You are currently viewing Why My Car Heater Is Blowing Warm Air?

Why My Car Heater Is Blowing Warm Air?

Imagine you’re driving your car on a cold, wintery morning and crank the heat up. But after a few minutes, you’ll notice it still isn’t blowing hot air and blowing warm air. Which will keep you wondering why my car heater is blowing warm air and not hot air? In this article, we’ll discuss this car heater problem in detail.

How Does Your Car’s Heater work?

The heater core (much like the radiator) dissipates heat by dramatically increasing the surface area of the heated coolant. Once the hot coolant is in the heater core, a fan blows the hot air around the little metal bits which heat the air up. This hot air then ends up in your cabin.

Why My Car Heater Is Blowing Warm Air?

The answer is generally that some part of your heating system is partly plugged. In a lot of cases, this is because the thermostat itself is stuck in a partially open position. The thermostat regulates the flow of coolant into the heater core. If your thermostat is partially stuck, some hot coolant will flow into the heater core. This is the warm air you feel. But, because the thermostat is stuck your heater core is not getting enough coolant to provide enough heat for the air in your cabin to get hot.

Reasons Behind Your Car Heater Blowing Warm Air?

Let us now see what is causing the heater to blow warm air and not hot air. There are several reasons behind this issue such as heater control valve, faulty heater core, low coolant level, etc.

1. Heater Control Valve:-

The car heater valve is responsible for controlling the temperature of air blowing inside your car’s cabin. This valve controls the amount of coolant that flies inside the heater core according to the heater temperature requested by you. If this valve gets jammed or becomes faulty, the heater core will not be able to adjust according to your needs until you get this valve fixed or replaced.

2. Faulty Heater Core:-

The heater core’s maze-like network of tubes is susceptible to clogging and leaks, reducing the coolant level or flow through your engine’s cooling system. 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.

3. Malfunctioning Thermostat:-

A damaged thermostat may become stuck in the open or closed position. When stuck open, the thermostat may allow too much coolant to flow. By preventing your car from reaching its optimum operating temperature. Thereby causing a decrease in performance. On the other hand, a thermostat that’s stuck in the closed position won’t allow coolant to circulate, interrupting the system that cools your engine and heats your cabin.

4. Inoperative Blower Fan:-

Various issues may cause your blower fan to malfunction, including a blown fuse or damage to the blower fan’s internal components. Regardless, if you can barely hear or feel a breeze when your car heater is running, issues with the blower fan may be to blame!

5. Low Coolant Level:-

Coolant is used to maintain an optimum temperature inside your car’s engine block, especially, during extreme summers. Once the coolant extracts the heat from the engine, it is passed on from the heater core which blows hot air into your car if the heater is turned on. So, if your car is low on coolant, your car heater won’t work properly at all.

6. Cooling System Leak:-

Another reason behind the car heater issues is the possible leak. You should thoroughly check your car’s hoses, radiator, and water pump for any signs of leakage. If you spot any sign of leakage in the hose or spot water leaking from your car be responsible for my car heater is blowing warm air and not hot air.

7. Clogged Radiator:-

It is normal for heater radiators to clog over time and should come as no surprise to car owners, especially those with really old vehicles. But avoid disregarding early signs of obstruction. When a radiator plugs up, it becomes more difficult for the coolant to pass through its bearings leading to the car heater not getting hot when it needs to.

8. Failing Water Pump:-

Water pump issues share a common symptom with a clogged radiator, specifically extremely high engine temperature readings. This indicator may happen sporadically or alongside recurring engine overheating. During this occurrence, the pump can no longer circulate hot water or coolant throughout the engine block and heater core. Ultimately, the heater core will not heat up, rendering the car heater inoperable.

Therefore, these are some basic reasons behind this issue which will answer your question about why my car heater is blowing warm air and not hot air.

What To Do If Your Car Heater Blows Warm Air?

You can usually fix this with some penetrating oil as well as manually working the thermostat back open. The other issue that we commonly see is a blockage in the heater core itself. As we mentioned earlier, older heater cores can get plugged by rust or other gunk. This can prevent coolant from fully circulating through the heater core, which warms the air. To fix this issue, you’ll likely need a coolant change or flush, which you should be getting regularly anyway. Clean coolant helps keep blocks from happening.


We hope the above-mentioned information will answer your question about why my car heater is blowing warm air? and will be helpful to all the readers. If anybody’s doubts persist feel free to comment in the comment section below. We’ll try to solve your doubts as soon as possible.