Hey, Why is My Car's Heater Not Working?
Your vehicle's cooling system is responsible for the heat that is generated inside the vehicle. The cooling system has several components that maintain proper engine temperature to provide for proper combustion and low emissions from the exhaust pipe. The secondary by-product of this cooling system is to transfer the heat from the coolant to the inside of the vehicle through a heater core. Once the coolant is transferred through the heater core, climate control blends air to maintain the proper temperature inside the vehicle.
Is The Heater in Your Car Not Working?
The heater isn't working because of issues with the blower motor. This can be caused by internal damage or wiring problems preventing power from getting to the blower motor. However, in less common cases, the issue might be related to something different, like a restricted heater core, faulty blend door actuator, faulty coolant control valve, or a stuck-open thermostat.
A car heater not working can involve several different car systems! Ignoring heating problems can jeopardize your comfort, create further issues, and drain your wallet.
Consider consulting a skilled expert who can pinpoint and recommend future actions to prevent and fix the problem. This keeps your vehicle running smoothly, allowing you to enjoy a cozy ride worry-free. Remember, if left unattended, a minor glitch can snowball into a major headache.
Let's Get To The Bottom Of It!
The heater core has a passage where a liquid called engine coolant flows through it. A blower motor pushes air across the heater core's fins to heat the air. This air absorbs heat from the coolant, warming it before entering your car's interior. However, if the heater core gets clogged over time due to a lack of maintenance, it restricts the coolant flow. This reduced flow means less heat is transferred to the air, and that's why you might get lukewarm air from the heater. In rare cases, the heater might also blow cold air, emit a sweet smell, or clicking noises.
Inside your car's dashboard, there's a "blend door" that controls the heater's temperature. It makes the air colder or hotter, depending on what command it gets. This door moves because of a little motor called the "blend door actuator," but its gears can wear out over time, causing problems. You might notice temperature issues and hear clicking noises when adjusting the temperature. In rare cases, the "check engine" light also lights up on the dashboard, and the heater blows weak air.
The blower motor in your car's heater is like a fan that pushes air across. Over time, this motor can wear out and draw more electrical current. When this happens, the wires and connectors can get hot and melt, leading to a weak and intermittent connection. As a result, the blower motor may work sometimes but not always. More rarely, this can trigger the "check engine" light on the dashboard.
Certain vehicles have a valve called the "heater hose control valve." Its job is to restrict the amount of hot coolant that goes into the heater core, which helps improve the effectiveness of the air conditioning system. This valve can operate in different ways: mechanically, by vacuum, or electronically. If this control valve malfunctions, it restricts the hot coolant flow to the heater core. As a result, even after the engine warms up, you won't get any hot air from the heater vents. In rare cases, this might accompany a coolant leak, weak airflow from the vents, and clicking noise under the dashboard.
Inside your car's heating and air conditioning system, there's the "airbox." It has plastic doors that control the airflow to manage the temperature. These doors are moved by small motors called "door actuators." If these doors break, the actuator can't control them anymore and gets stuck in one position. Since the doors blend hot and cold air, the temperature won't change, no matter what you set on the control panel. This rarely accompanies a "check engine" light on the dashboard.
The thermostat in your car helps the engine warm up in a calculated time to reduce emissions. But it can get stuck open and break down after wear and tear. When the thermostat sticks open, the engine takes longer to reach its ideal temperature. This warm-up delay is alarming to the engine computer, activating the "check engine" light on the dashboard.
Find Professional Help
Vehicle Health Inspection Proof
Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.
- Restricted Heater Core
- Faulty Blend Door Actuator
- Faulty Blower Motor Wiring/Connectors
- Faulty Coolant Control Valve
- Broken Blend Door
- Thermostat Unable to Close
This proof image confirms the restricted flow in the heater core, which is causing the heating problem in the vehicle.
When the customer brought in their vehicle, they mentioned that the heater only worked while driving at freeway speeds. The heater's temperature wouldn't act right if they drove at normal speeds.
The technician confirmed the heater was blowing ambient air during the test drive. So, it wasn't working as expected.
To diagnose the issue further, the technician conducted a vehicle health inspection. During this inspection, they didn't find any immediate problems related to the customer's concern.
However, to investigate the heating problem, the customer authorized additional diagnostics. Then, the technician used an infrared digital thermometer to read the temperature of specific car parts. They started the engine and measured the temperature at the upper radiator hose, which was 198ºF.
Then, they checked the temperature of the heater hose going into the heater, which was 199ºF. However, the temperature coming out of the heater core was only 85°F. This temperature difference means the heater core was restricted, reducing coolant flow.
Based on the findings, the technician suggests trying a process called back-flushing the heater core to see if it helps restore proper coolant flow. They recommend replacing the clogged heater core if this attempt doesn't work.
1/6Typical Fixes to Address the Cause(s)
The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.
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Vehicle Symptoms
Below are just a few examples of typical Symptoms and Fixes your car might be experiencing
Other things your auto repair shop might talk about:
Heater control valve. Cooling system. Cabin air filter. Coolant level. Radiator cap.