why wont the heater shut off
If your talking about the blower motor, my info shows two blower relays, high speed and low speed relays, pull the relays, see if it kills the blower. Depending on the vin, there is a fusible link, that sends voltage to load side of relay, that fusible link is hot all the time. Could be relay problem or the hvac control, the hvac control sends voltage to control side of relay. w/o doing some testing I can't tell you which?
Search Chevrolet Corvette Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chevrolet Corvette Experts