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· Registered
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If you do decide to do it, don't go to VW as they just farm the work out. For ?50 you can get it regassed from a specialist. It is probably worth doing soonish, turn the air con off then on a low speed and see how long it takes to get back to temp.
The dealers I know dont 'farm out the work' and most 'local specialists' use a 'non standard' mix of gasses rather than the correct 'R132a' because they are cheaper, but at the same time less effective and contaminate the seals in the system.

And vw recommend an air-con service every 2 years, this includes full system re-gas and replenishing the oil in the system which is just as important for keeping the seals fresh and the moving parts fully operational.

But each to thier own [;)]

· Registered
807 Posts
Don't believe the hype about re-gassing, an a/c system should never lose refrigerant gas and never require re-gassing.

The oil in the compressor shouldn't need replacing, just about all non industrial air conditioning units are sealed for life and an oil change is not possible.

If the system is short of refrigerant then there is a leak and it must be found and repaired before recharging and not topped up.

If a dealer tops up refrigerant in the system and the authorities find out, they will be in for more than a slap on the wrist.

The correct refrigerant is R134a which almost every refrigeration engineer in the land will carry in their service vehicle.

The ammount of refrigerant in a car would cost a refrigeration engineer about ?5.

Tip: Run your a/c occassionally throughout the cold season to keep the internals lubricated and prevent seizing ie. to de-mist windows quickly.

Its no hype about regassing, air-con systems can lose up to 10% of its gas through (ozmosis I think its called) and at the same time moisture can enter the system.

You are correct about industial systems as they are 'welded/soldered shut for life' and this cant happen to them but cars have joints with seals so they can be removed and stipped down for any work/repairs to the cars other components and there is no way around this fact as any manufacturor will confirm.

The oil in the system is 'hydroscopic' (absorbs water) similarly to brake fluid (and brake fluid is affected by ozmosis at the flexi hoses and resorvior which is the reason for adviced renewal every 2 years) and as you dont want water in the aircon system as it operates internally at sub-zero temps and as water freezes would most probably damage the compressor and or expansion valve (not cheap)

No body can just simply 'topup' a system, an aircon system needs to be vacummed and the gas thats removed measured by its weight in grams and only the correct about should be put back in otherwise you might over-pressurise the system and cause damage (anyone still reading can go check thier landing panel under the bonnet, theres a sticker tells you the abount your system holds in grams and it tells you that its R134a that is used)

Anybody working with aicon 'including vw dealers' that are found venting the gas to open air however are in for a big fine if caught, minimum ?2500 for the person doing it and minimum ?10000 for the company they work for.

The gas is not available in ?5 sachets, you require to buy a bottle that holds the amount for about 20 refills, and many backstreet places still get the cheaper stuff and dont say otherwise.

Your tip is correct, however the new polo, golf v, touran, and other new models coming out dont have a clutch on the compressor and even when the aircon is turned off will run at aprox 2% so the system is kept lubed and operational which takes the ownus away from the owner having to remember to run it, therefor less aircon problems longterm.

The wrong facts can be costly [;)]

· Registered
807 Posts
The a/c system is a sealed unit so if all is well will not lose refrigerant unless the parts used leak.

Havn't heared of 'ozmosis'.

You can top up a system as long as it has some charge in it and you purge the charging lines through charging to the sight glass if the car has one, or untill the suction pipe entering the compressor comes back cold with the engine revs at about 2500rpm, however this is not ideal but it does happen, believe me.

I believe a 2 year prison sentance is the maximum for an engineer venting refrigerant, at least thats what I heared. Could be wrong on that one.

I stated that the amount of refrigerant a car requires would cost a refrigeration engineer about ?5 ie. from the dumpy bottle of about 7-10kg. I didn't refer to sachet's.

Are you an engineer yourself or have you been reading a service manual.

Maybe the equipment used is of inferior quality to the rest of the trade so the dealers expect leaks, don't let them blind you with science, vehicle a/c is quite basic.

[8-|] interesting topic, well for me anyway..
Not knowing what osmosis is clearly shows you dont fully understand what your talking about, osmosis is specific to fluids. ie. for cars - water through the rubber flexihoses (which does happen) wheras the prosess is known as diffusion in more general terms, heres the definitions below, both the same thing but osmosis is specific to fluid and diffusion covers all types of particles.

All manufacturors expect up to 10% diffusion loss per year for systems running R134a, thats the manufacturors not the dealers.

Osmosis : Diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane.

Diffusion : the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one of lower concentration .

Not that I want to sound derogitary but kwick fit fitters are tyre & exhaust engineers, so I wouldnt put any more faith in a refrigeration engineer, like you say its quite a basic system.

I hope Im thought of as helpful on here, whether or not Im an engineer or have read a service manual. I might even write sevice manuals, who knows, but my facts are always correct before I put them up for anyone to read.

Basically you dont know the full facts on aircon.

Just found this - not the best but it goes on about molecule size affecting the long term loss or 'diffusion' and it mentions hygroscopic oil, which I spelt hydrocopic doh!

My spelling never was good.
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