Why is my car heater not blowing heat?
If your car's heater is not blowing hot air, there could be several underlying issues. The most common causes include a problem with the coolant system, a faulty thermostat, or a malfunctioning blower motor. Understanding the potential reasons behind this problem can help you diagnose and resolve the issue efficiently.
Potential Causes of a Non-Functioning Car Heater
Here are some of the most common reasons why your car's heater may not be blowing hot air:
- Low Coolant Level: The car's heating system relies on the circulation of hot coolant from the engine. If the coolant level is low, the heater core may not receive enough hot fluid to generate heat.
- Faulty Thermostat: The thermostat is responsible for regulating the flow of coolant to the heater core. If the thermostat is stuck in the closed position, it can prevent the coolant from circulating and reaching the desired temperature.
- Malfunctioning Blower Motor: The blower motor is the component that pushes the heated air from the heater core into the cabin. If the blower motor is not working, the hot air will not be able to reach the interior of the vehicle.
- Blocked Heater Core: Over time, the heater core can become clogged with debris or mineral buildup, restricting the flow of hot coolant and preventing the heater from functioning properly.
- Leaks in the Cooling System: If there are any leaks in the cooling system, it can cause the coolant level to drop, leading to a lack of heat from the heater.
Identifying the root cause of the issue is crucial for resolving the problem and restoring the functionality of your car's heater.
Troubleshooting Steps
To diagnose the problem, you can start by checking the coolant level and ensuring that the thermostat is functioning correctly. If the coolant level is low, top it up and check for any leaks in the system. If the thermostat is stuck, it may need to be replaced. Additionally, you can inspect the blower motor to ensure it is receiving power and operating as intended. If the heater core is blocked, it may require professional cleaning or replacement.
By following these troubleshooting steps and addressing the underlying issue, you can restore the proper functioning of your car's heater and enjoy a comfortable driving experience, even in colder weather.
How to unclog a heater core in a car?
To unclog a car's heater core, first disconnect the two heater hoses and drain the coolant. Then, use a garden hose or compressed air to flush the core in the reverse direction of the normal coolant flow until the water runs clear. If flushing alone doesn't work, try soaking the core with a dedicated radiator flush product or a diluted vinegar solution for 10-45 minutes before flushing again, always ensuring you dispose of the old coolant properly.
This video demonstrates how to flush a heater core using a garden hose and a radiator flush product: 51sChrisFixYouTube · Dec 2, 2014
Step 1: Prepare the vehicle and disconnect hoses
- Allow the engine to cool completely.
- Place a bucket under the heater hoses to catch the old coolant, which should be disposed of properly.
- Disconnect both heater hoses from the firewall.
You can watch this video to see how to disconnect the heater hoses: 1moxmanagainYouTube · Oct 21, 2020
Step 2: Flush the heater core
- Connect a garden hose to one of the heater core inlet/outlet ports and run water through the system.
- Point the other heater hose into the bucket or a drain container.
- Start with low water pressure, as a heater core is not built for high pressure.
- Flush until the water runs clear, which may take a few minutes.
- If the clog is stubborn, use a radiator flush product or a diluted white vinegar solution instead of water.
- Follow the product's instructions, letting it soak for the recommended time before flushing with water.
- You can also try flushing with compressed air, but throttle the pressure to prevent damage.
This video shows how to use compressed air to flush the heater core: 59sEricTheCarGuyYouTube · Jan 10, 2010
Step 3: Reassemble and refill the system
- Once the water is clear and all cleaning solutions have been flushed out, reconnect the hoses to the heater core ports.
- Refill the cooling system with a 50/50 mix of coolant and distilled water, as specified by your owner's manual.
- Turn on the engine and let it run until it reaches its normal operating temperature to bleed any trapped air from the system.
How much does it cost to fix a car heater blower?
The total cost to replace a car blower motor typically ranges from $200 to over $500, depending on the car's make and model, and whether the blower motor resistor also needs replacing. The parts can cost anywhere from $50 to $400, and labor costs can range from $75 to $150 or more per hour, depending on the complexity of the job.
This video explains the cost of replacing a blower motor: 56sCasey Services HVAC IncYouTube · Sep 15, 2025
Cost breakdown
- Parts: The cost for a new blower motor can be between $50 and $400 or more, varying by vehicle and part brand (Original Equipment Manufacturer vs. aftermarket). A blower motor resistor is a separate part that is often replaced at the same time and can cost from $20 to $70 or more.
- Labor: The time to replace a blower motor can range from about one to three hours, with labor rates typically between $75 and $150 per hour, depending on the shop and your location.
- Total Estimate:
- Low-end: Around $200, if the motor is inexpensive and the job is simple.
- Average: Roughly $400-$500.
- High-end: Up to $600 or more, especially if the motor and resistor need to be replaced and the labor is more extensive.
Factors that influence the cost
- Vehicle make and model: The year, make, and model of your car are the most significant factors, as labor and parts vary greatly between vehicles.
- Part choice: OEM (Original Equipment Manufacturer) parts are often more expensive than aftermarket parts.
- Labor rates: Labor costs differ based on geographic location and the specific repair shop.
- Complexity of the repair: The difficulty of accessing the blower motor can affect the total cost. On some vehicles, it may be a relatively quick and easy job, while on others, it requires removing parts of the dashboard, increasing labor time.
- Additional parts: If other components, such as the blower motor resistor, are damaged and need replacement, the total cost will be higher.
Why is my car blowing out cold air when the heat is on?
Your car is likely blowing cold air when the heat is on because of a low coolant level, a faulty thermostat, a clogged or broken heater core, or an airlock in the cooling system. Other possible causes include a bad blower motor, a clogged cabin air filter, or malfunctioning heating controls. To diagnose the problem, first check the coolant level and listen for the engine to reach its normal operating temperature.
You can watch this video to learn about the symptoms of a clogged or leaky heater core: 49sTop 5 Auto RepairsYouTube · Sep 14, 2023
Common causes
- Low coolant level: Coolant transfers heat from the engine to the heater core. If the level is too low, there isn't enough heat to warm the air. This is often caused by a leak in a hose, the radiator, or the water pump.
- Faulty thermostat: The thermostat regulates the flow of coolant. If it's stuck closed, coolant can't circulate to the heater core to provide heat.
- Clogged or damaged heater core: The heater core is a small radiator that heats the air. Over time, it can become clogged with debris or rust, preventing hot coolant from flowing through it properly.
- Airlock in the cooling system: Air bubbles can get trapped in the cooling system, blocking the flow of coolant to the heater core. This can be fixed by bleeding the air from the system.
- Malfunctioning heating controls: The cables or electronic components that control the blend door (which directs air over the heater core) or the temperature can break or become stuck.
What to check and do
- Check engine temperature: When the engine has been running for a while, check if the temperature gauge is in the normal range. If it's still on "cold," the thermostat is a likely culprit.
- Check coolant level: Look at the coolant reservoir. If the level is low, top it off with the correct mixture of coolant and water. Check for any signs of a leak, such as puddles under the car.
- Check for blockages: If coolant levels are normal, a blockage is likely. You can try a cooling system flush, or a mechanic can check for blockages in the heater core itself.
- Inspect heating controls: Check the vents and controls for any signs of damage or sticking. You may need to have them repaired or replaced.
This video explains the steps to troubleshoot a car heater blowing cold air: 1:06Dannys DIY GarageYouTube · Oct 22, 2025
Why is my heater blowing air but not hot?
If your heater is blowing air but no heat, it's likely due to a problem with the ignition system, thermostat, or airflow. You can start by checking simple issues like the thermostat settings and cleaning or replacing the air filter. If these don't work, a dirty flame sensor, pilot light, or a tripped high-limit switch could be the cause, and a professional should be consulted for more complex issues like a faulty gas valve, clogged burners, or a cracked heat exchanger.
Simple checks and fixes
- Check thermostat settings: Make sure the thermostat is set to "heat" and the temperature is higher than the current room temperature. If it's a digital thermostat, check the batteries.
- Check and replace the air filter: A clogged filter restricts airflow. Check it and replace it if it's dirty. A dirty filter can also trigger the high-limit switch, which shuts off the heat to prevent overheating.
- Cycle the power: Turn the furnace off, wait a few minutes, and then turn it back on. This can sometimes reset a tripped safety switch.
- Check the gas supply: If you have a gas furnace, ensure the gas valve is open. The handle should be parallel to the pipe for the "on" position.
- Relight the pilot light: If your furnace has a pilot light, it may have gone out. Follow the manufacturer's instructions to relight it. If the pilot won't stay lit, it could indicate a problem with the thermocouple.
When to call a professional
- Safety switches: If a simple reset or filter change doesn't work, the issue could be a safety switch like the high-limit switch or flame sensor.
- Gas valve or burner issues: Problems with the gas valve or burner igniters require professional servicing. They can also be a fire or carbon monoxide hazard.
- Cracked heat exchanger: A cracked heat exchanger is a dangerous issue that requires immediate professional attention and a complete system replacement.
- Ductwork issues: If the air isn't circulating properly, there could be a blockage in the ductwork. A professional can inspect and repair the ducts.
1:00Why your furnace is running but not heating (Pressure Switch Issues)YouTubeTaddy Digest · 1y 0:17Heater isn't blowing hot air anymore : r/hvacadviceRedditNate4343 · 10mo 0:05Unit running but not putting out hot air : r/hvacadviceRedditdiegowaffle · 1y 0:20Furnace not blowing warm air : r/hvacadviceRedditravenecw2 · 10mo 0:23Furnace not blowing hot air : r/hvacadviceRedditfoffucunt · 1y (function(){
(this||self).Bqpk9e=function(f,d,n,e,k,p){var g=document.getElementById(f);if(g&&(g.offsetWidth!==0||g.offsetHeight!==0)){var l=g.querySelector("div"),h=l.querySelector("div"),a=0;f=Math.max(l.scrollWidth-l.offsetWidth,0);if(d>0&&(h=h.children,a=h[d].offsetLeft-h[0].offsetLeft,e)){for(var m=a=0;m
