How To Fix a Car With No Heat


If your car has no heat when you turn on the heater, that can be a problem during the wintertime. You should be able to know how to fix a car with no heat. I had this problem with my vehicle and I wanted to save some money by fixing it myself. I did some research which gave me a pretty clear idea of how to fix a car with no heat.

How To Fix a Car With No Heat

Fixing a car with no heat consists of performing a series of tests and replacing faulty parts. Here is how to fix a car with no heat:

1. Make sure your engine is cold

How To Fix a Car With No Heat

Before you start fixing a car with no heat, make sure that your engine is cold. One of the tests that you will perform is to check the level of antifreeze in your radiator. You can’t check the antifreeze if the engine is hot. So, check your dashboard temperature gauge and make sure it’s low.

2. Check the radiator for coolant

How To Fix a Car With No Heat

If you are low on coolant, your engine might not be able to work at the correct operating temperature. There will be not enough hot fluid to travel through the engine and into the mini radiator where the fan blows and hot air enters your cabin. So, open the radiator cap and check the level of your coolant. If you are missing coolant or you see a lot of gum buildup, see how to flush your cooling system. Adding more coolant to your radiator will fix your heating problem. After you performed the coolant flush, or you simply needed to add more coolant, make sure to close the radiator cap correctly because it is a pressurized system.

Your car is able to get hot air inside the cabin because the radiator fluid gets really hot and then runs through the engine and into your cabin via hoses. Just before the hot radiator fluid enters your cabin, there is a mini radiator that keeps the hot fluid there. Then, a fan blows over your heater core and that’s how you get hot air in the cabin of your vehicle.

3. Check the coolant reservoir

How To Fix a Car With No Heat

If your vehicle has a coolant reservoir, you should check the level of the coolant there. Usually, the coolant reservoir is located on the left side of the engine bay. It is a white plastic tank with markings for ”low level” and ”high level” on the side. Open the reservoir cap and see if you have any coolant inside. If you are low on coolant, make sure to add more. While adding, pay attention to the markings on the side of the plastic reservoir and make sure not to cross the top line.

Adding more coolant to the coolant reservoir will fix your heating problem. You should always check your manufacturer’s owner manual to make sure that you are adding the correct type of coolant.

4. Go for a test ride

If your vehicle was low on coolant and you added some or you performed a coolant flush, not its time to perform a test drive and see if this fixed your heating problem. Go for a test drive and make sure your engine has reached the proper operating temperature by looking at the temperature gauge. Turn on your heater and see if any hot air will come out. If there is hot air, then you have fixed the heater on your car. However, you should inspect the reason why your vehicle is losing coolant. Is It Safe To Drive With a Coolant Leak.

5. If your vehicle overheats on the test drive

While on the test drive, make sure to pay close attention to the temperature gauge on the dashboard. Once your engine reaches the proper temperature, the temperature gauge should stay in one place ( in the middle between ”C” and ”H”). But, if the temperature gauge continues to rise towards the ”H”, your vehicle is about to get overheated. How To Cool Down Overheating Engine Fast. Make sure that you do not let your vehicle to overheat.

When your vehicle overheats and you are not getting heat inside your vehicle, that’s because the water pump isn’t working properly. The impeller inside the water pump usually stops spinning the hot coolant and it won’t be forced into the heater core, thus making your engine overheat and you won’t get any heat in the cabin. What Are The Signs Of a Bad Water Pump?

6. Check your thermostat

6. Check your thermostat

If your vehicle is unable to reach the proper operating temperature and it never gets hot, this could be due to the absence of a thermostat, or your thermostat is stuck open. The cooling system is a closed pressurized system. Once the coolant reaches the needed temperature, it is up to the thermostat to open and let the coolant circulate through the cooling system.

If your thermostat is stuck in an open position, the coolant will circulate all the time and it won’t be able to get hot. So, follow the top radiator hose into the engine and where it meets the engine, there is your thermostat. There are usually two bolts, one on each side. Remove the bolts and install a new thermostat. A new thermostat in your vehicle will allow your engine to reach the proper operating temperature and you will have heat in your cabin.

7. Check your fan

Check your fan

Adjust the temperature on your heater and then adjust the fan level. If your fan isn’t working when you turn it on, that could be the reason why you are not getting heat inside the cabin. If your fan only works when it’s on high and you are not getting heat inside the cabin, then your blower motor resistor is probably bad.

8. Check the heater core hoses

Check the heater core hoses

The cause for your heater not blowing hot air could be a clogged heater core hoses and you will have to flush the system. If your heater only blows cold air even if you set up the temperature on hot, you should check your heater core and see if it’s clogged. Here is how to check your heater core and see if it’s clogged:

  1. Leave your engine running and set the temperature to hot.
  2. Go out to the engine bay and locate the hoses that go from the heater core into the firewall. They are usually located on the backside of the engine, on the passenger side, and run from the heater core into the firewall.
  3. Touch the heater core hoses and see if they are hot. Be careful not to burn your hand. Both of the hoses should be hot. If you have a thermometer, the temperature on the hoses should be around 140 degrees Fahrenheit.
  4. Just in case the heater core hoses are both cold, you will want to disconnect them from the firewall and perform a flush. There could be a gum buildup inside which prevents the hot coolant to run through them and into the firewall.

9. Check the heater control valve

If one or both heater core hoses that should be hot in order to transfer the heat into your cabin are cold to the touch, the reason for that could be a faulty heater control valve. The heater control valve could be operated by vacuum, cable, or electronic. In all cases, the heater control valve should open and close in synchronization when you switch the heating controls inside your cabin.

heater control valve

If the heater control valve is faulty, it will not open and let the hot coolant to run through the heater core hoses and you will not have heat in your cabin. In this case, you will have to replace your faulty heater control valve.

The heater control valve is located on top of the two heater core hoses on the backside of the engine. You can check if this valve is operational by adjusting the heater from the panel inside your cabin and see if the heater control valve moves (opens and closes).

10. Check the blend door actuator

Check the blend door actuator

If your car has no heat it could be due to a bad blend door actuator. A blend door actuator is located behind your heater panel controls and has a function to block the heater core or block the cold air depending on if you set the heater on cold or hot. When you set up the heat to hot(H), the blend door will block the cold air and allow only hot air to come in. When you set the heater control to cold(C), the blend door will block the heater core and only cold air will be able to come inside the cabin.

If your blend door actuator is faulty, the blend door could be stuck in a closed position and your cabin will not get hot air no matter how you set up the heater control panel. You can hear if the blend door is working because when you change the heat from hot to cold, the blend door makes a clicking noise as it turns. If you hear no noise, then your blend door is faulty and is stuck in one position. You can change the blend door actuator and you will have heat in your cabin.

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