7 Reasons You Might Not Know: Why Is My Heat Blowing Cold Air In My Car? (Fixed)

“How to make car AC colder” or “Does AC use gas?” aren’t the only questions drivers often ask about the AC. “Why is my heat blowing cold air in my car?” is also common. Let’s admit it, no one can bear the cold air of the heater when it’s freezing outside!

There are many causes for the above phenomenon. In this post, Driverevolve will pinpoint the 7 most common ones and the best fixes for each scenario.

1. Not Enough Coolant

To keep your vehicle from overheating in cold weather, your automobile uses coolant (typically 50% antifreeze plus 50% water). When you turn on your heater in the wintertime, coolant flows from your motor to your heater core. Ultimately, the heater core will circulate the heated fluid throughout the automobile.

Until your motor starts up, the coolant won’t become hot enough to heat your cabin, so the first couple minutes of driving may be cold.

If cold air keeps blowing out after a while, examine your coolant level. If your vehicle’s coolant runs low, your heating unit won’t be able to generate warmth.

Low coolant levels often cause heating system problems. In this case, adding more coolant is in order.

Fill your tank with the recommended amount of coolant specified in the car’s handbook (also, see how to put coolant in car). If you still notice your coolant level falling even after refilling, this is a sure sign of coolant leakage.

To prevent additional harm to your vehicle, you should not hang around for too long. Have a professional check the car for leaks and fix any related broken parts.

2. Problems With Heater Core

When a vehicle’s heater isn’t working, it’s often due to issues with its heater core. Examples include a blockage inside your core’s tiny tubes, a leak in its coolant lines, or a problem with its blower fan.

In essence, heater cores are little radiators that function as part of an air conditioning unit. This component is usually located behind the dashboard. 

A heater core consists of blowers that distribute the heat emitted by liquid coolant and metal tubes that deliver coolant through and out. When it comes to preheating and warming up a car, the heater core pulls all the strings. 

If the coolant amount and condition are OK, yet the automobile fails to produce warm air for the interior, there might be a problem with your heater core. Look for the signs of a bad heater core to detect the problem faster.

In case the tube heading to your heater core gets blocked, you may clear it out by flushing the system. When the outside of a heater core is congested with trash or particles, manually remove them.

If you still have issues with your heating element after flushing your heater core tube and cleaning its outside, you may have to purchase a new heating core.

3. Broken Or Clogged Heater Controls

Why is my heat blowing cold air in my car? It might be because of your faulty heater controls or damaged control valves.

The switches on your controller might become clogged up and unresponsive after years of use. Likewise, degraded control valves may also explain your car blowing hot air.  

The control valves for your vehicle’s heater are located beneath the hood. They serve as the heating starter. If this part doesn’t work right, your car may no longer be able to circulate warm air into the cabin.

If the coolant amount is good and your heater core seems to function properly, you might have to change all the controls or your heater control valves.

4. Issues With Thermostats

Thermostats are devices that open and shut in response to changes in inlet temperatures. They remain closed when the motor heats up and won’t open until the coolant hits a specific temperature.

If they don’t open at that moment, your motor might burn up, and your heater could fail to operate appropriately and release cold air.

If your thermostat fails to close correctly, it may delay or stop your motor from reaching its optimal operating temperature. A locked open thermostat might be at blame if your heater produces chilly air instead of warm air.

After your motor has warmed up, if the thermostat monitor still reads “C,” you might experience a faulty thermostat.

Your vehicle’s air conditioner won’t work if its thermostat isn’t able to inform it when the motor is hot enough. In other words, your car won’t know when to send appropriately heated coolant to its heater core. 

Replacing a broken thermostat is a cheap and simple way to get your heating system up and running again in this case.

5. Water Leaks

Water leaks may happen anywhere, so it’s essential to inspect all pipes, heaters, and water pumps. Don’t expect your vehicle’s heater to function if any of these components are leaky.

Having a reliable heater may make the colder months much more bearable. If you experience any of the above leaks or if no warm air comes from the ducts, you should have a professional technician examine your heating element.

Fixing faulty vehicle heaters as soon as possible is crucial. Ignoring the signs may lead to a more severe and expensive-to-fix condition.

6. Air Bubbles In The Cooling System

Large air pockets within your coolant liquid might cause your heating unit to emit cold air. Without a smooth surface, your coolant cannot transmit heat effectively. If the coolant in your heater isn’t warm, the air coming out of your vents won’t be either.

Follow these steps to eliminate air pockets in your coolant:

• First, crank up the thermostat to its highest setting. After that, remove the coolant reservoir’s top and fill it to the recommended level.
• Then, turn the key while your fuel cap is still off and allow your engine to run for a few mins at idle. When your thermostat door opens, check the coolant amount and fill it up if necessary.
• Your coolant liquid should be completely free of air pockets at this stage. When the engine is at operating temperature, you may shut off your coolant reservoir and check the heater.

7. Faulty Blend Door 

Your heater core is usually at blame whenever the vehicle’s heater isn’t delivering warm air. There is still the possibility of a mechanical, electrical, or vacuum malfunction. 

Although the details differ significantly from car to car, most mechanisms possess a blend door that regulates whether or not air is allowed to pass through your heater core.

You may have a functional heater core, but it won’t help if your blend door is jammed. In that case, the heater core is completely shut off, and all that blows through the vents is freezing wind.

A blend door may get jammed for many reasons, and they don’t always provide the same effects. If it gets locked open, you receive full warmth all the time; if it gets jammed halfway closed, you get just partial heat.

Mechanical connection, a disconnected vacuum pipe, a faulty valve, or several other factors may contribute to a jammed blend door. 

Like the heater control buttons, a damaged blend door requires immediate replacement.

Wrapping Up 

Why is my heat blowing cold air in my car?

It might be a coolant issue, a defective heater core, a jammed control, a thermostat problem, a malfunctioning blend door, water leaks, a coolant’s air pockets, or some rare conditions.

Regardless, it’s best to talk to a professional to get a full diagnosis and advice on the best treatments. 

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