have hot air cominh thru vents even when the dash lever is to the left which should shut if off. took it to the dealer and they changed the heater control valve which was faulty. my temperature compensation board is erratic and gives different readings. i disconected the coolant sender wire and touched it to ground with the key in run position and the needle didn,t go to the top. this means that the board if probably defective. my thermosat seems to be working properly so i don't believe the car is running hot. dealer wants to relace the board and thermostat which i believe won't solve my problem. any suggestions??