on my 85 corvette, the fan wont work on high speed. low and medium work but not high. can somebody help me out?

 

1st, does your car have climate control? Does it have temp setting readout on the dash or does it just have slides? Manual a/c, problem is most likely the control or blower swtich, ATC might be blower control module. [8D]

 

it has manual switches or slides, so it must be a bad switch