RepairPal's independent, master mechanics track down the best of the best in auto repair. Learn more »
Get the latest advice about your car
when the heater controll is switched on heat, what opens the water flow to the water heater, is it manual or electrnonic
Sounds like the blend door is not opening to the heater core... Either broken blend door or blend door actuator. Need to find out which. Is the engine temp. getting up to regular operating temperatures?