What causes the heater to not work in a car?

The heater switching system might be faulty. The cabin air filter might be choked, restricting the airflow through the heater core. The thermostat valve might not be working right. The heater core might be clogged.

Why is my car blowing cold air when the heat is on?

Low Coolant Level

The coolant (usually a mixture of water and antifreeze) in your engine doesn’t just work to keep the engine from overheating: It’s also the source of heat supporting the heating system. If there isn’t enough coolant in your system, the heater core will blow cold air into your car.

What could cause a heater in a car to stop working?

Causes of a breakdown

A heater can stop working for a number of reasons, including: A low antifreeze/water level in the radiator due to a leak in the cooling system. A bad thermostat that isn’t allowing the engine to properly warm up. A blower fan that isn’t working properly.

Why is cold air coming out of my vents when the heat is on?

Your Air Filter Is Dirty

Clogged air filters could be causing cold air to blow out of your vents. A dirty air filter can block airflow over your furnace’s heat exchanger, which can cause it to overheat.

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How do you tell if you have a clogged heater core?

Heater core failure symptoms

  1. Weak or no airflow.
  2. Cold air (not warm) coming through the vents when the heater is on.
  3. Coolant leakage visible inside the cabin or a damp smell.

Why is my car not blowing hot or cold air?

If your blower only works on the highest setting, your blower motor control module probably needs to be changed. If the fan isn’t working, you probably need to have the blower motor fixed or changed. If the air coming through isn’t hot, the heater core is probably clogged.

Will low coolant cause no heat?

Check the Coolant and Water Pump

First, check your coolant level to be sure there is enough liquid in there to even get to your heater core. If your radiator is very low on coolant, you’ll get no heat. If your levels are okay, you either have a bad water pump or a thermostat that isn’t opening.

Why is my heat and air not working in my car?

Faulty Thermostat

A faulty or broken thermostat is the most common cause of your car’s failing heat. Stuck open or stuck closed, the part can not only cause issues with your heat but also your engine’s cooling system. One becomes an issue of comfort, the other becomes an issue of “Oh no, I’ve borked my engine.”

Can a bad water pump cause no heat?

Yes, a bad water pump can cause no heat. This is because the water pump is what circulates the coolant through the engine and heater core. If it has failed, it is unable to pump the coolant properly, resulting in little to no coolant circulating through the vehicles heater core causing no heat.

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Why are some vents blowing cold air in car?

This situation can be caused by a bad blend door (also called air mix) actuator, a broken or binding blend/air mix door, broken linkage to the blend/air mix door, or a faulty HVAC control head or wiring harness.