One very HOT day I drove on the road and , of course, turn on my air speed to the max level (IIII). After 20 minutes when I turn it to next level (III), there was no air came out, So I turn back to IIII and air blew again. After 5 minutes I tried turn it back to III and still no air, so I turn to II and I----no air and I turn it back to IIII and it complete dead. Next day I sent it to my mechanic and he said I need replace the switch panel. Is this true? and what happen? Please advice.