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Air Con, swear con!

knicko

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Joined
Dec 23, 2012
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126
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uk
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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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 .
 
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...
 
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.
 
on another note ive just reinstated my rear aircon and it makes a tremendous difference
 
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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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.
 
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!
 
Your early posts indicated a lot of oil was added. It’s rare that much oil leaks out and adding oil without knowing the exact quantity in all components in the system can hydraulically lock the compressor, often punching holes in the valve plates. An overcharged system can also do this (if the system has refrigerant added in a volume for one with rear AC when that has been removed). I think you avoided this, possibly by having a worn clutch. I’ve experienced a screeching noise when my compressor seized. Not good and almost certainly the clutch slipping.

Well done with your fix. Post up where you obtained the parts from and their numbers if you wouldn’t mind, it’ll probably help a few folk with the same issues.
Additional useful info to be found if you search for ‘Frankenstein’ on here, which gives a thread where two compressors were made into one.
 
I also had a horrendous screech and was worried it was the pulley or clutch but tensioning the belt has fixed it for me, seems that's definitely worth checking first before removing pulleys etc!
 
Your post has prompted me to get my aircon re-gassed, what a difference. Nice and cool.
 
Just noticed a request for me to post up parts used in my repairs. Attached photos of the paperwork will hopefully help.
In the end, I replaced/rebuilt as follows:
1. AC pulley which has friction plate material on front... eBay purchase from Germany £54
2. Shaft oil seal and o-rings kit for AC compressor from AP Air Europe £55 (note when fitting oil seal you MUST NOT just slide it over the splined shaft as this will gouge the seal and cause it to leak. There is a special plastic sleeve to go over shaft for the fitting of the seal, but this wasn't included. I improvised with a plastic nozzle from a silicone gun, which was a perfect fit)
3. PAG46 ND8 oil from eBay - £12 for a 250ml tin, which is more than you should need as this would be the total oil capacity of your AC system and much of the oil will still be present in pipes and components. Try to catch what oil you lose as you split the system and just replace with same amount.
4. Replacement o-rings for the High and Low pressure AC pipes that fit to compressor body. Toyota dealer - £9
5. AC pipe from compressor to condenser... this is a two part pipe which has a union in middle and clamps to a bracket behind front grille. Mine was leaking at the union and attempts to split the corroded union and reseal with new o-ring failed so I bit the bullet and replaced whole pipe & clamp assembly - Toyota dealer £203.

When I split my compressor I found no swarf or signs of concern, so I just rebuilt it with the new o-rings and shaft oil seal.
The electromagnetic coil on the clutch pulley seemed to work OK so I didn't change that part (you can take a live off battery and make contact in the grey connector block with engine running to easily test that the clutch activates and you'll see the inner part of pulley spin with the outer belt driven part of the pulley. If you are not sure you have oil in the system, don't leave this engaged too long as you are by-passing the safety cut-out)

I had deleted my rear air con as that is where the serious leaks were evident (so much under-vehicle pipework which is vulnerable to corrosion). Problem is judging how much weight of AC refrigerant gas to replace, having altered the factory set up. I went with 800g of refrigerant and this seems to work well.

If it helps, I found the attached two-part videos a useful guide for compressor split and rebuild:





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I should also clarify that topping up PAG46 oil into the AC system was a bit 'wet finger in the air' in my case. I had split several parts of the system and lost oil from various places, including some that dumped on my driveway as we cut into the pipework to cap it off in the engine bay while deleting the rear AC.
I didn't want to risk under-lubricating the compressor after all my work, although I also recognise the perils of over doing the oil levels and hydraulic locking the system.
To cover this, I topped the oil through the head of the compressor with the H and L pipes disconnected. I then turned the 'inner' face of clutch pulley by hand so that I was slowly pushing the oil through the system and could feel if there was any resistance. Once satisfied it all felt like it was running freely, I connected pipes again and regassed, before running the system up while keeping an eye on everything and ready to kill the power if something looked/sounded wrong.
 
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