Why Does My Car Heat Only Work When I’m Driving?

When you’re driving, the car engine is working hard to get the car moving, and that means it’s generating a lot of heat.

The more heat your engine generates, the more heat you need from your heater.

That’s not to say it doesn’t work when you’re not driving, though it will still blow out hot air when you have the car turned off.

But if it were to work all the time, then you’d be burning up a lot of gas just to keep your car warm in between drives.

You could always turn on your engine and drive around for 20 minutes just so your car is nice and warm before getting out of it!

What’s the problem?

The heat in your car is controlled by an electronic thermostat. When you’re driving, the car’s computer receives information about your speed and acceleration from the engine control unit ECU.

The ECU then sends a signal to the engine coolant temperature sensor to tell it how fast the engine is running.

If your car’s computer has been damaged by water or corrosion, the ECU may not be able to communicate with the coolant temperature sensor properly and will not be able to tell when you’re driving, even if you are.

How do I fix this issue?

You need to determine if the ECU is damaged. You can do this by running an engine diagnostic test using a car code reader.

If the problem cannot be fixed by resetting the ECU, then you’ll need to replace it with a new one that has been reprogrammed for your vehicle’s model and year.

You can try to clean the ECU and the coolant temperature sensor with electrical contact cleaner.

If that doesn’t work, you may need to replace the ECU or the coolant temperature sensor.

What are the causes of heat in my car?

If you’ve checked your coolant levels and they’re fine, you can check your radiator fan by disconnecting it from its wiring harness so it doesn’t run while you’re testing things out.

If you see smoke coming from the fan or if it’s not running at all, then replace it immediately.

The thermostat is stuck open and allows too much coolant to flow out of the radiator without being heated up enough by the engine.

This can cause an overheating situation, so be sure to check that out first!

Your radiator is clogged with dirt or debris which prevents water from circulating properly through it.

You may need to take it off and clean it out thoroughly if this is the case.

If you have a manual transmission vehicle, it’s possible that your clutch plate has failed.

This means that there isn’t enough friction between these two parts when they come into contact with each other during acceleration or deceleration so they don’t work together properly anymore.

What are some solutions to this problem?

A blown fuse

Sometimes your car’s fuse box will need to be replaced if you’re having this problem.

A faulty thermostat

This can cause your car to only heat up when you’re driving, as well as other issues like overheating, coolant leaks, or a lack of power when accelerating.

A faulty water pump

If this is the cause, then you’ll also notice that your car doesn’t cool down properly when parked it might start feeling hot even after being turned off for several hours.


The reason your car’s heat only works when you’re driving is that it’s a safety measure.

If you were to get into an accident and have to evacuate the vehicle, you wouldn’t want to be stuck in the middle of winter without heat.

This is why the heating system only kicks in when the car is moving so that if you have to exit the vehicle for any reason, you’ll be able to do so quickly and safely.

Steven Hatman
Steven Hatman

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