Turn the knob for the blower speed. Do you hear the blower speed change? If you don't, then the blower switch could be on its way out (and only low speed works).

What year and how many km on the car? There is a Customer Satisfaction Extended Warranty for some years for the switch issue.

Edit.
01M07 Extended Coverage Program 10 years/150k miles.
"On your vehicle, the heater blower switch may lose function in one or more of the blower switch positions. If this should happen, defrost performance may be affected."

Last edited by Tony2005; 07/28/06 12:41 AM.

"Always do the cheap and easy ones first." 1996 V6 ATX 96K miles