - even with everything off, it labors to turn the a/c compressor pulley, budging the belt forward a little.
I would like to verify if the a/c compressor or just the a/c pulley has seized. I will take off the belt to check it for wear and to verify that the a/c compressor has seized.
Although i have a replacement a/c compressor, replacing it is beyond my abilities.
Some posters have suggested that my problem could just be low coolant pressure. Could simply recharging the system, using a $40 recharge kit from Autozone, help? (Of course, I need to continue to troubleshoot the system and find out why it's low in the first place, though)

 

[RamMan4x4]

I'm sure you had a good reason, but I'm not sure why you drove the car 50 miles when you knew the accessory belt wasn't turning. The car probably won't start because the battery is dead because the alternator couldn't charge it. You likely damaged other components while driving as well.

If it were the A/C compressor, you wouldn't notice anything if the engine was turned over while the A/C was off because the clutch on the pulley would still be disengaged...this happened to me in my first truck. I don't think the low A/C coolant could cause this scenario either.

Edit: Sorry just noticed the 50miles was the total since you noticed the problem. Thought it the miles driven over the weekend, after everyone gave you advice not to.

 

[tdibigd]

I'm confused. You've said previously that the belt isn't turning at all. That would not be an effect of having low refrigerant. If the belt's not moving, something has frozen in its path. Now, it could very well be your A/C compressor, but being low on refrigerant doesn't make your compressor stop turning.

The car probably won't start because your battery is likely dead. That belt also turns the alternator which charges your battery. No turning alternator, no charging. If you've been driving around for 50 miles, starting and stopping the engine, running the DRLs, radio, blower fans, etc.... then there you go.

 

[peace_of_soul]

My apologies, I can see how I'm being confusing.

The 50 miles is in retrospect - honestly, now that I think carefully, it was 25 miles max.

I had thought the problem was with the brakes - because of the smell, and I hadn't noticed the belt noise yet.

But, after changing the brake pads, I still noticed the noise and smell. I then thought that the a/c compressor pulley was causing resistance - didn't seem to be turning, although the belt still was moving with the engine running. At that point, I (well, my girlfriend, actually) posted for the first time.

I didn't drive it anymore, but I did attempt to start it to look for differences on the belt with the a/c on or off. With everything off, now the engine doesn't start. The starter attempts to turn the belt, I heard/saw it try, but only now isn't turning because the engine isn't starting.

If I take off the accessory belt and attempt to start the engine to verify if the a/c compressor is the issue, could that damage the engine?

Again, gentlemen, I really appreciate your patience and advice. Thank you for being so welcoming on this forum.

 

[csstevej]

No you won't damage anything with the accessory belt removed. The only thing that will turn is the crank shaft pulley, bear in mind no other accessories will be turning . Make sure your battery is fully charged .

 

[TDICADDGUY]

Take the serpentine belt off and try starting, but put a charger on your battery first to make sure you have enough cranking power. Doing so will cause no damage to the engine. The serpentine belt drives the alternator, power steering pump, and A/C compressor. When you pull the belt I would closely inspect all of these pulleys as well as the tensioner pulley, spin them and check for resistance/play.

If you really are not sure what you are doing, try and find a competent mechanic in your area. A guru would not be worth going a long distance for on this job, as there is nothing really TDI specific if it is indeed one of the components in the serp. circuit. But if there is one nearby, by all means take it there as any mechanic connected to TDIclub will not steer you wrong.

 

[eb2143]

My apologies, I can see how I'm being confusing.

The 50 miles is in retrospect - honestly, now that I think carefully, it was 25 miles max.

I'm going to guess you had power steering for those 25 miles. Your accessory belt was turning.

I then thought that the a/c compressor pulley was causing resistance - didn't seem to be turning, although the belt still was moving with the engine running. At that point, I (well, my girlfriend, actually) posted for the first time.

IIRC, Without the A/C clutch engaged the A/C pulley will NOT appear to be turning when the engine is running. Am I remembering correctly, that the inside of the pulley is still when the compressor is not engaged?

 

[RamMan4x4]

IIRC, Without the A/C clutch engaged the A/C pulley will NOT appear to be turning when the engine is running. Am I remembering correctly, that the inside of the pulley is still when the compressor is not engaged?

Every other vehicle I have owned has been this way...so probably

 

[peace_of_soul]

OK, I scrupulously followed the instructions in the Bentley manual to remove the ribbed V-belt (what the manual calls the serpentine). That means that I took out the top connecting pipe between the turbocharger and the intercooler. To get to that, I took off the headlight and the front bumper.
After the belt was off, the engine started and ran just fine (I had charged it with a charger to make sure it was at full juice.) The only pulley that didn't spin freely (besides the driveshaft) was the a/c compressor pulley.

I took a better look at the clutch plate - it busted pretty bad. The actual plate flanges had broken. So, I took it off.
a/c compressor clutch plate

Upon careful analysis of the a/c compressor, I noticed that the center pin of the compressor is off center by 3mm.

I'm wondering if that is what broke the plate. Now, what could do that? I'm guessing that the compressor is totally shot?

A/C compressor replacement will take some coaching, I think.

I still haven't checked the coolant pressure (I'll try to track down a gauge somewhere).

 

[tdibigd]

Bingo!

Same thing happened to my compressor. The clutch disentegrated one day...of course it was in the heat of summer! I found flung pieces of the clutch in the belly pan. It was a real mess.

A/C compressor replacement is not necessarily difficult, but if you want to do it right, you have to get access to an A/C vacuum pump to pull down the system upon replacement but prior to recharge. If you're not comfortable with that, I suggest you do the replacement yourself but take to an A/C shop to get the system pumped down and recharged. Replacing the compressor is not bad at all.

Also, make sure to replace the accumulator/drier at the same time. You might even entertain replacing the expansion valve just for grins while you have the system cracked.

In for a penny, in for a pound!

 

[peace_of_soul]

OK, so I am in the market for an a/c compressor clutch (I have a spare a/c compressor). Since they are not usually sold apart and I am not the only one this has happened to, it looks like I'll be getting a whole a/c compressor.

After the encouragement, yes, I will replace the a/c compressor myself.
And the drier, on recommendation. (I do hope to get away with just cleaning the expansion valve.)

I also will be checking the fans, by shorting the pins in the temperature sensor to see if they run high and low - I've been told that fan failure is a likely candidate for early a/c compressor death.

Any other recommendations before I tackle the mechanical part of an a/c job?

I can't help but wonder about the pin movement off-center. Is that just how a/c compressors fail?

 

[RamMan4x4]

Good find...I doubt it is a case of the pin being off center and more likely the bearing for the pulley let go and that is why it appears to be off-center. If you spin the pulley, you will probably see that the main shaft stays in one location while the pulley has an eccentric rotation.

Edit: The fans are worth checking out, but if that was the cause for the A/C failure, you should have seen the engine overheating as well. Sometimes these things just break...the A/C pump on my first vehicle (94 Ford Ranger) locked up on me for no reason...it was fine until you tried to engage the clutch then it would just start making the screeching sound. I removed the serpentine belt and tried to move it by hand...it moved but it required a hammer to do so.

 

[dogdots]

While you are in that far, please replace the alternator pulley. It is cheap and will fail soon. Also, if you spend $125 at harbor freight tools on a vacuum pump and manifold guage set and evacuate your own system you will be ahead of the game by $200 and then spend $ 5 each for R134a at Wal-Mart you will need 750 g (2 1/3 cans of the standard 340 g cans) the receiver dryer will take up the slack if you put in more than 1/3 of the 3rd can (do not go higher than 1/2 of the 3rd can). If you get the A/C kit from Tdiparts.com you will get the reciever, the compressor, the o-rings, and the oil for less than orielly's just for the compressor.

BE SURE TO WEAR SAFETY GOGGLES when replacing the reciever dryer. BTW, it is much easier to replace the dryer when the alternator and fan are out of the way.

Good luck.

 

[tbone]

I am a newbie here to the forum. I have a 2000 Jetta TDI with 190,000 miles on it. I recently had the clutch replaced due to it literally exploding on me. Anyways, in the last couple of months I noticed a loud kinda hissing noise when I turn on the A/C, since then the hissing sound has stopped but now when I park my car and turn it off, I feel a rumbling shaking in the engine compartment. Is my compressor going out? I still get cold air when driving the car?

 

[peace_of_soul]

Just wanted to explain what happened.

With some extensive coaching from some more experienced guys on the forum (Hevster1, DanG144, and especially Piper109) I tackled this job. (www.autoacforum.com and www.airconditioning.com was helpful, as well) I was able to flush the hoses with mineral spirits and then special a/c flush fluid, replace the a/c compressor, clean the expansion valve, and replace the drier.

Then, I evacuated the system for 2 1/2 hours, and then charged the system with two cans of freon. I realize that leaves me about 80 grams short, but I will check the system in a couple of days to check to see how the pressure is holding. It blows cold, now, but it is october, after all, and I won't be using the a/c much.