How to Fix if Car Heater is Not Working or It is Blowing Cold Air?

In this article, we will learn what is car heater, its parts, how to fix if car is not working or car heater is blowing cold air?

Let’s explore!

What is Car Heater? Basics

During the cold season, a broken heater of a car feels much more important than a broken Air conditioner during the summers. This veridically becomes an issue and a safety issue since the heat is required to remove fog and ice that has built up on your car’s windshield, and also, the extreme cold is not safe for the passengers inside the car. Whenever the weather gets a bit cold, nothing comes in more handy than the car’s heater.

Although the temperature outside of the car is wet, windy, or cold, the heating system of your car keeps you and your passengers warm. The engine’s heating system directly controls the cooling system of an engine. The controls of the car’s heater might be on the dashboard of the car, but the total mechanism and the work of the heater are inside the engine with its cooling system. Proper maintenance on that system not only benefits the engine but also helps to maintain your vehicle’s heater in excellent working order.

Parts of a Car’s Heater

The heating system consists of a few basic components like a heater core, blower motor/fan, heater hoses, heater control valve, and HVAC (heating, ventilation, and air conditioning) control panel/assembly. In addition, a coolant, thermostat, radiator, and water pump are some of the cooling system components that interact with the heating system. Vehicles also have a heater core for cooling purposes.

Heater Core or the control valve

A heater core is a device present inside a car that acts as a heat exchanger, which is used in heating the cabin of vehicles such as cars. The heater core is used in cars for more convenience and the same idea as the heaters used in contemporary homes.

Heater cores take the heat away from the hot coolant, and then the Coolant should be dispersed into the atmosphere. The heater core likewise removes heat from the heated coolant but pumps it into the vehicle interior through the air vents using a blower motor.

Also Read: Types of Cars

Blower Fan

Based on the climate system settings and the speed set by the driver, the blower motor is responsible for pushing heated or cooled air through the dashboard vents in accordance with the temperature settings. It is made up of a resistor that sends a signal to the blower motor when you adjust the fan speed, so that it either picks up or slows down, depending on the setting.

Thermostat

As far as thermostats are concerned, they are simply the devices that regulate the temperature of a heating system. The thermostat allows you to select a preferred temperature for your room or boiler, and it will work to maintain that temperature as long as you set the temperature. A thermostat is used to decide whether to turn on the heating system if the temperature in the home starts to drop.

The thermostat in your automobile is a crucial yet straightforward part. It’s a valve in the cooling system of your automobile. Its responsibility is to control how much coolant is pumped back into the engine and how much is cooled using the radiator before being pumped back into the engine.

Radiator of the heater

In order to break down the excess heat that is picked up by the liquid, the liquid is sent back to the radiator, with the radiator blowing air across it in order to cool it down, which then exchanges the heat with the air outside the vehicle. As part of the cooling process, thin metal fins are used during the radiator’s construction, which are effective in allowing heat to escape rapidly to the air outside the car, in the process of cooling.

The heater core, which essentially serves as a heat exchanger, receives heat from the engine through the radiator. It let coolant to pass through, while the heater control valve controls how much coolant flows through.

Also read: Types of bikes

Heater Hoses

It is the heater hoses which are used to circulate the engine coolant from the engine to the heater core, which is the small radiator which provides heat for the cabin of the car. The core is usually located inside the dashboard of a vehicle and extends from the engine to the firewall due to the fact that it is connected to the engine.

Heater hoses are used to transfer excess heat from the engine, which is represented by engine coolant, into the heater core in order to reduce the temperature of the engine. In order for the heated engine coolant to reach the heater core, it must travel through a number of small tubes within the heater core in order to reach it.

In a typical cooling system in an automobile, there are at least four main hoses that are connected to each other in a series of concentric loops. In order to connect the upper radiator hose to the thermostat housing, there is a hole it as well. At the bottom of the radiator, there is an attachment for the lower radiator hose.

During the cold season, a broken heater of a car feels much more important than a broken Air conditioner during the summers. This veridically becomes an issue and a safety issue since the heat is required to remove fog and ice that has built up on your car’s windshield, and also, the extreme cold is not safe for the passengers inside the car.

Also Read: What is Governer

How Does a Car’s Heater Work?

The cabin of a car starts to heat up when the car engine’s coolants heat up.

An engine creates so much heat from combustion and friction that if it isn’t constantly cooled, it may cause catastrophic damage. Without a doubt, all modern car engines are liquid-cooled, which means they utilize water combined with antifreeze to reduce corrosion and keep them from freezing.

An engine’s cooling system is filled with liquid coolant that flows between the engine and the primary automotive radiator. The flow of coolant in the device is created by the portion known as a water pump.

The workflow of the car heater is discussed below:

• The coolant is poured through tubes called water jackets in the engine, where it absorbs heat. It then passes through the radiator to cool before returning to the engine continuously.

• The heat produced by the engine running accumulates and requires a place to escape. A large portion of this heat is routed via the exhaust mechanism. The heat that has been stored up inside the engine casting is transferred to the coolant.

• Once the vehicle reaches operating temperature, the thermostat opens, allowing coolant from the cooling system to circulate through the engine passages, removing heat from the engine and sending it to the radiator, which then circulates to the heater core, which distributes this heat into the vehicle’s cabin.

• The heater core functions as a heat exchanger and is similar to a miniature radiator. It is often installed on the passenger side of the car beneath the dashboard or in the HVAC unit near the firewall.

• This component includes an inlet and an outlet to enable coolant to circulate through the core. The blower motor circulates air through the heater core and into the passenger compartment of your vehicle. The heater control valve regulates the flow of hot engine coolant via the heater core.

• In order for the heater to function efficaciously, the cooling gadget must be in super operating order. Having the appropriate combination of easy coolant and water to provide the right safety level, this is about 32 degrees Fahrenheit in our surroundings.

Also Read: What is Engine

Symptoms of a Faulty or Malfunctioning Car Heater Core

The following are indicators or symptoms of a faulty or failed heater core in an internal combustion engine:

Inoperable heater

A common sign of a failed heater core is when the heater stops working due to a blockage in the cooling system. If this happens, there probably aren’t any leaks in the system, but the heater core will have a hard time working.

Slimy film on the windows

When the heater stops operating owing to an obstruction in the cooling system, this is a frequent indicator of a failed heater core. If this occurs, there aren’t likely to be any leaks in the system, but the heater core will struggle to function.

Sweet Odour in the interior of the car

A sudden sweet odor in the automobile is another poor indicator of the heater core. In this case, fogging is accompanied by a lovely scent that suddenly permeates the cabin. Again, the scent might be somewhat pleasant, but it is very dangerous to inhale.

If your heater core is defective, you must fix it as quickly as possible since driving a vehicle with a faulty heater core is dangerous. It may cause overheating and severe engine damage.

Also Read: Fuel Pump

Car Heater is Not Working Properly: Key Reasons

During cold temperatures, the car heater makes any journey very comfortable.

Even though the vehicle heater’s operation is straightforward, it might fail for a variety of reasons. Therefore, rather than suffering through the harsh winter, you should get your vehicle heater examined well in advance rather than suffering through the harsh winter.

Below are some of the reasons that could be the cause of the damage to the car’s heater

Lower level of Coolant

Coolant is used to keep the engine block of your automobile at an optimal temperature, particularly during hot summers. After the coolant extracts heat from the engine, it is sent to the heater core, which blows hot air into the vehicle when the heater is turned on. As a result, if your automobile is low on coolant, your car heater will not function correctly.

When your coolant levels fall, the hot fluid cannot reach the heater core, and your cabin stays cold. This might happen if the engine works too hard and overheats or if it is not properly fuelled.

Problems with the heater fan

While hot coolant/antifreeze is being pushed into the heater core, the heater fan, which is responsible for blowing heat into the cabin, might break or suffer an electrical short.

Control Valve of the heater

The car heater valve is in charge of regulating the temperature of the air flowing within your vehicle’s interior. This valve regulates the amount of refrigerant flowing through the heater core in response to the selected heater temperature. If this valve becomes jammed or malfunctioning, the heater middle will no longer be able to adjust in accordance with your demands until this valve is repaired or replaced.

Defective Controls

The controls of the cooling and heating system of a car work perfectly fine when a car is brand new.  With use and time, the controls begin to malfunction and overuse can cause the controls to stick. The controls rarely get damaged, but you should still get them checked while doing your car service.

Draining Radiator

A draining radiator could block the coolant from reaching the car’s heater core and could also damage your engine.

Leak in the Cooling System

Another cause of vehicle heating problems is a probable leak. Check your vehicle’s hoses, radiator, and water pump for any symptoms of leaking. If you see any signs of hose leakage or water leaking from the surface, contact a mechanic and get the car inspected or try to have it repaired by yourself.

Blown Fuses or Faulty Wiring

Your car’s wiring might be damaged or have a short in it. This would imply that the heating is not activated when the driver instructs it to do so, which is not a good sign for your car engine as a whole.

Broken Thermostat

The thermostat is another reason why your vehicle heater may be producing chilly air.  If your car’s temperature gauge stays at C after your engine has had enough time to warm up, you have a faulty thermostat. The vehicle’s cooling system may not activate in this case. Since the heater core will not receive coolant, it will not be able to transmit hot air into the passenger compartment.

Also Read: Gear Box

Car Heater is Not Working Properly: How to Maintain?

If your heater isn’t heating properly, it might be due to a faulty blower motor or faulty actuators that aren’t functioning the blend doors properly.

Other reasons include a damaged engine thermostat, leaks or low coolant levels in the cooling system, or a faulty water pump, all of which will impair engine performance. In addition, many automobiles feature a cabin air filter, and if it becomes clogged, the heater’s performance suffers. The majority of the filters are located near the glove box of a car.

Your car’s cooling system should be properly maintained in order for the heating machine to characteristic properly. Therefore, it’s far essential to have your engine’s coolant cleansed and changed with an easy coolant/water mix on an everyday foundation, as well as to repair any leaks to your cooling system.

The heater temperature control in much older automobiles occasionally regulates the water flow via the tiny radiator, but this isn’t done in newer cars – it’s entirely down to airflow management.

Because there is no easy supply of waste heat, heaters are expected to become increasingly electrically powered as electric vehicles become popular. Also, since more automobiles have air conditioning these days, reverse-cycle systems, which are considerably more efficient than resistive heating components, are expected to become the standard, and because that power needs to come from the car’s battery, it’s best not to squander it needlessly.

It is recommended that you must inspect your cooling system on a regular basis and change each of the oils so that you will be aware of any cooling system issues and can get them repaired before they turn into a bigger issue.

Also Read: Cheapest Cars

How to Repair a Non-Working Car Heater?

Many things may go wrong in a car’s cooling system, which would lead the whole system to perform badly or not at all. The first item on the list is to ensure that the engine heats up correctly. When driving, it takes roughly 5-10 minutes for an engine to attain the right temperature.

The heating device is simple to use and fails only occasionally. The only defect that is likely to occur is when the fan ceases to run owing to a break in the electric circuit. This circuit consists of a feed cable from the fusebox to the on/off switch on the dashboard or centre console, as well as every other line from the switch to the heater motor. In addition, the engine is often earthed to the frame through a separate wire.

In most cars, the heater motor is located under the centre of the dash, making it unreachable. However, in a few instances, the engine is located beneath the hood near the back of the bulkhead.

The most basic cause of any problem with a car’s heater is a blown a fuse. This is usually in the main fusebox; however, it might be an in-line fuse connected to the motor’s supply. Check out a workshop manual for the precise location of the fuse. If it protects additional circuits that have also ceased functioning, the issue should be resolved by installing a new fuse.

A few things to do in order to fix a faulty heater are as follows :

Check the wiring

If replacing the fuse does not solve the issue, or if the other components controlled by the fuse are functioning normally, look for loose, unclean, stuck, or disconnected wires.

You can refer to the diagram of the heater wires and find out the locations of each wire and then follow the wires as far as you possibly can while thoroughly checking each connection.

Earth inspection

After checking the wiring, if you did not find any wires that are damaged, examine the heater motor’s earth connection. This is normally found on the bulkhead and may have deteriorated.

Clean any corrosion from the mating surfaces using dry or moist paper before refitting the fastening nut or screw and ensuring it is tight. To prevent additional corrosion, apply Vaseline to the connection.

Also Read: Power steering fluid

Examining a Heater Fan Circuit in Car Heater

Firstly, make sure your test lamp clip is earthed while carrying out your tests.

Start the engine and turn on the fan. Disconnect the motor feed wires (a multi-connector plug is used here) and probe the terminals. If the bulb illuminates, the current is present, and the motor will likely malfunction. If the lamp does not light up, check the switch.

Remove the switch from the dash and, while it is still turned on, probe the output terminals. If the bulb illuminates, the wiring between the switch and the motor is defective. If it does not, check the switch input terminal as well. If the bulb illuminates, the switch is faulty. If it does not light up, check the fusebox for power for checking the fan circuit of a heater.

With the light on, check the fuse output terminal. If the lamp does not light, replace the fuse and try again. If the lamp comes on, but the heater still doesn’t work, the wiring between the fuse box and the switch is broken.

Utilize a test lamp

If you can not find a problem with the wiring, use a test bulb to see if there is a power source for the motor.

Connect one end of the test lamp to a ground point. Disconnect the power cords from the motor. Single plugs or multiple plugs are possible. Start the engine and turn the engine switch to either one of the positions.

Using the test bulb, probe each wire in turn. If the lamp lights up, the current has reached that point. Next, repair the heating switch in the other position. If the bulb illuminates on both wires, the issue is with the motor.

If there is no power at the motor, the connections at the switch must be checked. Probe the output terminals first, alternating between low and high speeds. If the test bulb illuminates on the output terminals, the wiring between the switch and motor is faulty, and you should seek professional assistance.

Check the input terminal if the bulb does not illuminate. If the test bulb illuminates, the switch is defective. If the test bulb does not light up when you touch the input terminal, the wiring between the fuse box and the switch is defective, and you should visit an auto electrician.

Examine the Motor

A circuit tester is required to inspect the motor windings. This is comparable to a test light; however, it runs on its own battery.

Disconnect the battery and the cables connected to the motor and note how they fit. Next, connect one end of the tester to the engine ground lead and test each power connection individually.

If the tester lights up on all of the terminals, the motor is working properly. However, if the tester fails to light, the motor has blown and must be replaced.

Also Read: Top German Car Brands

Car Heater is Not Blowing Any Air: How to Fix?

If the heater isn’t blowing any air, it might be due to a defective blower motor or electrical connection. To repair it, follow these below-mentioned procedures.

Check to see whether the blower motor is receiving electricity

The only way to figure out which component failed is to get some simple diagnostic tools, access the blower motor, and see whether it gets electricity. The particular diagnostic technique differs depending on the vehicle.

Whether it gets electricity, check to see if the blower motor is damaged

After removing the blower, you may discover a squirrel cage so clogged with junk that the motor no longer works. In other circumstances, the problem might be a damaged wire, rusty connectors, or a detached pigtail assembly.

If the blower isn’t getting electricity, make sure the blower fuse isn’t blown

Because a blown a fuse often reveals an underlying issue, never replace it with a bigger fuse to avoid it from blowing out again.

If you replace a blown a fuse with one of the same amperages and it still doesn’t work, the fuse is most likely blown due to age. Unless the original fuse is not blown, try checking the resistor, relay, and switch to find the cause of the issue.

Also Read: Sports Car

Car Heater is Blowing Cold Air: Reasons & How to Fix?

In the middle of a bitterly cold winter, you have every reason to be frustrated if your car heater suddenly starts blowing out cold air instead of heat, and this is also happening at the worst possible time. There is no doubt that unreliable car heaters can make winter months virtually unbearable during the cold winter months.

Due to the fact that automotive heaters are very much like home heating systems in the sense that they have many components working together to heat your car, it is possible for a variety of things to go wrong. Your vehicle may blow out cool air instead of heating air if any or all of the following issues are present:

The reason and the methods of fixing the car heater if it starts to blow cold air are as follows:

Not sufficient amount of coolant

It is important to understand that the coolant in your engine, which is generally a mixture of water and antifreeze in equal proportions, not only functions to keep the engine from overheating but also to donate heat to the heating system. There is a possibility that the heater core will blow cold air into the cabin if there is not enough coolant in the system.

How to fix

In the event that you have confirmed that the problem is due to a low coolant level, you simply have to top off your coolant reservoir. If you have just recently refilled your coolant, you may want to check for leaks as well.

Faulty Thermostat

If your car’s thermostat stays on “C” even after the engine has been running for some time, then you may have a malfunctioning thermostat, since it may still be set to “C” even after the engine has been running for some time. It is important to note that when the thermostat is unable to send a signal that the engine is warm, it won’t send the coolant over to provide heat to the heater core, resulting in cold air blowing out.

How to fix

The thermostat in your heater needs to be replaced in order for it to work again. This is a relatively quick and easy fix that can be done in a few minutes.

Issues regarding the heater core

The heater core is a cooling system that looks like a compact radiator, but is actually a cooling system. The cooling system consists of a metal tubing system that transports the coolant in and out, as well as fans that are used to disperse the heat that has been released by the system. These are some of the signs that you may notice if your heater core is clogged or has other problems, including:

• A sweet type of odour
• Overheating of the car’s engine
• Presence of fog in the cabin of the car
• The car uses the coolant faster and very often.

How to Fix

There are a couple of ways to fix a clogged heater core passage. One way is to flush it out, and another way is to manually clean the exterior of the heater core by removing any debris that has accumulated on top of it. The heater core may need to be replaced in some cases, so it is important to check this beforehand.  

Stuck blended Door

A broken or jammed door can also be the reason why the car heater is blowing out cold air. The purpose of this feature is to allow the air to move from the heating system to the internal parts of the vehicle. The air bypasses the heater core if it is jammed, and you will end up with a cold air blowing out of your car heater.

How to fix

In order to fix the problem, you will need to replace the blender door. In most cases, a jammed blender is fixed along with other, more significant repairs

Leaking Water Problem

Last but not least, one of the most common problems with car heaters is a water leak. The hoses, radiator, and water pump are all places where leaks can occur, so you should make sure you check them for damage to see if they are damaged. You will not be able to use the heater of your car if any of these three are leaking

How to fix

You must check out for the place where the water leak has happened, once after locating the place of the water leak, then fix the leak with adhesive or any other method. If the water leak that is found is larger or in many places than one then the part must be totally replaced.

Replacements for Car Heaters

A damaged car heater might cost like a thousand dollars for a replacement, and sometimes the car’s heater cannot even be repaired.

The issue is that if you do not repair your car heater before winter arrives, you will be driving a vehicle that is ice cold on the inside.

The easiest solution would be to install a 12V vehicle heater and connect it directly to the electrical system. The issue is that electric heaters can’t compete with heaters that utilize hot engine coolant as a heat source.

The problem with most alternative vehicle heaters is that the heat contained in the engine coolant, which is the heat source used by factory heating systems, is basically free.

Because hot coolant is a consequence of regular engine function, and heat must be shed through a radiator anyway, drawing it out via a heater core requires no additional energy expenditure other than the little amount required to drive a blower motor.

The majority of vehicle heater options are electric, and electric heaters use a lot of electricity. If you’ve ever driven around with a portable electric car heater, you’re aware of how anemic most of them are. Most electric car heaters are more powerful than a hairdryer, so you must be careful while you make the replacement.

So an electric heater is not the answer to a damaged automobile heater—specifically, a defective heater core. For those expecting a cheap or simple remedy, this implies that the only genuine option, short of restoring the faulty heater properly, is a new vehicle heater that uses hot coolant like the original system.

How Effective Are Replacement Car Heaters?

Electric vehicle warmers are ineffective. There is a significant difference between weak battery-powered heaters, cigarette lighter heaters, and more powerful devices that need a direct connection to a vehicle battery. However, even the more powerful versions pale in contrast to the heat output of a factory heater.

Replacement vehicle warmers that operate on hot engine coolant rather than electricity are a different story. Some of these devices are still underpowered in comparison to a factory system, while others feature blower motors that aren’t quite as powerful as factory blowers. Top-of-the-line replacement vehicle heaters, on the other hand, may provide a significant quantity of heat.

Average Wattages for different kinds of replacement of car heaters compromise of :

• Cigarette lighter heater: 150 wattages
• Dual-mode electric heater: 150 to 280 wattages
• Direct-wired electric heater: 300 wattages

Also Read: Most Expensive Cars

Other Alternatives for a Car Heater

There are several cheaper alternatives you can use if your heater suddenly gets broken or you do not have the means to repair the heater at that moment. Some of these alternatives are listed below:

Windshield Cover

If you live in an area where the temperature is extremely low, and there is a heavy amount of snowfall. Using a windshield cover will not help you in scrapping off the snow in your pathway but also provides some amount of thermal insulation.

Purchase Heated Clothing

If you currently do not want to spend a few hundred bucks on repairing the car’s heater and also do not go through the process of repairing the car’s heater yourself

You may try it out with a handful of hot clothing items. Heated jackets seem to be the most costly, with the average cost being much less.

Invest in a car seat heater

A car seat heater is a pad or cushion that has an electric heating system that raises the surface temperature of an automobile seat for the comfort of the passengers.

While it will not heat the whole vehicle, this car seat warmer will keep you warm on your way to work or wherever your travel.

Buy a portable car heater

A portable car heater is generally a 12v heater which is very much more budget-friendly than a normal car heater. A portable car heater may be plugged straight into a 12v outlet (also known as cigarette lighters). Some types may also function as a defroster, which is one of the most significant issues in a vehicle without heat.

How much does it take to fix a car’s heater?

Depending on the amount of damage to the car’s heater, the repairs range from $300 to $1,000. The most common problem is a coolant level drop or a leakage within the coolant system.

A blower motor replacement costs between $363 and $394 on average. Labor expenses are projected to range between $87 and $111, with components costing between $276 and $283.

Frequently Asked Questions

High Rated Automotive Engineering Course

Automotive 101: A Beginners Guide To Automotive Repair

Automotive Engineering: Automobile Fundamentals and Advanced

Automotive Engineering; Hybrid Electric Vehicles

Do it Yourself – Automotive Electrical Diagnosis – Beginner

Do it Yourself-Automotive Electrical Diagnosis-Intermediate

Automotive Engineering; Common Rail Direct Injection(CRDI)

Fundamentals of Internal Combustion Engines – IC Engines

Hybrid and Electric Vehicle for Beginners FULL Course 2021

Automobile Safety: Understanding Car Crashes for beginners

Hybrid Vehicles The Fundamentals & Operating Principles

Introduction to Automotive engineering – Performance

Automotive 102: Battery, Charging System & Starting System

If you are interested to have certificate programs

Get started in your dream career today with 60% off registration at IAP Career College.

Our Videos

Refer YouTube

Our Apps

Check out our ‘MechStudies – The Learning App’ in iOS & Android

Check out our most viewed articles,

What is thermodynamics

Intensitve & Extensive Properties

What is Pressure

Bernoulli’s theorem

Venturi meter

Pump basics

Globe valve

Siphon

Reference Articles