Why does my heat cool down when I stop?

The function of the heater valves is to open and close to allow coolant to flow into the heater core. The valve remains closed blocking hot coolant in the cabin when the cabin temperature dial is set to cold.

Why does my heater only work when I'm driving?

Hello. When your vehicle is in motion and driving down the road, the temperature of the engine coolant tends to warm up in the engine before it reaches the radiator, so the heater will get hotter as you drive. Top up coolant if low.

What does it mean when the heater blows cold air into the car?

A car heating system blowing cold air can be due to a faulty thermostat, low coolant, a malfunctioning heater core, a leaking cooling system, or problems with the heating controls and the mixing door.

How do you test a heater control valve?

How to test a heater control valve. Adjust the heat to maximum with the engine at operating temperature. Next, check the hose temperature on the inlet and outlet sides of the heater control valve. The inlet and outlet hoses must have the same temperature.

What causes a malfunctioning heater control valve?

Coolant Leaks Over time, the heater control valve can wear and crack, causing coolant to leak out of the valve. Heater control valves can also leak due to excessive corrosion from contact with old or contaminated engine coolant.

Is it ok to avoid a heater core?

Driving with a faulty heater core can be risky as it can cause overheating and major engine damage. Avoiding the heater core is highly discouraged. Hot coolant won't flow through it when the heater knob is off, but coolant will still sit in the heater core and can still leak.

Will the car overheat if the heater core is bad?

If you have a bad heater core, you should take your car in for repair right away. Driving with a faulty heater core can be risky as it can cause overheating and major engine damage. Even a clogged heater core can prevent proper coolant circulation, causing the engine to overheat.