Baby, It's Cold Inside! How to Diagnose Car Heater Issues

January 7, 2022

Brrr. Is it getting cold in here? Your car heater does everything from helping warm up your cabin to defrosting the windows, and when it doesn't work as it should, it can make your drive uncomfortable and possibly even dangerous. Here's how you can diagnose and fix common heater issues to help keep the cold out this winter.

What Causes Your Car Heater to Stop Working?

Your vehicle's heating system is made up of many different components, and they each play important roles. When you start to experience your car heater not getting hot, there could be a few different culprits. Here are some common causes of car heater issues to keep an eye out for.

Broken Thermostat

Car heater problems are most often caused by a dysfunctional thermostat. Over time, your thermostat might wear out and become stuck in either an open or closed position. If your vents aren't blowing out hot air, this should be one of the first things you check. A thermostat that's stuck open can cause your engine (which is where your heater draws heat from) to stay too cool.

Malfunctioning Fan

The heater fan blows heat into your cabin. Every other part of your heating system can be working just fine, but without the fan, that hot air won't reach you. An electrical short or other damage could cause your fan to stop working correctly. If you don't hear the fan running when you turn the heater on, this is likely the root of your problem.

Low Coolant/Antifreeze Levels

When it comes to heat, coolant (also called antifreeze) probably isn't something that comes to mind. While coolant works to help keep your engine cool, it also plays a big role in your heating system. Coolant heats up when it's in the engine, and when you turn on the heater, this hot fluid is pulled into the heater core. The heater core then blows warm air into your cabin. This process can't take place if you don't have enough coolant. Luckily, this issue is easy to check and fix.

Issues with the Heater Core

Speaking of the heater core, it can also be a cause of your car heater not working properly. The heater core can get clogged with debris and contaminants, which can negatively impact its performance. If the heater core is to blame, you might notice your coolant level falling quickly, fog or a film on the inside of your windows, or a sweet smell in the cabin.

Failing Heater Controls

Depending on how old your vehicle is and how often you use the heater or A/C, the heater controls might stop working as they should. The knobs and buttons might become stuck or clogged with gunk, or they might not be connecting to your heating system. In some cases, you may only need to clean and wipe around the controls, but other issues may require more extensive repairs and replacements.

How to Fix Car Heater Problems

To fix a car heater, you first need to determine the source of the problem. Using the above causes as guidance, start with the most simple issues to check(like low coolant) and begin a process of elimination until you find the failing part behind your heater troubles. Once you've determined the cause of your car heater issues, you can order the appropriate replacement parts.

If something like low coolant or gunked-up controls is causing your heater not to work, you can likely fix the problem at home. However, more advanced issues like a broken heater core are probably best left to the professionals.

Find Quality Replacement Parts at Nissan Parts & Accessories

You don't need to suffer with a cold car cabin. Get your heater back in working condition with Genuine Nissan HVAC parts from Nissan Parts & Accessories. Order your replacement part online, and stop by your nearest authorized service center to let a trained technician handle the installation.