Aircon Compressor problem

[fossil]

In the last week or so the aircon compressor in my D1 TDI seems to be playing up. When I start the car from cold for about 10 - 15 seconds the magnetic clutch continually engages and diengages making a loud clicking noise. It doesn't do it all the time but most times when it is cold. I haven't noticed it happen when the engine is hot. It doesn't seem to effect the working of the aircon as it still cools OK. After the initial 10 - 15 seconds it seems fine.

Has anyone else had this happen or has anyone got any ideas why it is happening and how I can fix it.

Thanks

Iain

[ladas]

[quote=fossil;523060]In the last week or so the aircon compressor in my D1 TDI seems to be playing up. When I start the car from cold for about 10 - 15 seconds the magnetic clutch continually engages and diengages making a loud clicking noise. It doesn't do it all the time but most times when it is cold. I haven't noticed it happen when the engine is hot. It doesn't seem to effect the working of the aircon as it still cools OK. After the initial 10 - 15 seconds it seems fine.

Has anyone else had this happen or has anyone got any ideas why it is happening and how I can fix it.

Thanks

It could be just dirt/grit/dust in it, then just remove, clean with kero/white spirit/petrol ..........wipe clean, leave to dry out then reasemble.

However it could be the windings in the clutch getting weak, difficult to diagnose, but if the clean out doesn't work It would my guess that is the problem.

If it is - you need a new clutch.

Not hard to do.

[fossil]

Thanks mate, I'll give it a clean on the weekend and see how that goes.

Iain

[Rovernaut]

Also check the compressor clutch relay and make sure it's holding current, if faulty it could intermitantly cut in and out

[mcrover]

Yeah check the relay and also it could be the high pressure switch or wiring to the high pressure switch earthing out somewhere.

I havnt heard of many giving up the ghost or dust getting in and causing it as it needs power to activate it.

put a test light on it or (wow a use for scotch clips) use a scotch clip to wire up a light in the cabin to see if when it happens you are getting power at the clutch. If it is pulsing then It is more than likely the relay.

[ladas]

Yeah check the relay and also it could be the high pressure switch or wiring to the high pressure switch earthing out somewhere.

I havnt heard of many giving up the ghost or dust getting in and causing it as it needs power to activate it.

.

Unfortunately as there are two plates, similar to a normal clutch, dirt/dust/grit does cause this problem.........we see it all the time.

...........and the electro magnet windings do give up........over time.

Not sure what is meant by "as it needs power to activate it"

Just to explain briefly the system - there are two metal plates which are held a few mm's apart. When the clutch is energised is stimulates the coil to magnetise one of the plates - and the two are pulled, and held together.

If there is dirt/debris/grit/even oil on the plates they skid/skip and bounce out. The same happens if the coil for the magnet is weak. Plus as said earlier if the relay is weak/faulty not supplying a good 12v supply.

On the pressure switch ...........as it is only during start up it would be likely to be low pressure (not high pressure), but unlikely as if it is LP, as when the system runs the LP drops from a static reading of between 80 and 100 psig to between 30 and 40 psig when operating 'normally' - the cooling is working normally, after the initial hiccup - so LP can pretty much be discounted, as well as HP.

If it was wiring I doubt if it would 'go away' after 15 - 20 seconds. Possible I suppose but it would hardly replicate each time, just as it starts. I would have thought that if the wiring was earthing out it would do it all through the process .....not just on start up.

[fossil]

I've never attacked an aircon compressor before so had a bit of a search and came up with these instructions
http://www.warnerelectric.com/pdf/819-0361_P-1411.pdf

Is this pretty much what I can expect. I would like to start by cleaning it up as suggested by Ladas to start with. In that case do I only have to disassemble as far as step 2 on this web site.

Thanks

Iain

[mcrover]

Ladas, I wasnt wholely discounting Dust grit etc I just said that I hadnt seen it.
As far as it needs power, I was refering to electricity.
I have to deal with air con crap all the time on the tractors and it is a pain some times but this to me sounds more like a relay or definatly an electrical problem.
I did realise later on that it cant be the HP switch as it was on start up and I dont think the one on the TDI has a low pressure cut out but I could be wrong.
Corrosion on the contacts of the relay tends to make the pulse.
If it were grit and stuff it would more than likely not disenguage at all but if you have it switched off when you start it and it still does it then more than likely that would be the problem, Im not 100% on the windings being weak, it's another diffinate possibility.
Mine was doing a similar thing and it was the activator wires had been worn by a broken belt and it was cutting in and out but it was doing it irregularly so Ladas is probably right about that.

I dont mean to take over your thread but a fault im chasing at the moment is on one of our tractors the air con works half the time fine but then wont work and when you put the guages on LP is fine but HP is low and then HP will then spike to the point that either the HP switch will trip or it will blow off the OP valve.

Air con bloke is stumped, manufacturer is stumped I think compressor is stuffed.

[fossil]

mcrover I haven't tried starting it with the AC off but will try that tomorrow and see what happens, from your last reply are you saying that if it still does it when switched off that would probably indicate dust etc in the clutch. Sorry if I sound a bit vague but aircon is a whole new world for me.

Iain

[ladas]

I've never attacked an aircon compressor before so had a bit of a search and came up with these instructions
http://www.warnerelectric.com/pdf/819-0361_P-1411.pdf

Is this pretty much what I can expect. I would like to start by cleaning it up as suggested by Ladas to start with. In that case do I only have to disassemble as far as step 2 on this web site.

Thanks

Iain

Before you start pulling it apart test the power supply first, that's the easiest.

Disconnect the clutch power lead, and connect a length of wire to it (clutch end) that will reach the battery poss terminal.

Start the car, switch on the AC, then touch the extended wire onto the poss terminal, this should engage the clutch - if it starts without the jumping in and out. The problem is with the wiring or relay.

If it still jumps in and out then the issue is more than likely the clutch.

Most LR A/C clutches are 'slightly' different to those shown on warners.

Generally, the easiest way is

1. Disconnect the power wire/connection to the clutch.
2. Without the engine running, run a temporary wire from the battery + poss terminal, connect it to the clutch wire. This will energise the clutch (or should - fault dependant) and hold the clutch tight enough for you to undo the bolt.
3. Quickly partially loosen the nut on the front of the clutch - just so it's loose.
4. Disconnect temporary wire AS SOON AS POSS.
5. Remove drive belt for compressor.
6. The front of the clutch should pull off - it will be tight, sometimes you need a puller, but normally - if you take your time - it should budge - soft even taps with a wooden or rubber mallet.....but please make those taps SOFT.

If you tell me what the compressor is, I should be able to tell you which clutch is used - and if the need be the clutch bearing