Vapor lock, that's insane.
With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are.
The temperature is controlled by the use of an air mix door that is operated by an electric motor/actuator. This door can be jammed or the actuator can be inoperative or have stripped plastic gears internally.
Thursday, October 21st, 2010 AT 2:16 PM