Re: [doc] Air conditioning......re-gassing query...(must get done before summer!!!!!)

[Martin Gutkowski <webmaster@xxxx>]

Hi Nick

the dead giveaway for a system low on gas is the compressor will cycle 
frequently (2 or more times in 10 seconds at 3000rpm). If REALLY low on 
gas, the compressor will not fire up at all. The cooling fans are wired 
up to come on when the compressor cycles - this all contributes to the 
"kick" from the engine when it engages. The FanZilla is an elegant 
solution, but expensive. I have my fans wired up to engage continuously 
with AC and each fan is run from a seperate relay.

The seals and internal components are lubricated by the refrigerant, so 
a system that is left to stand is more likely to leak (esp after 20 
years) than a recently re-gassed and used system. I suggest a re-gas and 
see how long it lasts, then you can start looking at a UV dye test.

DO NOT consider converting to 134a - our colleagues across the pond 
consider it because the "drop-in" ozone-friendly R12 replacements are 
illegal over there (but using original stocks of R12 isn't bizzarrely). 
R134a runs at higher pressures and is not as reliable as R12 in our old 
systems. The guy I found used R413 but apparently there are several R12 
drop-in replacements available. I used www.newcenturycooling.co.uk and 
the owner, Greg, has a rare TVR in his garage, so is happy to play with 
the DeLorean - however he does not have the facilities to do leak tests. 
He charged me £40 to vac and re-gas Lex. I have been given the name of a 
place in Kent that specialises in classic car AC but haven't used them yet.

The 1234 fan switch in the dash is independant of the mode switch, 
however the compressor will cycle depending on the temperature of the 
evaporator, so if the fans are off, the evap will stay cooler much 
longer and it will not cycle as much. The "MAX" setting on the AC simply 
recycles the air in the cabin instead of pulling in air from outside.

Hope this helps

Martin

Nick Tomlinson wrote:

> To All, my air-con feels a bit warm at the moment so I am assuming the gas maybe a bit low. I have done the basics and checked that the belt is tight (was loose) and that there is 12v on the clutch line when the air-con is selected at the console. The clutch does engage. I haven't had chance yet to give the car a blast in case the refrigerant just needs a good spurt.
> Has anyone had any problems getting R12 systems regassed? How much does it usually cost?
> Has anyone had the refrigerant changed to R134a and what o-rings/ pipes had to be changed etc with what benefits cost etc...
> Can someone verify if the fan switch is manually off and the air-con on, does the fan automatically cycle to blast cold air into the cabin or does the air-com stay off cycling with the pressure switch. I have the workshop manual but the working isn't that clear to me (not an electrical diagram you see !)
> Thanks all in advance,
> Nick. PMT250X.
> ps My nokia now has a nice Delorean screen saver on my 3310 thanks to Liam.