Why does my car heater work intermittently?

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 the heat in my car going in and out?

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.”

Why does my heater not work sometimes?

Dirty and clogged filters are one of the primary causes of furnace problems and can cause high operating costs. The heat exchanger can overheat and shut off quickly when filters are clogged with dust and dirt. This also causes soot buildup on the heat exchanger, which makes your furnace run less efficiently.

Why does my heater get hot then cold?

Your furnace may be blowing cold air because the filter is too dirty. A dirty air filter blocks airflow over the furnace’s heat exchanger, causing it to overheat. When overheating, your furnace can trip a high limit switch, causing the furnace burners to shut off so that the heat exchanger does not crack.

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Why does the heat in my car get cold when I stop?

You may have trapped air in the cooling system or the heater core may be partially plugged up. Engine coolant is delivered to the heater core through two heater hoses.

What to check if heat is not working?

Thermostat not turning on heat



Make sure the switch is on “Heat” rather than on “Cool.” Check the temperature setting. Compare the temperature setting to the room temperature. Set the temperature five degrees higher than the room temperature and see if the furnace kicks on.

How do I know if my heater core is clogged?

There are several telltale signs that you’re experiencing a heater core problem:

  1. You have little or no heat inside your car. …
  2. You smell coolant inside your vehicle. …
  3. Your windows fog up. …
  4. You see signs of a coolant leak under the dashboard. …
  5. Your coolant level is dropping, or your engine is running hot.

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.

How do you troubleshoot an electric heater?

1. Your Electric Furnace Won’t Turn On

  1. Make Sure the Unit is On. …
  2. Check for Tripped Breakers. …
  3. Look for Blown Fuses. …
  4. Try Adjusting your Electric Furnace’s Thermostat. …
  5. Check your Furnace’s Filter. …
  6. Examine the Fan and Blower. …
  7. Make Sure the Thermostat is on the Right Setting. …
  8. Call in a Professional if that Doesn’t Work.
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Why is my heater not blowing out hot air?

Make sure that airflow into your furnace is not blocked or limited. If the furnace heats up just fine but continuously blows even when it is not putting out warm air there can be a problem with your limit switch. … If your furnace does not heat up enough you might have an ignition or pilot issue.

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