I have never understood why people turn their air con off ever. Air conditioning is just that, conditioning, not cooling like everybody seems to think. I never turn the air con in my V8 off. In the winter, I simply turn the heater temperature dial to red whilst leaving the air con on minimum. That way, the car is warm (or would be if my heater matrix wasn't blocked), there is no condensation and the atmosphere in the car feels fresh. With the air con off, the car feels stuffy and horrible. Try it ! Just put the air con knob on minimum and the flow knob on feet and control the temperature of the car with the hot/cold knob. This will use very little fuel and will mean that your air con will only need re-gassing once every five years and the car will be much more comfortable. Not to mention quieter as this means you can have the windows shut all the time. It will also mean that the system won't fail every Spring due to lack of use !