Like in many homes, a car’s heating system is linked to its cooling system. So, when a car heater is not working, you need to look at your vehicle's entire HVAC (heating, ventilation, and air conditioning) system.
Let’s look at this in more detail. The coolant travels around the engine to control the temperature in your car and makes its way back to the radiator. Here, the coolant’s temperature is reduced and passes back to the engine again. The hot coolant circulates to the heater core as part of this cycle. At this point, a blower motor is engaged, and warm air passes into the cabin. The climate control system manages the entire process; it regulates interior temperature and how fast the warm air is fed through the ducts.
Why Is My Heat Not Working In My Car?
Check out the typical trouble areas of a car’s heating system.
Low Coolant Level
A low coolant level can be caused by not keeping the system topped off or from leaks. It’s the first thing to check if you’re not getting heat in the car. Every time you check engine oil, eyeball the coolant level. The owner’s manual will tell you how to do this if you’re unsure. A coolant puddle on the car is a sign of a leak; have this checked out immediately. Also, coolant is highly toxic to pets (and humans, too), so keep Fido and Felix away from this fluid.
The thermostat is a valve that manages the temperature of the coolant that flows around the engine. As the engine heats up, the thermostat opens to permit the fluid to travel from the radiator to the engine. If it’s stuck in the open position, the coolant won’t heat up, and the heating system won’t be able to push warm air into the cabin. If the thermostat doesn’t open, you’ll see an engine overheating problem arise. In most cases, a thermostat repair is easy and relatively inexpensive.
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Defective Heater Fan
Your engine may generate plenty of heat, but if that heat can’t be pushed into the cabin, you and your passengers won’t get warm and toasty on a cold day. In this situation, we’re looking at a faulty heater fan. The fan itself may need to be repaired or replaced (most of the time, we’re talking replacement), or you may be dealing with a blown fuse.
Faulty Heater Core
Think of a heater core as a mini version of the radiator connected to the engine. However, while a regular radiator draws heat from the engine, a heater core collects the heat for distribution back into the car. A heater core will mix in the fresh air as part of the process. If your vehicle has dual-zone climate control, you’ll have a split heater core (one-half for each side of the cabin). Debris from a rusting radiator can collect and clog this component. Depending on the complexity and location of the core, this can be a pricey repair job.
Your car may have simple knobs or an elaborate touchscreen to manage your car’s HVAC system. Regardless of the setup, a bad control can mean no heat in the vehicle. This means something as simple as a replacement part or as frustrating as diagnosing a malfunctioning touchscreen.
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Air bubbles in the radiator can prevent the proper flow of coolant and affect the heating system (and the engine itself). This situation can happen if someone opens the radiator or if a leak allows air to enter; the system needs to be bled. Also, a bad head gasket can cause air to enter the radiator. If air bubbles are present, just hope it’s not due to the head gasket.
Blown Fuse / Bad Wiring
Anything in the heating system, like the fan or controls, that relies on electricity to operate may be affected by something within the circuitry. You might just be dealing with a blown fuse that’s easy and cheap to replace. At the same, a short in a wire could be causing the problem. In other words, don’t assume it’s a bad component when the electrical pathway could be to blame.
Preventative Maintenance Steps And First-Step Fixes
A few easy tasks can go a long way in helping to prevent and diagnose car troubles, like when a car heater is not working. Follow these steps.
- Just as you should be checking the oil level, ensure the coolant is full as well. This not only helps the heating system but prolongs engine life. Always review the car’s owner's manual for the correct steps to check the coolant level, and NEVER open a hot cooling system (boiling coolant can spray onto you).
- Dirty and debris-filled coolants can impact heating and cooling, too. So, check that this fluid is clean. Follow the manufacturer’s recommendation for coolant replacement and radiator maintenance.
- Checking the thermostat can also identify if there’s a problem with the heating system. Most car thermostats are located inside the housing where the engine meets the radiator hose. Removing the thermostat is simple if you’re handy under the hood. Immerse the thermostat in water at the correct temperature for your car and see if it opens. If not, you know the source of the problem. Again, never open up your coolant system while it’s hot. If you're uncertain about what to do or have any hesitation working under
- Your routine maintenance should include a check of belts and hoses, many of which are required by the coolant system. Regular inspection of these components can prevent an HVAC issue before it starts.
Final Thoughts On “My Car Heater Is Not Working”
The good news is that problems with the heating system are rare if you have a newer car. Engineering and modern technology have eliminated many trouble spots that plagued vehicles from earlier eras. Stay alert for the warning signs if your car is from the 20th century. Regardless of your car’s year, keeping a well-maintained cooling system is the most important thing you can do to avoid heating issues.