When operating the A/C sounds like a vent door opens and closes allowing cold air then hot air from the passenger side dash vents. Is there a sensor or relay involved or do you have to take the dash apart?

 

I had a similar problem on my '03 H2. Drivers side blows cold and pass side blows hot then warm and back to hot. After reading several posts I figured it was a sensor problem. I turned the pass side temp up to 90 and whaala it started to blow cold. I waited a few minutes and it stayed cold. Now both sides blow cold. Problem fixed, no. Problem solved, yes.