Why does my car heater go hot and cold?

Why does my car heater go hot and cold?

Most of the reasons a car heater blows cold have to do with the heater core. Still, you can also have a mechanical, electrical, or vacuum problem. The specifics vary significantly from one vehicle to another, but most systems have a blend door that changes how air flows or doesn’t flow through the heater core.

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

Problems with the vehicle’s heating system can be either no air or only cold air coming out of the heating system. A car heating system blowing cold air can be due to a faulty thermostat, low coolant fluid level, malfunctioning heater core, a leaking cooling system, or problems with heating controls and blend door.

Why is my heater not heating?

Dirty filters are the most common cause of furnace problems. Dust and dirt restrict airflow—and if the filter gets too clogged, the heat exchanger will overheat and shut off too quickly, and your house won’t warm up. If the blower is running but no heat is coming out, replace the filter.

Why would a car heater blow cool air?

One of the most common causes of a car heater blowing cold air is from low coolant. As stated before, coolant is what warms the heater core – if the coolant is low, there may not be enough heat transfer from the heater core to the air to heat the passenger compartment.

Why does my car heater blow cold air?

When Your Car Heater Blows Cold Air Quick Crash Course in Car Heater Operation. First off, everything here applies to vehicles with water-cooled engines. Car Heater Blowing Cold Due to Cooling System Issue. Stuck thermostat. Stuck Thermostats. Air in the Cooling System. Plugged Heater Core. Coolant Not Flowing Through the Heater Core. Other Reasons a Car Heater Can Blow Cold.

Why is my car heat not hot?

If the heater control valve is the culprit, the air coming into your vehicle won’t feel warm. The heater core may also leak coolant. The heater core is clogged from debris in the cooling system. If debris has caused a clog in the heater core, it will need to be replaced.