Why is My Car Heater Not Working?

As summer fades into the past and winter is on the horizon, you may start to notice your car’s heater doesn’t keep you as warm as it used to, or even warm at all! There’s probably nothing worse than hopping in your car on a cold morning and not being able to crank up the heat. What gives?

While it may seem like your car’s heater creates warmth out of thin air, there’s a relatively simple process behind the scenes that allows us to keep our vehicles at a comfortable temperature. 

How Does My Heater Work?

It may not come as a surprise, but engines are pretty good at creating heat (sometimes too good). This heat really comes as an unwanted byproduct of combustion, however, it serves a critical role in keeping us toasty during the most frigid of months. 

Your vehicle’s coolant is responsible for drawing that heat away from your engine to keep it at a healthy temperature. In most cases, the coolant is simply routed to the radiator so it can release this heat and loop back to the engine for further cooling. 

When your vehicle’s heater is in use though, the coolant gets to play a secondary role of delivering heat to our HVAC system. The hot coolant is directed to the heater core, where the heater fan then blows that heat into the cabin of the car’s interior. Afterward, the coolant is directed back into the cooling system.

You can essentially think of a heating system as just another radiator, but the heat is directed to the inside rather than the outside of the vehicle. 

What’s Wrong With My Heater?

While a relatively simple process, heating systems can still encounter several issues that can impact their performance, such as:

Low Coolant

As heater cores rely on coolant, a lack of it can heavily reduce heating performance or even stop it altogether. Whether the coolant has leaked out or burned off, there will be an insufficient amount of antifreeze to reach the heater core. 

Beyond just the heater, low coolant can cause considerable issues in the rest of your vehicle. Without proper antifreeze levels, your vehicle will be unable to regulate the temperature of your engine. This can lead to the heat reaching an unsustainable level and causing irreparable damage to your engine. 

You can check for an adequate coolant level but checking the coolant reservoir and ensuring it falls somewhere between the minimum and maximum line. Do not open your coolant reservoir cap before letting your vehicle completely cool down. Your vehicle’s cooling system is pressurized when hot, and will spew boiling antifreeze from the filler cap if not allowed to cool. 

coolant in car radiator

Broken Thermostat

Your vehicle’s thermostat is vital for controlling the flow of coolant. So you could imagine that it may cause some issues when your thermostat is not operating properly. Whether it’s stuck open or closed, your thermostat not being able to regulate coolant can lead to considerable problems with your heater. 

Similar to low coolant, it goes beyond just a comfort issue. Without the ability to manage the flow of antifreeze, your engine can experience catastrophic overheating. A faulty thermostat should be taken care of immediately by a trusted automotive professional to avoid critical damage. 

Electrical Issues

Not every problem with your heater has to be mechanical. Our vehicles are chock full of fuses, sensors, and wiring to control their various systems. Your HVAC system is no exception. Whether it’s a stripped wire causing a short, or a blown fuse disrupting the whole system, electrical problems can be some of the most difficult to diagnose. 

Clogged Heater Core

Over time, coolant can pick up debris and particulates. In some cases, this can begin to build up around the heater core and restrict or even completely block coolant from entering the heating core. Of course, this means that your heater will not have any warm air to direct into the cabin. 

This issue is generally less common than others and can be prevented with regular coolant flushes to ensure your cooling system isn’t contaminated. 

Faulty Heater Fan

The heater fan is one of the most essential components of the system. Without it, the hot air will never be blown into the cabin. While uncommon, these fans can fail over time and could be the source of your trouble. 

HVAC Service at Toledo Auto Care

Don’t let yourself freeze in this upcoming Ohio winter. If you’re looking for heater service in the Toledo or Whitehouse area, trust the experts at any Toledo Tire and Auto Care location for high-quality service. Call or schedule online with us today!