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Air Con, swear con!

knicko

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Hi all. Another air con aggravation post, sorry.

Since my recent purchase of the vehicle, the air con has never worked. Touchscreen works ok but no sound of revs increasing and the magnetic clutch was not activating on the front of the AC compressor idler pulley. The idler pulley runs free so the serpentine belt (recently changed) is fine and the power heater, which runs off the same belt, is all good.

Hot weather and general fussiness about stuff not working when it should, led me to get a local AC service chap around to have a look. He first identified the AC system was empty and ran a leak test, which showed a big leak on the (surprise surprise) under-body pipework going to the rear AC condenser. I don't care about rear air con, so asked him to cap off the rear pipework in the engine bay and I have since ripped all the redundant pipes out, for the sake of tidiness. After a couple of O-ring replacements on some of the unions, I have a gas-tight system.

We added about 4 ounces of ND 8 oil (assuming some original oil would be trapped in the condenser and other parts of the system), and after vacuuming out, we added 800g of refrigerant. This resulted is the AC clutch engaging when the touch screen was switched on, lovely cold air present and the sight glass all looked good.

However, having taken the vehicle for some longer drives, I now get a horrible screeching noise when the AC is engaged. It disappears as soon as the AC is turned off.

I've had the AC chap back again and he has sucked out the system, we've added about another 2 ounces of oil and then topped the refrigerant back up. There are no apparent leaks. However the screeching is still happening. The belt doesn't appear to be slipping and the AC clutch is engaging ok, but that noise is present as soon as the clutch activates. To observe this under the bonnet, I took a live supply from the battery and shorted it to the clutch magnetic coil connector, so I could engage/disengage the AC clutch whilst carefully watching to identify where the noise is coming from. I just can't tell if it's the compressor or the clutch though.

I got the AC chap to suck out the refrigerant again and I have removed the compressor from the car. I was going to just buy a replacement (Denso 10PA17C unit) but with Toyota wanting over £1100 and a local Denso agent wanting over £800, I turned to the idea of pulling it all apart to see if it can be fixed!

The screech sounds like metal on metal to my untrained ear, so I expected to see evidence of scored pistons and bores with swarf everywhere inside the compressor, but not so. The main shaft appears to run smoothly and there is no scoring on the moving parts. The shaft runs through two 'needle' bearings inside the body of the compressor and while these sound a little worn, nothing that should produce that much noise.

Turning to the clutch/idler pulley assembly, the idler pulley runs on a larger bearing which is also not too noisy and no sign of wear in its movement. The mating faces of the clutch and the idler pulley are metal, although the pulley has a circular section of something that is not magnetic and I'm thinking this might be a friction plate material? On pictures of new clutches, the material is more obviously different to the adjacent metal. I'm now wondering if the friction material is there to prevent the metal surfaces slipping when the magnet engages? Could it be that my surfaces are worn and the horrible sound is just the clutch and idler pulley metal faces skidding across each other with the inertia created when the idler pulley is having to drive the AC compressor?

I may be clutching at straws here but don't want to waste a load of money replacing/reconditioning the wrong parts unnecessarily. Any advice please would be welcome.

I have attached photos of the surfaces of the clutch & idler pulley. I am pointing to the area of 'friction' material (which is non-magnetic).

Thanks

Nick

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Grimbo

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Sounds like the clutch slipping,
I think there's a shimming procedure or failing that new one's from Denso are not that expensive ....you don't need the compressor.... surprised the A/C man didn't diagnose it or isn't aware of clutch issues .
 

knicko

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Hmmm, thanks Grimbo.

There is one shim washer between the clutch plate and the splined shaft it bolts to. I wonder if the friction plates wear down and the shim ends up creating a larger air gap than is ideal. This could affect the magnetic contact between the surfaces, causing slippage?

I'm going to rebuild the compressor and then check the air gap on the clutch end (need to find the correct setting for this in specs).

I was also thinking after posting earlier that I could magnetise the clutch coil with a direct feed off the battery (with engine off) and while the mating surfaces of the clutch & idler pulley are stuck together, I will use a white marker pen across the two parts. I can then run the engine for a bit and see if the pen marks drift apart, which would tell me for sure the clutch is slipping.

Tomorrow is another day...
 

MODVRS

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There is a specification for the air gap set by use of the shims (sorry, I don't know what it is for your clutch assembly), there are several YouTube videos on it. The other possibility is the bearing in the normally stationary pulley has had it, they can be replaced. The bearings can be obtained from a bearing supplier using the numbers and dimensions of the old one, they are staked in but can still be knocked out and the new one put back with some "bearing glue" - similar to thread locker fluid.

I think the bearing is the more likely suspect. I assume you've ruled out the idler pulley bearing if there is one and drive belt issues which can also cause noise.
 

Philip amos

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on another note ive just reinstated my rear aircon and it makes a tremendous difference
 

knicko

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There is a specification for the air gap set by use of the shims (sorry, I don't know what it is for your clutch assembly), there are several YouTube videos on it. The other possibility is the bearing in the normally stationary pulley has had it, they can be replaced. The bearings can be obtained from a bearing supplier using the numbers and dimensions of the old one, they are staked in but can still be knocked out and the new one put back with some "bearing glue" - similar to thread locker fluid.

I think the bearing is the more likely suspect. I assume you've ruled out the idler pulley bearing if there is one and drive belt issues which can also cause noise.
The idler pulley bearing was changed a couple of months ago when I did the cam belt etc.
The air con pulley isn’t ever stationary as it turns with the belt. It’s the shaft of the compressor that is stationery until the clutch engages with the AC switch.
I’ve ordered a replacement pulley, which has the friction material for the clutch face in it, plus a new bearing already fitted.
Will see how it works when I rebuild it, with a new compressor seal kit.
Here’s hoping
 
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knicko

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Update… ordered a set of seals to rebuild the compressor, plus a new clutch pulley.
Once refitted and power supplied direct to AC clutch from battery, the compressor was running without any horrible noises, although the refrigerant was still empty at this point.

Got the AC guy back to re-gas it and the system is now working perfectly. Happy bunny and at a cost of about £100 for parts and postage, I’ve saved myself a lot of money compared to replacing parts from Toyota or Denso dealers.
 

Chris

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Nice one. Well done. I did exactly the same and it ran for about a year and then suddenly the gas was all gone. Just haven't had the energy to track down the source of the loss. But it doesn't seem to be the rebuilt compressor!
 
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