Do you want the Road Tax system to change? Do you have thoughts on the potential changes to the Road Tax system? | No thanks
air/con new theory - Michael
just read a note on a usa web site that was discussing the pros and cons of leaving the air con on all the time. There was general agreement that the system should be left on all the time or used regularly to keep the seals in good condition and prevent premature failure. Until one "veteran" member stated that this was true of old systems using R12 gas, but the new systems use R134a and have polyalkylene glycol as the lubricant, a different elastomeric seal material that does not swell and, therefore, it is not necessary to occasionally run R134a systems to prevent leaks.

Can any air/con experts confirm the theory?
Re: air/con new theory - Perky Penguin
And can any aircon experts tells us which makes and models of car use which refrigerant or when was the general change over date - please!
Re: air/con new theory - Dave N
General changeover date was 1993, when they changed from R12 (tradename Freon), to R134a. Some were earlier, some where later. The post further down can tell you how to identify the type used. But if the year of manufacture is before 1992, or after 1994, then it will be one of these. Beware of Jap imports though, as they didn't do the change until much later.

As far as I'm aware, R134a and PAG oil still helps seals to stay fresh, and running the a/c not only does this, but also keeps the compressor and valves lubricated.
Re: air/con new theory - Andrew Tarr
I think you may find that all fluorochlorocarbons from America are trademarked 'Freon', not just R12 (as implied here). It is a generic name which has been used for decades.
Re: air/con new theory - peter todd
there should be a plate under the bonnet which states the type & volume of gas used in the system, if the system has been retro fitted there should also be a new sticky info plate with all the details at the time of conversion.

if no info then look at the compressor & see if it has two small caps/covers,if not there then trace the two pipes/hoses out of the compressor until you find them,

if they are both the same size and when screwed off there are threads on the out side of the fitting then you are on R12.

if the threads are in side the fitting and there is a "groove" running around the outside and the caps are two different sizes then this is a R134a system.

DON'T DEPRESS THE VALVE CORES UNLESS YOU WANT TO RISK GETTING SPRAYED WITH GAS & OIL!

all systems benefit from being run at a low setting to keep the gas circulating as this takes oil round with it to lubricate everything.

best advice is to to use your time now to find a good air-con repairer with a good track record & if you intend to keep the vehicle, then have the system serviced correctly (we change filter-dryers or accumlators every three years to avoid the dessicant from breaking down & going round the system)
Re: air/con new theory - Perky Penguin
Peter,

thanks for that info - I'll check it out under the bonnet!
 

Ask Honest John Right column

Value my car