help / advise on air-con problem on mk3 2.2dci

[age9000]

when i switch on the air-con the light comes on, the engine tone changes
but the clutch on the air-con pump does not engage

any pointers anyone can give ?
ie where are the fuses and i guess a relay located ?
i did not want to randomly pull fuses/relays in case i upset something

Age

[jack daniels]

if the gas press is low then the clutch wont engage. Has it had very little cooling effect recently, or been unused since last summer? Maybe it's been a while since the gas was refilled?

when you say the clutch dosn't engage, are you observing the center of the clutch pulley on the compressor? why is the engine tone changing then? is that the cooling fan starting?

Often the cheapest way to do anything with A/C is to get a drain & refill service done. Many places have special low prices since its only about 10-15 min work while the process is done by a machine.  I'm a bit scepticle to the non specialist garages doing anything with A/C however if you stay and watch and make sure they have the correct spec for your vehicle regarding test pressure and fill volume then it should be ok. I would pay a bit more if necessary and get a A/C specialist to do the service.
        
If it works again after the refill then it's a cheap fix.
the fuses should be shown in the user manual. There is one wire attached to the compressor on the underside near the pulley, you could check that with a mirror.

My local dealer's price was 4 1/2 times higher than the cheapest price last time I got it done, however the cheap garage used the wrong spec and filled too much gas. After I noticed that on the print-out a day later they repeated the process for free with the correct amount of gas. Unfortunately after the fill equip. was disconnected I heard gas leakage from the compressor out of the front bearing seal.  I started the engine imediately and turned on the A/C for a minute, it stoped leaking gas, audibly anyway. The low price garage then started talking about leak finding over the entire system, dissasembly and UV lights.

       I loged on to ebay bought a new compressor and gas filter and got them fitted at an A/C specialist, costing 3 hrs work. Apart from installing the accesories belt about as wrong as its possible to get it, they did a good job.

[colin4255]

I agree with jack here. My reent experiences with air con on the espace are a case in point. Gas would leak away after about a month, then we would get similar circumstances to what you describe. To work properly they have to be fully gassed up or the failsafes cut in and the thing won't work if its devoid of gas. Points to note:

1. You should use your air con at least once a month, even in winter to make sure it runs. If you leave it off, the seals in the compressor go dry and after 4 months of winter, you turn it on and hey presto - no gas. The main seal relies on a film of oil between two large flat washers and if you leave the compressor off for any length of time, the oil dries out and the gas leaks away. (I am simplifying here, but thats about the jist of it depending on the type of compressor you have fitted).

2. In my case the leak was eventually traced by a good air con servicer, to be a leak in the casting on the compressor itself. Renualt failed to see this as they tend to check for leaks in pipework and fittings only. My guy spent 2 hours running the air con on and off on a ramp, and in the end found the minutest trace of leaking from a cracked compressor casting. A second hand compresor for £40 off Ebay cured that issue and it worked fine until it was written off in an accident recently (see seperate story)

3. You could always go to your local car emporium and buy a cannister of refrigerant and in about three minutes, fill it yourself. In the Uk costs about £30 - £40 depending on where you buy it from and the instructions are a doddle to follow. It may just be out of gas - if not used for a long time it would leak away basically for reasons stated in (1) above.  More usually however its likely to be due to a leak somewhere. You can buy all sorts of stuff to seal leaks, but how well they work depends on how bad the leak actually is.

Find a good independenat air con specialist and let them have a look. The good ones know what they are doing.....

[jack daniels]

Even if the system is "leak tight" with no significant leakage, the gas press will drop over time regardless. About 5 years +/- is probably normal. If the system has not had a refill for 4-5 years or more then it may not have a serious leak at all. It may well work fine for several more years with just a refill and some use.

If the system is filled DIY, how is the volume or weight of gas measured?
 Is there an asortment of various size gas cannisters available?