Heater
Asked by kennedymajik Nov 08, 2018 at 01:33 PM about the 2006 Mercury Grand Marquis LS Premium
Question type: Maintenance & Repair
Sometimes my heater blows cold air. Other times it works fine and blows warm
air. It is an intermittent problem.
1 Answer
There are a few things to check. First is coolant level. Radiator and overflow tank. Next look for a vacuum leak in lines fittings and if equipped a vacuum tank or canister. This problem is usually noticed when the vehicle is under load like going up hill. Another item to check if equipped is the mixing valve. It too can be vacuum or electronic. It’s usually located near the firewall in heater hose tube.