993 Turbo Air Con varies with Load/Turbo Boost

[No Longer]

I know this sounds daft but here it is:
'97 993 turbo, had it for years has always been like this, never worried about it and keep forgetting to ask when serviced.
The Air Con blows only when the engine is off load and is definately in sync with engine speed and load, quite entertaining really as it sounds pretty good. When it is off load it blows hard and cold, when on heavy boost hardly feel anything coming out of the vent accept the tone change - are these fan driven.
Daft eh - any explanations?

[johnycarrera]

Sounds electrical, mine did this recently and some of the fuses had melted together!

[Ian_UK1]

No Longer said:

I know this sounds daft but here it is:
'97 993 turbo, had it for years has always been like this, never worried about it and keep forgetting to ask when serviced.
The Air Con blows only when the engine is off load and is definately in sync with engine speed and load, quite entertaining really as it sounds pretty good. When it is off load it blows hard and cold, when on heavy boost hardly feel anything coming out of the vent accept the tone change - are these fan driven.
Daft eh - any explanations?

The aircon compressor does automatically cut-out at full throttle and cuts back-in when you go back to part throttle - this is normal behaviour, but I don't know if it's relevant to your situation.

[unclepezza]

Could this be vacuum related or the ccu controller might need looking at in the dash? There are several vacuum lines that are close to the rear of the stereo unit, if it's been out for any reason they might of been disturbed

Can't say I had this "feature" on my 993 turbo. Perhaps some other owners will chip in with suggestions

[stewart rix]

I've noticed exactly the same symptoms on mine. I assumed it was a sensible programmed solution to always giving you full power when you needed it, rather than being (slightly) reduced by the air con.

[No Longer]

Thank guys for all of your inputs so far. Picking up on Ian's comment about the compressor made to cut out on full throttle and the re-assuring comment from Stewart that his does this also (well either it is supposed to happen or we both have a problem). I had wondered if that was the design intention but it seems a lot of engineering to make it happen automatically? - if the driver if that concerned about power loss on 400+ horsepower, turning the AC off would be a better solution? As I say thanks for your comments - perhaps more info will be added by others. Hopefully the question will not roll into the area of what HP the AC draws and the merits of having it on or off, not really interested in that; I simply want to know if it is a problem or it's supposed to happen - well see. Thanks again.