Car Heater Blowing Cold Air: Causes and Cost to Fix

If you’re driving in the middle of winter and your car heater isn’t doing what it should, you could be in a terrible situation. Whether you’re dealing with freezing temperatures or not, it can be frustrating to deal with a malfunctioning heater. There are all sorts of causes, many of which are relatively cheap to fix.

So, do you know why your car heater is blowing cold air? It could be due to one or more of the following issues:

  • Dirty filter
  • Broken thermometer
  • Air locked in the cooling system
  • Plugged heating cores
  • Coolant misplacement

Throughout this article, you’ll learn the causes and methods of repairing a car heat that’s blowing cold air when it shouldn’t be. You’ll also know when you should get it fixed and whether or not it’s something to worry about.

Why is car heater blowing cold air.

What Causes Your Car Heater to Blow Cold Air

When you’re ready to turn on the heater in your car, the last thing it should do is make everything colder. Even if it’s putting out room temperature air, that’s not enough to perform the function that it’s designed for. The good news is that you can break it down in five different possibilities.

Here are the various reasons that your car heater could be blowing cold air:

  • A dirty air filter can cause all sorts of problems, including cold air coming from the heater. When there’s too much dust and debris caught in the filter, the warm air builds up inside and doesn’t penetrate through the vents. You’ll be left with air that’s 10 to 20 degrees less than it should be.
  • A broken thermometer is another common issue that causes cold air or warm air to come from the vents when it shouldn’t. When your car isn’t sure if you want it to go up or down due to malfunctioning parts, it won’t be able to properly meet your demands. You can turn the heater up and it still won’t increase.
  • Air locked inside of the cooling system can be a quick fix. If air’s locked anywhere in your car’s recirculation, it can prevent the correct temperature from flowing through. You’ll be stuck with whatever temperature air is in there, which usually cools down over time. Unfortunately, it’s a burden when it’s freezing outside.
  • Plugged heating cores cause issues just as a clogged filter does. If your heater isn’t allowed to heat up due to a clog, you’ll never be able to experience the primary purpose of it! Clogs can form from dust and debris, especially if you live in an area with sandstorms, dust devils, or high salinity in the air.
  • Coolant misplacement refers to the coolant not properly circulating through the system. This can be a result of a broken reservoir, but it also ruins the radiator in the long run. If you don’t fix the problem soon, it could end up costing you much more money. The temperature will properly work once you’ve repaired the system.

How Much Does It Cost to Fix a Car Heater Blowing Cold Air?

If you want the best prices for your vehicle repairs, you should consider fixing them yourself. Some people are more mechanically inclined than others, so there’s no shame in hiring a professional. It’s also nice to be able to get a warranty if you have someone else repair or replace a part in your car.

However, the prices for parts and labor can vary drastically. Before you settle for a quote, try to call around and get quotes from numerous shops in the area. You never know if there are going to be sales or flat rates that are much better than others.

Here are a few price expectations to fix the heater from blowing cold air:

  • A clogged filter usually costs about $75 to repair, but the parts are about $35. This slight differential might be enough to make you consider doing the repair yourself, especially since air filters are one of the easiest fixes on a vehicle.
  • Parts and labor to replace a broken thermometer in a car add up to about $200. Labor is half of the cost, and parts make up for the other half. All in all, you can save yourself 50% by doing a DIY job, but you have to deal with repairs if you botch the task.
  • Air locked in your car’s cooling system is one of the easiest fixed around, and it costs nothing if you do it yourself. You can repair this problem by elevating the car at an angle to release air bubbles, bleeding the radiator if your car has a valve, or starting the engine without the radiator cap on (only do this for 10 to 20 seconds).
  • Replacing a heating core is one of the most expensive repairs due to labor costs. While a heating core can cost as low as $80, the repairs can cost as much as $700 per core. Again, this depends on the make and model of your car, as well as the mechanic who’s doing the repair.
  • Coolant misplacement can be caused by the aforementioned air bubbles stuck in the radiator, but it can also happen due to a leak or rupture in the system. Whether your radiator is cracked, the cap doesn’t have a proper seal, or one of the hoses is loose, you can fix this problem for less than $400 in most scenarios.

Should You Be Worried?

It’s never a good idea to worry or panic about a car problem. However, many of the issues listed above can expand to worse concerns if you don’t deal with them in a timely manner. For example, air bubbles in the radiator can slowly cause a buildup of pressure, forcing a hairline fracture along the face of it.

Another example of neglect is when you don’t fix your car’s air filter. They’re designed to keep you safe by filtering out bad contaminants in the air, which aren’t going to be removed without a replacement. Finally, a broken thermostat can be a huge concern if you can’t keep an eye on the engine’s temperature.

In short, you shouldn’t stress too much, but you should also make sure that you have the repairs on your to-do list. If you’re able to repair them by yourself, then you shouldn’t have an issue getting your heater back to blowing out warm air. On the other hand, neglecting the repairs could cause you to spend more money.

The worst problem of all would be a bad thermostat combined with a malfunctioning radiator. If your car starts to overheat and you aren’t able to read the gauge, you won’t know that there’s a problem until the vehicle is smoking. Always deal with small repairs before they compound and combine with others.


Your car’s heater isn’t meant to blow out cold air. If you notice that the temperature is less than it normally is, there’s definitely a problem. There’s no such thing as a heater that naturally lowers its own temperature, so you definitely have a small problem to deal with. Fortunately, you’re now well-equipped with the knowledge that you need to fix the issue.

To recap, here are a few bullet points to remember:

  • Clogs, leaks, bubbles, and broken thermostats can all cause cold air to come from a heater.
  • Repairs can range from $0.00 to $900, depending on the part that needs to be fixed.
  • Deal with all repairs as soon as you can to prevent the problem from getting worse or costing you more money.




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