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Wheel2Turn

Air/Con Pulley

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Hi

I heard a squeaking from under my bonnet today, on further inspection I saw the pulley on the air con sticking with the engine ticking over.

Is this a big job ? 

Can I just have the pulley changed or is it a new air con unit ?

I changed the belt a few months ago.

I don't think I can drive it until I get it sorted because I think it might do more damage.

My car Rav4 petrol 2.0 vvti Xt3

 

 

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Not sure I quite understand. Are you saying that when the engine is idling - the aircon compressor pulley is sticking in one position and the belt is slipping around the pulley? Does this happen with the aircon switched on or off? If the pulley is sticking with the aircon switched on - it may simply be a case of a slipping belt when the compressor is under load. Even though a belt is new - if it slips for an extended period, adjusting the belt tension will not remedy the problem - the belt surface simply becomes glazed.

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41 minutes ago, gjnorthall said:

Not sure I quite understand. Are you saying that when the engine is idling - the aircon compressor pulley is sticking in one position and the belt is slipping around the pulley? Does this happen with the aircon switched on or off? If the pulley is sticking with the aircon switched on - it may simply be a case of a slipping belt when the compressor is under load. Even though a belt is new - if it slips for an extended period, adjusting the belt tension will not remedy the problem - the belt surface simply becomes glazed.

Thank you for the reply

What it is I was reversing down the drive when I started hearing a squeaking sound, so I looked under the bonnet and I could hear this rattling/squeaking sound coming from the belt area its not a loud noise.

It was a bit dark but looking at the belt I could see that on the air con pulley the pulley looked like it was sticking not all the time just now and again when engine was ticking over. More like turning slower and then speeding up again with same motion and rotation of the belt and other pulleys. The air con was off

I then put the air con on to see what was going on air con working all okay blowing cold air. 

Look again at the pulley and it still sticking and making a rattling/squeaking noise ?

The belt was fitted about 3 months ago i only had it changed because it was due replacing and I try and  keep up to date with things.

Sorry if I haven't explained it that well, not very good with words.

The belt don't look like its slipping on the pulley it looks like the pulley to me ?

 

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Pulleys can give an optical illusion that they're changing speed or even turning backwards especially if you're also viewing the printing on the back of the belt appearing and disappearing. Realistically, the aircon pulley can't change speed unless the engine speed changes or the belt slips either on the crankshaft pulley or the aircon compressor pulley. The clutch assembly behind the aircon pulley can wear so it might be an idea to slacken the belt and check that the pulley rotates smoothly with the aircon switched off and rotates with some resistance with the aircon and ignition switched on. A worn clutch assembly will often result in a rattling noise though you might not identify this when turning by hand.

With the engine running - spray water on to the belt. If this stops the belt from squeaking the belt needs re-tensioning or replacing. If the clutch is rattling, it is possible to repair it without discharging the refrigerant.

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9 hours ago, gjnorthall said:

Pulleys can give an optical illusion that they're changing speed or even turning backwards especially if you're also viewing the printing on the back of the belt appearing and disappearing. Realistically, the aircon pulley can't change speed unless the engine speed changes or the belt slips either on the crankshaft pulley or the aircon compressor pulley. The clutch assembly behind the aircon pulley can wear so it might be an idea to slacken the belt and check that the pulley rotates smoothly with the aircon switched off and rotates with some resistance with the aircon and ignition switched on. A worn clutch assembly will often result in a rattling noise though you might not identify this when turning by hand.

With the engine running - spray water on to the belt. If this stops the belt from squeaking the belt needs re-tensioning or replacing. If the clutch is rattling, it is possible to repair it without discharging the refrigerant.

Thank you again for your reply

This is what I found out today by looking at it in daylight, I know nothing about air con units on a car and never have had a problem with one before to look in to how it all works.

I found out today there is a clutch on the air con pulley that engages when air con is on, I think I have got this right.

So this is what is happening with my air con pulley/pump

I have marked the clutch on the front of the pulley with a white paint mark so i can see whats happening.

Start engine air con pulley turning with belt and clutch not moving all good so far, after watching for a few minutes the clutch starts to turn then stops and then spin a little stop and then spin again this is when i can hear the squeak.I dont think it should be doing this with air con not turned on in the car but engine ticking over, I'm I correct in thinking this ?

Now with engine ticking over i then turn on air conditioning and the clutch start spinning for ten seconds and then stops for a few seconds and then spins again for ten seconds and so on, The air in the car it really cold so its seems to be working okay.

So I am thinking something is sticking on the clutch and making it make a squeaking noise or rattling noise.

I didnt have much time today to look into it more but i dont think i will use the car untill i have fixed it might do more damage.

Do it sound like a shim missing or something like that ?

Forgot to add it only makes a noise when clutch starts turning or spins.

Thank you again and sorry for the long post.

Edited by Wheel2Turn
Missed a bit out ooops

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I think terminology has caused confusion. The belt turns the compressor pulley at engine speed. The hub of the pulley turns when the clutch is energised - with the aircon off -the hub doesn’t rotate. If the hub is rotating at times with the aircon off - the clutch is dragging ie not fully disengaging. With the aircon switched on, the clutch is not activated continuously - the compressor cycles on an off depending on the level of liquid refrigerant in the system. In this respect, your aircon appears to be operating normally. Each time the clutch is activated, you should hear a distinct click and you may detect a slight change in engine speed.

The rattle and clutch drag would suggest that the clutch unit is worn or damaged. If you search on this forum you’ll find that some owners have repaired the clutch assembly. Otherwise the pulley / clutch is a bolt on unit which can be replaced. 

Might be worth taking the car to a local auto aircon specialist for an opinion.

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On 11/16/2018 at 11:09 PM, gjnorthall said:

I think terminology has caused confusion. The belt turns the compressor pulley at engine speed. The hub of the pulley turns when the clutch is energised - with the aircon off -the hub doesn’t rotate. If the hub is rotating at times with the aircon off - the clutch is dragging ie not fully disengaging. With the aircon switched on, the clutch is not activated continuously - the compressor cycles on an off depending on the level of liquid refrigerant in the system. In this respect, your aircon appears to be operating normally. Each time the clutch is activated, you should hear a distinct click and you may detect a slight change in engine speed.

The rattle and clutch drag would suggest that the clutch unit is worn or damaged. If you search on this forum you’ll find that some owners have repaired the clutch assembly. Otherwise the pulley / clutch is a bolt on unit which can be replaced. 

Might be worth taking the car to a local auto aircon specialist for an opinion.

Thank you again for replying nice one

I'm not very good at putting things into words sorry but we got there in the end.

After watching a few vids on YouTube and with the info from you that you gave me I took the clutch off the air con today and had a good look at it in the garage.

I think it was sticking and that the shim/washers had worn down only one shim/washer left on it should of been 3 shims/washer.

I gave the clutch a good clean with brake cleaner and a little wire brush found a washer that fitted and brought the gap back to 0.65 mm.

All working and doing what it should do so fingers crossed that will do the job for now.

I did ring a repair garage and explained to the guy what the air/com pulley was doing and he said probably a new air compressor.

So for a washer and a bit of brake cleaner that I had already didn't cost me a penny. I did think it was going to cost me a bit to have fixed at first.

There are some good vids on YouTube about the fix if anyone is having the same problem, I didn't like to link them because I didn't know if I could.

Thank you again gjnorthall for you help 👍 😀😎

 

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Excellent. A few people on this forum have repaired the clutch in the manner you describe and saved a fortune. Unfortunately garages and aircon specialists will invariably go for a new / service exchange unit rather than attempt a repair. I stand to be corrected, but I'd see no problem at all in posting links to relevant information in the public domain.

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On 11/19/2018 at 7:10 PM, gjnorthall said:

Excellent. A few people on this forum have repaired the clutch in the manner you describe and saved a fortune. Unfortunately garages and aircon specialists will invariably go for a new / service exchange unit rather than attempt a repair. I stand to be corrected, but I'd see no problem at all in posting links to relevant information in the public domain.

Thank you again for all your help

I don't know why the garages don't repair them today, maybe the time and cost for labour works out the same has changing the compressor, not like the old days when garages liked to fix things and get them going again, It was a challenge back then for the fitters and the garage reputation at stake, its more about money today and how many cars they get through the doors.

I read a few of the threads really good information , I found this vid on the fix, the guy does go on a bit but I found this video better for me, he explains it really good. 

 

Thank you again 👍

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