Car A/C Heater is not working

During winters, depending on where you live, the heater in your car becomes a vital component you rely on, and need it to work whenever you turn it on.

How this system works:

A car’s heating system is very similar to its cooling system. In the latter, coolant circulates through the engine, absorbs heat, and dispels it into the outside air by way of the radiator. In the case of the heater, the same piping hot coolant runs through the engine, but is funneled through a much smaller radiator called the heater core. Instead of venting the heat outside the car, a blower fan pushes the warm air created by the heater core through air ducts and into the vehicle.

A heater that’s working properly should circulate hot air. If it doesn’t, there is a problem within the system.

Common reasons for this to happen:

There are a number of reasons why the heater might not be working properly. Here are the most common ones:

  • Low coolant in the radiator

Keep in mind that the warm air that rushes into your car is the byproduct of the heat of the coolant in your vehicle’s engine. If that coolant is low or contaminated, you have a problem. Although a leaky or weak radiator cap might be to blame, it’s more likely there is a leak somewhere in the coolant system. Coolant doesn’t evaporate on its own.

  • Blown fuse

The main job of a fuse is to protect the electrical circuits in your car from shorting or overloading; i.e., a fuse protects the wire or wires they are connected to from overheating and catching fire. Fuses are rated by their amperage and are designed to blow or open when the current being drawn through them exceeds their design rating. If a device draws enough current to blow a fuse, you’ve probably got a problem somewhere else in the system that will cause the fuse to blow again, sooner or later. Rarely do fuses fail for no apparent reason.

  • Air pockets in the heater core or a heater hose

This is another common culprit, and may be interfering with the flow of coolant through the heater core. Typically if you have air in the cooling system, then you have a leak that’s allowing coolant to escape and air to take its place.

  • Faulty water pump or serpentine belt

The water pump keeps the coolant circulating throughout your engine. Water pumps are belt-driven, and belts have a tendency to break and wear.

  • Malfunctioning thermostat

The job of a thermostat is to regulate the flow of coolant. By doing so, it lets the engine warm up as quickly as possible, thus reducing engine wear, deposits and emissions. When the engine is cold, the thermostat doesn’t allow coolant to flow through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens, and the fluid starts flowing. When the thermostat is worn out, it remains stuck in the open or shut position, which leads to either overheating or cool operation, respectively.

  • Clogged heater core

Debris in the cooling system, such as rust particles or other goop, can potentially plug the heater core and block the flow of coolant.

  • Malfunctioning blower motor

Any fan can go bad, and it’s a fairly easy replacement procedure. Before doing so, however, the mechanic will check the resistor, motor and fuse for proper operation. Failure of any of these components may result in the same symptom.