Hi All, 2011 TDV8 air con has started hissing like a snake constantly, to the point where I have to turn the AC to drive it’s so annoying!

The hissing appears to be coming from the centre vents and the AC performance is poor (I.e. not much cooler and humid air). The noise stops slowly once you turn the AC off, almost as if the system is pressurising.

I can’t see any leaks to the system, although AC systems are not my area of knowledge.

Any ideas, regas?

Car is and always has been faultless otherwise.

Thanks, Chris

The failure of the control valve inside the compressor is the usual reason for the AC to not work on these cars but not sure how it can cause a hissing sound. Plenty of info if you use the search function  2012 TDV8 Vogue (L322)

Although I work on large fridge and A/C systems when at work, I am not used to working on car systems or this small...but...if the system only produces humid, and cool not cold air then it could possibly be leaking gas or has lost lost most of the gas. The evaporator section where the the fridge liquid turns to gas / cools thus cooling the air in the evaporator / air cooler section...this is situated in the air flow near to the vents. I could be that you are hearing a gas leak, never heard one that bad in a car though that you can hear...but

The other point is that if when you turn the A/C off, this will stop liquid reaching the expansion valve situated at the evaporator, thus the remaining gas in that part of the system will slowly leak off down to atmospheric pressure with the noise decreasing as the gas all leaks out.

This is not a definitive answer, you can buy a re-changing hose / gauge quite cheaply, connect that to the top up line and the gauge will tell you the pressure, try this with system running, this will indicate if you have lost gas, if so you probably have a leak.

If the A/C does cool the air 'slightly at this point then it points to the overall system working as it should but struggling due to low gas level, my guess is that soon there will not be enough gas in the system to allow it to run. As above, the top up tool with incorporated gauge is around £20 to buy and will have instructions as how to use - or go to a local place that does A/C and ask them to check the system.

If you have a leak, then legally the system must be de-gassed by recovering any gas left, system repaired then tested before re-gassing. Hope this helps

Now back to preparations for our local Coronation party on the green with all the neighbours, good excuse to have a knees up with numerous libations, and tasty comestibles, mind you, usually, we don't need an excuse

For all those having a coronation party, have a good time