Why is my car not blowing heat from the vents?

There are several common reasons a car won’t produce heat at the vents, from simple settings to mechanical failures. The most frequent culprits involve coolant flow, the heating assembly, or the blower that pushes air through the vents.

What are the usual causes?

These are the typical faults that keep hot air from reaching the cabin. Start here to narrow down the problem.

• Low engine coolant level or a coolant leak


• Thermostat stuck open or failing to regulate engine temperature


• Air in the cooling system or a clogged heater core


• Faulty blower motor, resistor, or wiring preventing air from moving


• Faulty blend door actuator or HVAC control module that keeps the system on cold


• Blown fuses or relays affecting the blower or climate-control circuitry


• Cabin air filter blocked or dirty, reducing airflow into the cabin

These issues cover the bulk of cases where you don’t feel heat, from the path heat takes from the engine to the vents to how air is circulated inside the car. If you identify one of these problems, addressing it often restores heat without a full diagnostic.

How to diagnose heat problems at home

Following practical steps can help you pinpoint the cause without expensive diagnostics. Start with the simplest checks and move to more involved ones if needed.

• Verify that the climate controls are set to heat (not defrost or cold) and that the fan is turned up to a level that should push air through the vents


• Inspect or replace the cabin air filter if it’s dirty or clogged


• Check the blower fuse/relay and ensure the blower motor runs when you increase fan speed


• Feel the heater hoses under the hood after the engine has warmed up: one should be hot (heater core is receiving hot coolant); if both are cool, coolant flow or engine warm-up is the issue


• Check the coolant level in the reservoir and radiator (if accessible). Look for leaks under the car or around hoses


• If you suspect air in the cooling system, run the engine with the heater on full heat and follow the bleed procedure in your owner’s manual to remove air pockets


• Consider using an OBD-II scanner or a shop diagnostic to check for climate-control codes or module faults if the issue isn’t obvious

These steps help distinguish simple fixes (like a blown fuse or filter) from more involved problems (like a faulty heater core or blend door). If you’re uncomfortable performing any step, or the problem persists after the checks, professional help is advisable.

When to seek professional help

Some symptoms warrant a professional assessment, especially if you notice heat-related issues alongside other vehicle problems.

• Engine overheating or persistent coolant leaks


• Persistent lack of heat after basic checks and no clear DIY fix


• Blower runs but no air or inconsistent airflow even at high fan speeds


• Unusual smells (sweet coolant odor, burning smell) or visible smoke from the HVAC area


• Warning lights related to the engine, cooling system, or climate-control modules

In these cases, a mechanic can pressure-test the cooling system, diagnose blend-door or actuator faults, and verify HVAC control electronics to prevent further damage.

Summary

A lack of heat from the vents is most often caused by coolant or heating system issues (low coolant, thermostat problems, heater-core flow, or air in the system), airflow problems (blown fuses, failed blower motor, or a clogged cabin air filter), or HVAC control faults (blend-door actuator or control module). Start with simple checks—control settings, filter, and fuses—then verify cooling-system health and heater-core flow. When in doubt or if overheating or leaks are present, seek professional diagnostic and repair to avoid further damage.

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. 

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. 

Why is my car vent blowing cold air when the heat is on?

Your car's vents are blowing cold air when the heat is on due to issues like low coolant, a malfunctioning thermostat, a clogged heater core, or a problem with the blend door. The thermostat may be stuck open, preventing the engine from reaching the correct temperature, or air in the cooling system could be blocking hot coolant from reaching the heater core. Alternatively, a broken or stuck blend door could be preventing warm air from entering the cabin.
 
This video explains why your car's heater might be blowing cold air and how to troubleshoot the issue: 1mAuto V Fix YouTube · Jul 12, 2023
Potential causes

• Low coolant levels: If coolant is low, there may not be enough fluid to circulate to the heater core, which is responsible for heating the air. 
• Stuck thermostat: A thermostat that is stuck in the "open" position will prevent the engine from reaching its proper operating temperature, so the coolant never gets hot enough to heat the cabin. 
• Clogged heater core: The heater core can become blocked with debris or rust over time, preventing hot coolant from flowing through it and warming the air. 
• Air in the cooling system: Air pockets can get trapped in the cooling system and the heater core, preventing the hot coolant from heating the air. 
• Blend door malfunction: The blend door directs air to either the heater core or the AC evaporator. If the door is stuck in the "cold" position, it will allow only cold air to pass through, even when the heat is turned on. 
• Faulty heater controls: The cable or electronic switch that controls the blend door can malfunction or break, sending the wrong signal and keeping the door from moving to the heat position. 

How to diagnose the problem

• Check coolant level: Look at your coolant reservoir and make sure the level is correct. Also, inspect for any visible leaks under the car. 
• Inspect heater hoses: When the engine is warm, carefully feel the two heater hoses that run into the firewall. If one hose is hot and the other is cool, it indicates a blockage in the heater core. 
• Monitor engine temperature: Check if your engine's temperature gauge reaches the normal operating temperature. If it stays on "C" for an extended period, the thermostat may be faulty. 

You can watch this video to see how a blend door works and what happens when it's not working correctly: 57s1A Auto: Repair Tips & Secrets Only Mechanics KnowYouTube · Oct 19, 2022

Why is heat not coming out of my car vents?

If the blower motor fails, it can result in the car heater blowing cold air instead of warm air. If it's not working correctly, you might not feel any air coming out of the vents, even if the rest of the heating system is functioning. This could be due to electrical issues, a blown fuse, or the motor failing.