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Why is My Car Heater Blowing Cold Air?

You climb inside your car from the bitter cold and flip on the heater to warm up, but something is wrong: “Why is my car heater blowing cold air?” The problem usually stems from one of two things. Your problem could be anything from your coolant, to your heater core, to your thermostat. So, what should you do? Let’s go over your options with our expert service team at Jeffrey Nissan!

How Does a Heater in a Car Work?

While it may be surprising to hear, your heater is part of your car’s cooling system. So when your car or truck heater is blowing cold air, it’s an issue with your cooling system. But before you can know why your car heater is not working, you have to know how it works in the first place! Most vehicles have a water-cooled engine, which is cooled with the help of a circulated water and coolant mixture and a radiator. As your water pump circulates your water and coolant mixture through your engine, it is heated up by combustion. The heated water and coolant mix is pushed towards your radiator (typically located behind your grille), which uses incoming air to drop the temperature of your coolant.

However, before the hot coolant reaches your radiator, it travels through your heater core. Your heater core a smaller version of your radiator, and is typically located somewhere behind your dashboard. So when you turn your heat on, a fan blows air through your heater core, and the air is heated by your engine’s coolant. This air is filtered and then warms up your interior!

Car Heater Not Working? Common Cooling Issues Are to Blame!

So, you’re still left wondering, “why is my car heater is blowing cold air?” There are a few possible issues, and you’ll need to pinpoint the exact location of the problem if you want to enjoy a cozy cabin. Here are some common issues when your car heater is not working:

  • The thermostat may be stuck, causing the coolant to stay pooled in one area rather than circulating.
  • Air bubbles may have gotten trapped inside your heater core, which means it’s not getting warm enough to transfer heat.
  • Your cooling system might be plugged with corrosion or debris, which prevents the coolant from flowing through it entirely.
  • The vent that directs hot air into your cabin could be blocked, preventing the air from making it to your interior.
  • Coolant level is too low, so the heater core is not getting warm enough to transfer heat.

Troubleshooting a Car Heater Blowing Cold Air

If you’re the DIY-type, there are a few steps you can take to why your car heater is not working. Take a look at these common tips to check on your why your car heater is blowing cold:

  • Check your coolant! If your coolant is low or discolored, replacing it or topping it off could show improvement
  • Keep an eye on engine temperature. If your coolant level is a-okay, but your car heater is blowing cold air and your engine is overheating, then you have a clog in your cooling system. Conversely, if your engine temperatures are unrealistically low after a drive, your thermostat is likely the culprit.

Car Heater Not Working on Electric, Hybrid, or Vintage Car

Some vintage vehicles use air-cooled engines, and newer hybrid or plug-in models may use electrical heaters. If you don’t know what kind of heater you have, be sure to consult your owner’s manual or just head to our service department for expert advice. So, what about vehicles that don’t use a water-cooled heating system? If you have an air-cooled or electrical system, then the issue may be a little more complicated. It’s worth a visit to the dealership to sort out the problem. Your battery and alternator may not be getting the power that it needs to fully heat up, or a component may be broken inside your HVAC system. Those with plug-in or hybrid models that notice, “my car heater is blowing cold air!” should contact us for help on pinpointing the issue.