My Car Heater Is Not Hot – Can I Unplug it or do I Have to Get a New One?

Reader Question
Hello I am writing to ask how can you unplug the heater core in my car, or if I have to buy a new one?
Thank You
Cathy T.

Cathy,

You can “back flush” a heater core in your car with a regular garden water hose. Remove the two small heater hoses that are attached to the core under the hood. Take the water hose and run water with as much pressure as you can through both hose ends of the heater core…so you are pushing water in both directions through the core until you remove the blockage. The blockage is usually a bunch of orange rusty water. Then reattach the hoses…you will probably want to drain and refill your radiator with fresh antifreeze too.

To make sure a blocked core is really your problem. With the engine at normal operating temperature grab the two heater hoses at the core under the hood, if one hose is hot and one is cold…you have a plugged core, if both hoses are cold…you either don’t have enough water or coolant in the radiator, have a bad thermostat, have a restriction in the radiator or something wrong with the water pump not circulating the hot coolant through out the engine.

If both hoses are hot and there is no hot air coming from the heater you probably have a electrical problem or some other problem in the dash duct work.