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Heating System Maintenance

Basic maintenance on your heating system is relatively simple and easy to do. And, doing it on a regular basis will not only help with your overall driving comfort, it will also help prevent overheating, which is the most common cause of breakdowns.


The heating system works off of the same coolant that circulates throughout your engine. It is circulated from the radiator through a series of hoses and the heater valve into the heater core. A fan then blows the hot air into the compartment.

In the following procedure, you will learn how to change your antifreeze (which should be done every 30,000 miles or so), as well as install a new thermostat. To do this procedure, you will need: socket and screwdriver set, safety goggles, antifreeze tester, a clean pan, a knife, a freshwater flush kit, a garden hose and several bottles of antifreeze. You may need to replace the thermostat and heater control valve.


  1. Getting started:

    Unscrew the pressure cap on your radiator. WARNING: never release the pressure cap if the engine is warm. Always wear your safety goggles when working around units under pressure.

    Take your antifreeze tester and insert the tubing into your radiator. It will show you to what temperature your antifreeze is effective. If the temperature in your area will get below its effectiveness point, it is time to change the antifreeze. It is a good idea to change the antifreeze periodically, since, over time, the antifreeze can turn acidic and eventually corrode the radiator.

  2. Starting the freshwater flush.

    Although chemical flushes can be effective, nothing works better than the freshwater flush to get rid of all the accumulated sediment, contaminants and rust. To start the procedure, place your clean pan underneath of the radiator and open the petcock valve on the bottom of the radiator, which allows the antifreeze to drain out into the pan. After it has stopped draining, shut the valve again. WARNING: Antifreeze is toxic. You should always keep children and pets away from it. Also, make sure you always recycle your old antifreeze.

  3. Install the T-fitting.

    Take your knife and cut the heater inlet hose. Take the T-fitting from your flush kit and insert it into the hose using the hose clamps. Then, take the radiator adapter, attach a hose to one end and attach the other to the radiator. Put the hose into your drain pan.

    Next, screw your garden hose into the T-fitting on your heater inlet hose and turn on the hose. At this time, water and antifreeze should start to drain into the pan. Start the car and turn the heater on max. This will backflush antifreeze in the entire system.

    As soon as the water draining from the radiator starts running clean, stop the car and the hose. Open the petcock valve again, and drain the water. Don't forget to also empty the overflow tank that is beside the engine.

  4. Replace the thermostat.

    A new thermostat is like low-cost insurance for your car. It works well to make sure that your engine doesn't overheat and gets to operating temperature quickly. Remove the thermostat housing and unscrew the thermostat assembly. Simply take the new one and put it back into the socket. Before you replace the housing, attach the gasket to it for easier installation.

  5. Replace the antifreeze.

    Most cars will require a 50/50 mix of antifreeze and water, although in colder climates a 70/30 mix is recommended. Check your owner's manual to find out exactly how much antifreeze you will need to put in. Fill the radiator and reservoir with antifreeze first and then add water to fill it to the top. Finally, replace the pressure cap and you are done.

Always work slowly and carefully, and you should be able to complete this task successfully. If you don't feel comfortable in doing any of the procedures, don't hesitate to take your car to one of the ASE-certified technicians at Pep Boys.