air con

[daverav]

hi, i have recently had my air con re-gassed and it still doesn't work!
i have change the radiator temperature sensor ready for me to do the viscous fan delete.

when i press the air con switch the engine note changes but the clutch at the front of the compressor is not moving and the radiator fan is not coming on at the same time although the low speed fan will come on when the car gets up to temperature.
i have switched relays over and checked the power lead to the compressor and it would appear not to be getting any power to it (fuses checked and ok)

any ideas

cheers

 

[mrscalex]

The fans can seize. Including starting initially then seizing as the bearings warm up.

Your compressor may be knackered.

You may have a leak in the system and lost your gas pressure.

 

[t-tony]

You could temporarily feed a live to the compressor to rule it out. Use a power probe or a length of cable with a switch in it? You don't need to have the engine running, when you feed the cable at the compressor you should hear a definite click as the electromagnetic clutch is pulled in. Usually you can also see it pull in if you watch the pulley closely.

Tony.

 

[daverav]

You could temporarily feed a live to the compressor to rule it out. Use a power probe or a length of cable with a switch in it? You don't need to have the engine running, when you feed the cable at the compressor you should hear a definite click as the electromagnetic clutch is pulled in. Usually you can also see it pull in if you watch the pulley closely.

Tony.

Tony, have run a live feed and it does work I can see the clutch being pulled in is there any other relays connected ?

 

[t-tony]

To be honest Dave my next point of call would be the system pressure switch. If you've had the system pressurised then the switch could be faulty. I had this on my Audi A4 some years ago. A code read may show this up? If it is then you would ne the system emptying before replacing the switch. I'm not sure if it is possible to simply bridge the pressure switch but I don't see why you could not try this.

Tony.

 

[roadvoyager1]

The rubber seals on the pipe joints "dry out" if the system is not used fairly regularly. Could be the gas has been lost through one of the joints.
You will probably need to get it regassed again to find if pressure has ben lost. There should be a dye in the gas that stains any leaking joints and this can be checked for using a UV lamp.
The seals on mine were simple o-rings made , I believe, from neoprene rubber. Perhaps @t-tony could be kind enough to confirm.
This link should show you where the seals (gaskets on diagram) are located and BMW part numbers http://www.realoem.com/bmw/enUS/showparts?id=CN52-EUR-03-2001-Z3-BMW-Z3_30i&diagId=64_0717.

 

[roadvoyager1]

Link added.
I would suggest checking out the simple things, like loss of gas, first before progressing to more complicated possibilities.

 

[t-tony]

Yes there could be a dye in the system if it was added at the time of the recharge. Not all AC refrigerant has a dye combined some machines like ours at work require you to add dye when programming the machine.
It is not cheap stuff and unless a customer tells you the whole story and you don't know if there's an ongoing problem or even an historical one you don't use the dye every time. The "O" rings are made of neoprene. We rarely have to change these though but bear in mind these cars are of a certain age and getting the components apart is often more challenging than simply replacing the seals.

Tony.

 

[Nodzed]

If there is a leak and the pressure / gas has again escaped (did the re-gassers check? they should have) the power to the compressor is automatically cut to protect the unit. Also if the dryer is water logged the same result. If the system has a leak and open to the atmosphere the dryer must be changed as it will get saturated by the moisture in the air.