It's been proven a million times over that leaving using the AC is more fuel efficient than driving with the windows open whilst you're travelling over 50 or something.

You also can throw into the mix the cost of repairing your modules that fail due to damp.

If you've noticed a decrease in power/mpg then I would say there is an issue with your system - did you run with the car at 50mph on the perfect flat for a few minutes with CC on, reset the computer, take a mote of mpg, turn on a/c and reset the computer etc etc. If not then you cant really claim a couple of mpg…. 

Hi guys....please don't mind if I jump in for a quick question while you are on the subject of the climate control...
I have a MY06 FFRR...my climate control works just fine...temp is nice and cold.
My concern is that when I have the system on...a whining noise can be heard and it's sound increase or decreases with the engine RPM. It obviously related to when the CC system is on...in your opinion do you think this could be the compressor, belt, or a problem with the tensioner??? Or is it just normal?
Thanks for letting me jump in  2006 RR 4.4 HSE
2008 Audi A6

dan_uk_1984 wrote:

It's been proven a million times over that leaving using the AC is more fuel efficient than driving with the windows open whilst you're travelling over 50 or something.

You also can throw into the mix the cost of repairing your modules that fail due to damp.

If you've noticed a decrease in power/mpg then I would say there is an issue with your system - did you run with the car at 50mph on the perfect flat for a few minutes with CC on, reset the computer, take a mote of mpg, turn on a/c and reset the computer etc etc. If not then you cant really claim a couple of mpg….