Make sure the coolant is full. Make sure the engine is warming to a normal operating temp. Make sure both heater core hoses get hot. If they do, check the blend door. If only one gets hot, flush the heater core.
Feb 14, 2011 at 1:25 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.