How does the car heater work?

heater core

A heater core

The car heater is designed to keep you warm on cold days. Inside the heater are several components that all play their part in blowing hot air into the drivers / passengers cabin. Most modern cars use engine coolant to create heat.

Engine coolant stops the engine from overheating by absorbing heat. This causes the coolant to reach very high temperatures. The heater core allows engine coolant to flow through it, where the blower motor blows air through the heater core. As the air passes through the heater core, its temperature increases, allowing it to warm up the car’s interior.

The amount of coolant entering the heater core is controlled by the heater control valve. This valve opens and closes depending on what temperature the heater is set to, allowing for an increase or decrease in temperature. The heater control valve can either be controlled automatically in the case of a climate control system, or manually in the case of a standard cable control manual system.

Learn more about how car heaters work >


What causes car heater problems?

Low coolant – If your car has a coolant leak, the heater may not work due to an insufficient amount of coolant entering the heater core. A coolant leak can be dangerous because it can cause your engine to overheat. In this case, keep an eye on your temperature gauge and avoid driving if it gets too high. Learn more about diagnosing cooling system problems >

Thermostat stuck open – The thermostat opens and closes to let coolant into your engine. If it becomes stuck open, too much coolant will enter your engine, reducing the amount of heat the engine is able to generate. This symptom will often be accompanied by a loss of engine power. If your cars temperature gauge is not at half way within about 5 minutes of normal driving, then you may have a stuck open engine thermostat. In this situation you will find your heater feels colder than it should for longer.

Blower fan not working – The fan that blows air into your car’s interior may not be working. This can be caused by either a blown fuse, relay or switch or problems in the motor itself.

Heater core blockage – The tubes connected to your heater core can become blocked, limiting the flow of coolant. A heater core flush or a new heater core will fix this problem.


How important is a car heater repair?

A healthy level of coolant

If your malfunctioning heater is caused by a coolant leak, you should take your vehicle to a mechanic as soon as possible. A coolant leak can cause your engine to overheat, resulting in very expensive repair work if left untreated. A coolant leak often shows the following symptoms:

  • High temperature gauge
  • Puddles of coolant around the car
  • Heater blowing cold air
  • Low/empty coolant tank on inspection (always let the car cool down before removing the radiator cap)


Car Heater/Cooling System Repair in Hamilton

At Grimmer Motors, our quality mechanics can diagnose and fix all problems related to your car’s heater. If you suspect that your car has a coolant leak, we can also find and repair the leak, allowing your vehicle to run without the risk of overheating.

For reliable, high-quality heater repair in Hamilton, contact Grimmer Motors today!

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