The car heater is one of the most important parts of your car. The main function of the car heater is to supply hot air to the car cabin. Therefore, proper repair and maintenance of the heater are very important to ensure its efficient performance.
Is your car heater blowing cold air? Don’t worry; this article explains the reasons why a car heater blows cold air and how to fix it.
A heater core is used to heat the passenger compartment of a car. The heater uses a coolant as a working fluid.
The hot coolant flows through the coiled tubing of the core. This coolant acts as a heat exchanger between the cabin air and the coolant. Fins attached to the core tube increase surface area and help the fan transfer heat to the air flowing through the core tube, heating the interior cabin.
Causes Why a Car Heater Blowing Cold Air?
Your car heater usually blows cold air due to one or more of the below-given reasons:
- Insufficient Coolant
- Bad Thermostat
- Coolant Leak
- Defective Heater Cores
- Jammed Blend Door
- Damaged or Broken Blower Motor Resistor
- Water Leaks
- Blown Fuse or Faulty Wiring
1) Insufficient Coolant
The engine coolant is a mixture of antifreeze and water. The engine coolant is very important for the proper operation of the engine. It prevents the engine from overheating. It also acts as a heat source that supports the heating system.
When the system does not have sufficient coolant, the car heater doesn’t produce sufficient heat, and the heater core blows cold air into the car.
Solution: As you observe that your heater is not working properly due to the insufficient amount of coolant, simply add more coolant up to the desired level.
2) Bad Thermostat
Is the thermostat still at “C” after the engine has warmed up? In this case, your thermostat may be defective. A thermostat acts as a valve that closes and opens for the coolant. It regulates the coolant supply to the system.
A defective thermostat can’t properly send a signal that the engine is warming up. In such a condition, the coolant will not properly absorb the engine heat and will not properly heat the heater core air, and your heater core will blow cold air.
Solution: As you observe a defective thermostat, immediately buy a new thermostat and install it for the proper working of the heater.
3) Defective Heater Cores
The heater core plays a big role in heating the car compartment. It consists of multiple metal tubes. It takes hot coolant from the cooling system of your engine and passes it through different small tubes.
When the hot coolant passes by the metal tubes, it transfers its heat to these tubes, which in turn warms the air passing through the heater core. This hot air is then transferred to the car compartment through the vents, providing warmth to the passengers.
If the heater cores have been clogged or damaged, you may see the following symptoms:
- Mist in the cabin of the car
- Sweet smell
- The car quickly runs out of coolant
- Engine overheating
Solution: You can manually clean the outside of the clogged heater cores, flush the duct of the clogged heater core and remove contamination that blocks it. In severe conditions, you must replace your heater cores.
4) Coolant Leak
The coolant leak is one of the common reasons due to why your car heater blows cold air. The shortage of coolant causes the engine to overheat. This problem may also lead to the complete failure of your engine.
Solution: Check the coolant leak as you refill your coolant into your car radiator. If there is a leak, immediately drive your vehicle to a technician and ask him to fix it.
Read More: Signs of Coolant Leak
5) Jammed Blend Door
The blend door permits air to enter from the heater to your car compartment. As your car blend door James, air bypasses the heater core, leaving a heater that only blows out cold air.
Solution: You should immediately replace the faulty blend door. The jammed mixture is often resolved with other major repairs, such as replacing the water pump.
6) Broken Blower Motor Resistor
The blower motor resistor is used to control the speed of the blower motor fan.
The blower motor fan of your vehicle has the responsibility to move air through the car’s vents to deliver hot or cold air to the car cabin. The blower motor resistor operates by regulating the electrical current that is transferred to the blower motor fan. It performs this work by using a series of resistors.
A bad blower motor resistor can prevent you from adjusting the appropriate fan speed. When your blower motor resistor works properly, you can easily adjust the speed of the blower motor fan using the vehicle’s heating and cooling controls.
Solution: If your blower motor resistor is bad, you need to replace it.
7) Water Leaks
Water leakage is the most common issue with the heating system. Leaks can occur from various locations such as a water pump, radiator, or hoses. If one of these three components is leaking, the car heater can’t work efficiently. Therefore, properly check the water pump, radiator, and hoses before driving.
It is important to fix the car heater problem immediately. Ignoring the problem can lead to bigger and more expensive problems or repairs in the future.
Solution: If you notice water leaks or if your system is unable to dissipate heat from the vents, contact your local technician to fix the issue.
8) Blown Fuse or Faulty Wiring
Just like a bad HVAC control, the car’s wiring may also damage or short out. In this case, if the driver commands the heater to run, the heater will not work.
Solution: As you observe that the wiring of your heater is faulty, contact the technician and ask him for the proper operation of your car heater. If you have blown a fuse, replace it with a new one.
Read More: Types of Engines
How to fix a car heater blowing cold air?
One or more below-given repairs can fix the car heater that’s blowing cold air:
- Adding more coolant if needed
- Fixing the coolant leaks
- Replacing the bad thermostat
- Replacing or repairing the faulty heater cores
- Replacing or repairing the jammed blend door
- Replacing the faulty blower motor resistor
- Fixing the water leaks
- Replacing the blown fuse
- Replacing or repairing the damaged wiring
- Replacing the faulty water pump or radiator
Heater Core Replacement Cost
The new heater core replacement cost depends on many factors such as labor cost, vehicle model, and type of brand. The average replacement cost of the heater core is from $450 to $1100. This cost includes the labor cost and parts cost.
Some vehicles use expansive heater cores. Therefore, such heater cores have a minimum $1050 or higher replacement cost.
How much does it cost to fix a car heater blower?
The average replacement cost of a car heater blower motor is from $360 to $400. The cost of the new parts is from $270 to $285, while the labor cost is from $90 to $115.
| Parts Cost | $270 to $285 |
| Labor Cost | $90 to $115 |
| Total Cost | $360 to $400 |
Read More: Different types of IC Engines
FAQ Section
What is Heater Core?
The car heater is used to heat the passenger compartment of your car. The heater uses a coolant. The cold coolant gets heat from the engine, transfers that heat to the air, and the heater blows the hot air into the car compartment.
Why is my car heater not getting hot enough?
If your heater is not getting hot enough, it may be because of the cold engine. Turn on the engine and wait for a few minutes until the engine heats up.
If your heater is still not producing enough hot air, you may have a defective thermostat, heater core, insufficient coolant, or coolant leak. In these conditions, stop the car and inspect and repair the faulty part.
Why is my car heater blowing cold air?
The car heater can blow cold air because of different reasons. Most commonly, the car heater blows cold air because of the following reasons:
- Inappropriate working or a bad thermostat
- Broken blower motor resistor
- Insufficient supply of the coolant
- Coolant leak
- Defective heater Core
- Water leaks
- Jammed blend door
What are the Symptoms of a Bad Car Heater?
A bad car heater has the following signs:
- Blowing cold air
- Fog inside your car
- Engine overheating
- Low coolant level
- Non-existing or weak cabin heating
- Coolant smell inside the passenger compartment
How Much Does It Cost to Repair a Car Heater?
The repair cost of a car heater depends on many factors such as the type of repair and the area where you are and the labor cost. If you repair it yourself, you will just need to pay for the new parts. However, the average repair cost of the car heater is from $750 to $1100.
What are the parts of the Car Heater?
The car heater has the following major parts:
- Heater Core
- Reserve Tank
- Lower Hose
- Water Pump
- Transmission Cooler
- Fan
- Radiator
- Upper Hose
- Thermostat
- Pressure Cap
How much does a new Thermostat Cost?
The cost of the new thermostat depends on the brand type. If you are replacing the thermostat yourself, then the average cost of a new thermostat is up to $50.
Why my car heater blowing cold air but not overheating?
If your car’s heater is blowing cold air but the engine is not overheating, there are a few possible reasons for this:
- Insufficient coolant
- Heater core issues
- Faulty blower motor or resistor
- Faulty water pump
- Faulty blend door
- Coolant leaks