knicko
Member
- Joined
- Dec 23, 2012
- Messages
- 126
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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
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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