What Causes Car Heater To Blow Cold Air? 7 Surprising Issues!

Are you wondering what causes car heater to blow cold air? You should feel comfortable during your morning drive, and the car heater should not ruin it by not blowing warm air on a cold day. 

Be aware that this is a common car problem that most drivers experience. Although expected, it will be very frustrating to sit inside your freezing car during winter. 

what causes car heater to blow cold air

A couple of basic issues can cause the car heater to blow cool air. We will discuss each of them below and the most practical solutions to solve them. Keep reading!


How Does A Car Heater Work?

Many cars are designed with water-cooled engines. It works the same way as its heating system. The hot coolant coming from the machine will pass towards the heater core that functions and look like a tiny radiator. Air is being forced through it by the blower motor. Then, the air will become hot due to the coolant, and the car interior will then be provided with warm air. For this reason, it takes time before the heater can blow warm air, and any issue with those parts can cause the heater to blow cool air. 


7 Common Issues That Causes Car Heater To Blow Cold Air

The main issues that cause your car heater to blow cold air include a stuck thermostat, clogged heater core, stand in your cooling system, or if the coolant does not flow towards your heater core. In practice, it is more complicated than this, but those are among the most common issues that you may be experiencing. Let us discuss each of them below, along with some other cases and what you can do about them. So, what causes car heater to blow cold air? Here are the following:


#1. Low level of coolant

The coolant inside the engine, a combination of antifreeze and water, prevents overheating. The heat that supports the car heating system is sourced from. A low level of coolant in the system will cause the heater to blow cool air towards the cabin. After you have confirmed that the issue is due to the insufficiency of the coolant, what you need to do is to top it off. Also, check if there is a leak, especially when you have recently refilled it. 


#2. Heater core issue

The heating core is the cooling system that looks like a compact radiator. It is composed of metal tubes carrying the hot coolant inside and out. It also has a fan dispersing the heat that coolant released. If you notice the overheating of the engine, sweet smell, fog inside the cabin, or if the car used up its coolant quickly, then the heater core may be clogged. You will need to flush out the passage to solve the clogging issue. The heater core can be cleaned manually by removing the dirt and debris clogging it. But in some instances, an installation of a new one may be necessary to solve the issue. 


#3. The thermostat does not work

If your thermostat does not indicate that the car engine has already heated up, then it may be broken. In such a case, the coolant will not be sent so that the core won’t receive the heat it needs to blow warm air. For your heater to work, you need to install another thermostat. 


#4. Bad blend door

The culprit for the cold air may be the lousy blend door. If you do not know what a blend door is, it allows the air to get inside the vehicle from your heating system. But if it is blocked, it will not pass the heater core, thus providing cold air. If this is the case with your car heater, you have to replace your blend door. Most often than not, this issue is fixed when you have your water pump replaced or any other extensive repairs are done to your car. 


#5. Broken heating controls

For older cars, the heating control and buttons may become broken and clogged. In such a case, the different systems within your vehicle won’t communicate properly causing the car heater to blow cold air. 


#6. Water leaks

A car is a complex machine. Leakages may occur in many areas, leading to the malfunctioning of the other systems. If any of the water pumps, hose, or radiators will have leaks, then your heating system will not function correctly.


#7. Air in your cooling system

A problem may also occur when air ends up inside your cooling system. The highest point of a car’s cooling system is its heater core. When air moves towards it and becomes trapped there, you need to flush those air bubbles to solve the problem. 


It’s A Wrap!

Your car heater may fail in various ways. Suppose it is blowing cold air. In that case, the most probable causes are the blower motor not directing the air towards the core or the cooling is not flowing towards it. Most drivers typically deal with one of these issues. After knowing what causes car heater to blow cold air, fix it immediately and keep yourself insulated during winter. 

You may want to read related articles; know why is my car heater not working and how to make car heater warm up faster.

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