How do they pressure test air con? Do they pump it full of normal air and see if it holds pressure or do they apply a vacuum and see if it holds negative pressure?

The reason I'm asking is my XR8 has air con that isn't very cold because the gas is probably leaking out. I had it checked for a fault but they said it was low on gas. They pressure checked it and said it was good so they filled it up. Worked great for about a week then it slowly lost its temperature over 3 months.

Now if they pressure check it using a vacuum that would pull seals in and doesn't actually check the system as it is under normal circumstances (pressurised).

Anything else I've missed or you know more about air cons please let us know.


On my XR6 since I've had it I've had icy cold air con the last 3 years.

When air con is checked it is sucked into a vacuum for at least 1/2 hour and then closed off and monitored for at least 1 hour ( IF IT IS DONE BY COMPETENT A/C SERVICEMEN AND NOT COWBOYS) also after the system is regassed dye is added so the system can be checked at a later time with an ultraviolet light to see any leaks.
The usual problems with ford A/C are leaking condensers (the radiator in frint of the vehicle radiator) and evaperators (the one inside the heater box) which necessitate the removal of the dash.

s**t thats crap. Why test in a vacuum when the system is pressurised?

I'll need to go back again and get them to find the leak. Pray to god its not the evaporator.

System CAN be pressure tested but it is not as accurate and you waste gas which is fairly expensive

Can't you use normal air and then evacuate it and replace with R134A?
I'll talk to my local Deering Autronics.
Thanks GTBob.

with the current laws they HAVE to be pressure-tested before regas and it's done with nitrogen. u cant use normal air because it has a high moisture content which f**k everything if u cant get it all out.

one of the reasons they evacuate(vacuam) the system is to get all the air or moisture out. by applying a low pressure to the system it lowers the boiling point and in theory the moisture steams off.

as gtbob said it takes a minimum of 60-90 minutes just to vac the system down and check for leaks.

if u've already had it regassed recently then it should have uv dye in it which will make finding the leak a piece of piss.

Cool. Thanks. Will get it done after Christmas when everyones had a nice break and refreshed.