Heat and AC shuts down on highways

I have a 2000 S 430 with a problem, heat and AC works fine during local driving but as soon as I get on the interstate and get to a steady rate of speed climate control just shuts down. I can hear the fan noise but no air comes out. This is with the heat and the AC. Anyone else have this problem or hear of this on these cars?. Any help or suggestions would be greatly appreciated. Trying to avoid the delear. Also does anyone know of a good mechanic in the Wash, DC area usually go to American Service Center.

read the fault code.

Sleepwalker, what is the fault code?

the computer will store the problem on memory.

bring it to the workshop with proper equipment.