OMEGA Air Con

Basically, you don't. Go to a garage that does air con and is personally recommended. They will connect up a machine that will remove and weigh the old refrigerant, check whether it contained any dodgy gases (such as butane) Vaccuum down the system and check that the pressure does not rise. Put in the appropriate amount of oil, leak detector and refrig. gas. The running pressures and temperatures can then be checked, leaks can be looked for with an UV lamp and when all appropriate repairs are done the system will work. Repairing air con is time consuming and expensive, even more so if people have messed about before.

your qs in order:

1. Any refrig. supplies seller will sell you the appropriate set of gauges, external threads for old r12 systems, internal for newer r134. (200 pounds)
2. Buy a vacuum pump (500 quid and connect to the gauges in 1.
3. AFAIK butane will not harm the system if removed before running,
4. Both "sides" are connected together (do you understand how it all works ?) Pressurising to 200 psi with nitrogen would not hurt anything, as long as it is vaccuumed out afterward.
5. Any branch of BoC and other gas suppliers will sell you the appropriate gas. (150 quid a bottle)

HTH MrCheerful

Thanks for the reply.

The reasons I want to have a go myself is summed up in your reply. Several so called air conditioninng experts have leak detected my system using all their wonderful test kit and have all come up with different leak points, including the compressor. As I said the car is old, and it doesn't take long to spend more than it's worth on new bits and several recharges, much more than £150 on a bottle of gas. Though I'm not a refrigeration engineer, I do have a scientific background and I think I know how air conditioning works I and buy and sell laboratory equipment and know how to use it. For instance I have access to superb vacuum pumps, nitrogen gas etc., but I don't have the connections to the valves on the car. I can afford to spend a lot of time doing the job, and do appreciate some of the problems, however it will not be a major calamity if I fail and it only costs me the price of a gas cylinder and schrader valve connections, and I don't find where the leaks are.

regards

Dave

appropriate

In that case, establish which gas your car uses. Hopefully it is an R134 type. This can be checked by a sticker under the bonnet or by looking at the valve connections. For R134 your valves should have an internal thread. If your car has an R12 system (external thread like an overgrown tyre valve connector ) then it really is not worth bothering about, as the gas is no longer available and conversion is expensive and really difficult. Having established it is R134 go to an industrial refrigeration place such as NRC and buy a set of gauges, these have a manifold with various taps and several hoses. These will allow convenient access to the system to check, purge and refill as appropriate.

mrcheerful