VS Air Conditioning switch vaccum leak - where to look?

[Madmatt]

When I turn on Aircon, all I get is a hiss behind dash and no cold air.

I understand that all vents and aircon use vacuum to operate, so yes, I know I have a vacuum leak!! However, the vent controls all operate normally (using vacuum), and the hiss (leak) only occurs when the aircon is turned on.

So my question(s) are;

Where is the best place to start looking? (Obviously behind the dash around the switch or is it on the temperature control unit?)

How do I get to it? (VS executive with aircon switch high up on dash by security light and hazard switch).

Any and all advice much appreciated. :beer chug:

 

[hako]

Can you pls clarify when the hiss starts - you say "When I turn on Aircon, all I get is a hiss behind dash and no cold air. " does this mean when you press the aircon button the hiss start or does it happen when the temp dial is turned to cold (from hot)?

 

[Brett_jjj]

My AC was making a hissing sound when I turned it on ,and also blew hot air.It just needed regassing ,got that done,$100 and no more hissing and heaps cold.Sometimes when you move the dials you get a hissing sound ,this should only last a few seconds,its normal.Mine constantly did it once the AC button was pressed.

 

[Madmatt]

Can you pls clarify when the hiss starts - you say "When I turn on Aircon, all I get is a hiss behind dash and no cold air. " does this mean when you press the aircon button the hiss start or does it happen when the temp dial is turned to cold (from hot)?

The hiss starts when the aircon button is pressed, and doesn't stop until aircon is turned off. I can hear the compressor engaging and the engine resettle into idle speed, but air doesn't get cold.

No hissing when temperature setting changed.
Temporary (normal) hissing when vent setting changed as vaccuum opens/closes vents.

The system is probably due a regass, but I wouldn't have thought I could hear a vacuum hiss when the A/C button is pressed. It is definitely a vacuum hiss, because when A/C is turned off, I can hear it fading away, not stopping instantly...

 

[hako]

Unless I'm wrong (which ain't unusual), the A/C switch is an electrical switch....nothing to do with vacuum.
So the hiss may be due to the low refrigerant or the compressor clutch slipping. I'd go with the former as Brett jjj had a similar hiss.

 

[Madmatt]

Thank you all - will update after refill...

 

[Heathbirley]

How'd u go after the regas madmatt? I've got exactly the same problem with mine. I've already tried the regas but with no luck.. It definitely sounds like a vacuum leak by the way it fades in and out when the aircon is turned on and off. If this is an electric switch, perhaps it triggering a vacuum as secondary.. I'm stumped! And really don't wana pull the whole dash out!

 

[Xeyesp3]

Did anyone found a solution to this I have the same problem