A/C does not come on right away - PLEASE HELP
 

Hi.

The A/C in my 2006 Mazda 3 (48K miles) does not come on when the car is first started. Nor will any air blow into the car if I simply just turn the vent on.

After about 20 minutes or so of driving at highway speeds, it will kick on.

So:

1) start car
2) a/c, heater, defroster, vents dont work. No air comes out at all.
3) I will turn the a/c to the on positions and leave it there
4) drive around for about 20 minutes
5) a/c kicks on.

This is VERY frusturating. I have made appts. at my dealership to have it looked at, but by the time I get to the dealership, the A/C is working - and they say they cant do anything about it b/c the can't diagnose the A/C when it is working.

Any thoughts?

My first thought is that it is a sensor or thermostat, but could also be a bad connection. You may need to leave your car at the dealer overnight...