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How to Fix Car Heater Blowing Cold Air

March 3, 2024 | Victor Lukasso

Once a car heater starts blowing cold air instead of hot air, there’s a problem with the car heating system.

A car heater primarily aims to introduce warmth (hot air) into the car when the air conditioner presents excess cold. Also, the air conditioner helps make the cabin chill out and prevents excess heat.

If one of these systems works interchangeably or fails at any point while driving, the driver (and passenger) would experience extreme discomfort.

Your vehicle can also blow cold air while idling when stopped or intermittently.


The problem is likely caused by a faulty cooling system, a low engine coolant level, a defective thermostat, and others discussed below.

Additionally, a car heater blowing cold air can be fixed by refilling the coolant, replacing the thermostat, or getting a new heater control.

In this article, I’ll show you possible reasons why your car heater is blowing cold air and how to fix it.

Why is My Car Heater Blowing Cold Air

A car heater blowing cold air Is a minor issue since it is easy to diagnose and repair.

For those who don’t know, here are possible reasons why your car heater is blowing cold air instead.

1. Low Engine Coolant Level

Aside from keeping the engine running at a stable temperature, coolants are also crucial for properly functioning the car heating system. Once the coolant goes below the required level, the heater will start blowing cold air because it’s committed to making the engine function at that point until the next coolant refill is done.

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2. A Problematic Thermostat

A thermostat helps the car engine reach and maintain a standard working temperature as soon as possible. Your car heater will blow cold without the engine attaining that recommended temperature.

3. Air in the Heating System

If air gets into the heating system due to component(s) damage, your car heater might blow cold due to the leakage.

4. Damaged heater control

Since buttons and controls control these components, it may be possible that the heater control is faulty and needs repair or replacement. Also, it could be that the button is frozen, making you think that the car heater isn’t functional.

5. Spoilt Heater Flaps

The heater flaps regulate hot and cold air inflow into the vehicle. Any damage to these heater flaps will turn the check engine light on until a replacement is done.

6. Bad Heater Core

The heater core controls the car’s heating system, and as such, any defects that occur to it will affect the overall functioning of the heating system.

Car Heater Blowing Cold Air – FIX

We’ve seen the possible reasons why a vehicle heater will blow cold air; let’s see how to Fix the cooling system issue.

1. Refill the Coolant

When the heater blows cold air, you must first check the coolant level.

  1. Once you’ve purchased a quality coolant from Amazon, please park your car and leave it to cool off.
  2. Raise the hood of your car and open the radiator cap to check its level, the same with the reservoir tank.
  3. You can now fill the coolant in the radiator to the brim while ensuring the reservoir tank is filled according to the manufacturer’s recommendation using the MIN and MAX lines.
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Also, ensure not to overfill or overfill any of these vessels to avoid engine troubles.

2. Heater Control Replacement

If you notice that the fault is from your heater control, you can seek an auto engineer’s service to fix it.

You can also purchase a heater control from Amazon and follow YouTube guides to fix it yourself.

3. Replace problematic thermostat

After testing and diagnosing the fault in your thermostat, you can initiate a replacement.

4. Remove the blockage in the Heater core

You can visually inspect the heater core to identify if the problem is from dirt accumulation on the pipes. You can clean off the blockage by cleaning the outside of the heater, flushing the heater pipes, or manually removing dirt particles.

If the issue persists after the above troubleshooting, you should buy a new heater core.

5. Heater Flaps Replacement

Also, inspect the heater flaps or blend doors and perform a replacement if possible.

6. Bleed the cooling system

Bleeding the cooling system will eliminate trapped dirt, airlocks, or other foreign material. The bleeding process could be pretty tedious for newbies, but it’s worth it; nonetheless, you can seek the attention of a car heating service and repair

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7. Use the Windows

If you can’t implement any of the above fixes, you should consider winding up the windows while driving to prevent air from coming in, thereby releasing heat into the car.

Do this while the Air conditioner is turned off, though.

Car Heater Blowing Cold Air Cost To Fix

It’s pretty hard to determine what could be why a car heater is malfunctioning due to the various causes, but we’ll put the repair cost at an estimate of $10 to $1,000. It might cost more depending on the model.


Can I Heat My Car Without a Heater?

Yes, other economical ways can heat your car, but you can’t compare their efficiency to that of a car heater. You can adapt blankets instead of car heaters, wind up windows significantly when idle, or heat seats.


A car heater blowing cold air Is a minor issue, but at the same time, it could cause discomfort to car owners, especially those who frequently make use of the heating system.

In this article, I’ve outlined all the possible reasons why a car heater will blow cold and ways to fix them.

However, if you’re inexperienced and can’t fix your car using the above guide, it’s advisable to call the attention of a mechanic.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.