Often asked: Car Heater Blows Cold Air When Driving?

Why does my heat get cold when I drive?

Hot coolant from the engine passes through a heater core, which looks and functions a lot like a small radiator, and a blower motor forces air through it. It’s also the reason that a plugged heater core, stuck thermostat, or air in the cooling system can all cause a car’s heater to blow cold.

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

The Thermostat is Stuck While the engine is warming up, the thermostat stays closed. When the thermostat fails to open, it will restrict the air flow. If the thermostat won’t close, the coolant won’t be able to warm up enough, resulting in cool air blowing from your vents when you have it set on heat.

Why does my heater only work when my car is moving?

When your vehicle is in motion and driving down the road, then engine coolant temperature tends to get hotter on the engine before it gets to the radiator, so the heater will naturally heat up more when driving around.

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What do I do if my heater is blowing cold air?

When your furnace blows cold air, try turning the heating unit off and on. If the air feels warm for a moment or two, then switches to cold, it may be that the flame sensor is dirty. With a dirty flame sensor, your gas burner won’t stay lit, causing the air to go cold soon after the furnace turns on.

How do I know if my heater core is clogged?

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 heater not blowing hot air in my car?

Faulty Heater Core Faulty heater cores and low or contaminated coolant levels often come hand in hand, and both issues may lead to your engine overheating and your heater not blowing hot air.

How do you know if your thermostat is bad in your car?

Here are the signs your car thermostat is failing:

  1. The temperature gauge reads high and the engine overheats.
  2. The temperature changes erratically.
  3. The vehicle’s coolant leaks around the thermostat or under the vehicle.

How expensive is it to replace a heater core?

Replacing the heater core can be an expensive job, and usually costs between $564 – $927 for parts and labor. The parts aren’t particularly expensive, normally costing $80 – $234, but the location of the heater core means that labor costs tend to be quite high.

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How much does it cost to replace a thermostat on a car?

The cost of getting a thermostat replaced in a car is about $200 to $300 on average.

How do I know if my heater control valve is bad?

Here are some of the warning signs of a bad heater control valve:

  1. No heat comes out.
  2. Heat is always on and you can’t turn it down.
  3. Heater operates erratically, putting out more or less heat without any control changes.
  4. Coolant leaks.
  5. Low coolant level.
  6. Higher-than-normal temperature gauge readings (from loss of coolant)

What to check if heat is not working?

Check the Batteries in Your Thermostat If your thermostat runs on batteries, try replacing them. You’d be surprised how many times this simple fix gets a heater going again. It may sound like a no-brainer, but you do need to turn your thermostat to the “heat” or “automatic” setting before your heater will click on.

Why is my heater not heating?

Often, the issue is that the heating system is simply dirty. If your furnace has a dirty blower, the blower could cause equipment failure. In short, a dirty blower can cause the heat exchanger to fail. Dirty air filters could also be the reason your heater stopped working.

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