Why Is Cold Air Blowing When The Heat Is On
Your furnace may be blowing cold air because the filter is too dirty. A dirty air filter blocks airflow over the furnaces heat exchanger, causing it to overheat. When overheating, your furnace can trip a high limit switch, causing the furnace burners to shut off so that the heat exchanger does not crack.
On Winter Mornings Many Drivers Are Disappointed To Find Their Cars And 4x4s Have Heaters That Are Blowing Out Cold Air However It Isnt Always The Heater Thats To Blame The Heaters Warmth Is Derived From The Coolant Circulating Around The Engine To Cool It Down
In low temperatures, the coolant can freeze unless anti-freeze has been added. In the UK, where temperatures can unexpectedly plummet, most car owners should prepare ahead by ensuring the water tank is topped up and anti-freeze included. Even then, the engine needs to run a few minutes to heat the coolant sufficiently to release enough warmth as it passes the heater. Drivers of vans often speed up the process by placing a piece of cardboard between the radiator and the front bumper to reduce the amount of cold air flowing in. The radiator should never be totally covered and a smaller piece of card used if the coolant becomes too hot.
How Do I Reset My Heater
How to Reset an Electric Furnace First, turn off the power supply to the furnace by turning off the breaker in the circuit box. Locate the reset button on the furnace and press it to reset the furnace. If the button is popped up, press it down. Return the cover to the blower compartment and turn the power on.
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An Air Pocket In The Cooling System
Also known as an airlock, this type of large air pocket forms because coolant is leaking and air is introduced to the system. It can also occur when the coolant has been changed, or if a cooling system part has been replaced and the system was not purged adequately. A more serious reason may be an engine cylinder head gasket problem or a cracked part in the engine coolant chambers that pushes compressed air into the cooling system. Any air pocket will prevent proper coolant circulation uneven heat from your heater and can potentially cause engine and transmission overheating.
How Does A Car Heater Work
Before you get around your heater with your toolbox, you must know how does a heater work in a car and what are the car heating system components. A car is a machine, and every part works in combination with several other parts. Therefore, your car heater does not work in isolation.
So, first of all, lets check out what are the essential components of an automotive heating system. A car heating system includes:
- Heater core
- HVAC control panel
- Heater control valve
Then there are cooling system components in your car, such as the radiator, thermostat, coolant, and water pump. These systems work in unison to make your car work in the best possible manner without overheating it or cooling it excessively.
Now, come to the question of how a car heater works?. Your engine heats up as you drive, and it needs to be passed out. The exhaust system comes into play here and takes care of most of the heat. At the same time, the rest of the heat remains in the engine cast and is transferred to the coolant.
As it reaches a higher level, the thermostat opens, and the coolant flows in and passes the heat around the engine to the radiator and to the heater core, which exchanges the heat and sends the heat into the car cabin.
This heater can be controlled and adjusted to the desired level. The heater core is situated under the dashboard or on the passenger side wall under HVAC. The blower motor is the component that blows the air through the heater core and warms the car and passenger side.
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Bleeding Out The Cooling System
If youre maintaining your car properly, you should check the cooling system every time you do a service or at least once a year. Despite what most car manufacturers say, long-life coolant doesnt last nearly as long as it should. In most cases, it is good practice to change your coolant every 2-3 years. While changing coolant, theres a small chance of having pockets of air left behind inside the system if the system hasnt been bled properly.
Some cars feature a self bleeding cooling system, which makes everything a lot easier. Other cars have bleed valves located at several key points in the car. Bleed valves allow you to release air bubbles from the cooling system just by unscrewing them and waiting until coolant starts coming out. This should only be done when the engine is cold.
With the bleeding valve, or screw lightly unscrewed, turn on the car and let it idle until it reaches operating temperature. Check again if any coolant is missing and add the appropriate amount if needed. Check the coolant level frequently for the next couple of days. If youve done the job right, your car will maintain a stable temperature, and youll notice that the car heater blowing cold air issue is likely resolved.
What Are Some Signs Of A Defensive Driver
Defensive drivers follow these main practices:
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Faulty Blend Door Actuator
The blend door actuator, also known as the temperature blend door actuator or vent mode door actuator, can break or malfunction over time. A blend door actuator is faulty if the HVAC control module commands it to a certain position but it fails to comply, leading to situations like the temp blowing hotter or colder than its intended setting. A faulty blend door actuator can be identified with a powerful scan tool and sometimes makes a clicking noise from worn or broken internal parts.
Is The System Blocked By An Air Lock
Sometimes even with water in the system and a working thermostat, you can still get no heat the flow of water in the heating-and-cooling system may be blocked by air or dirt.
One possible cause is an air lock in the cooling system. If your system has a bleed port or bleed screw, and you can find it, you can fix this air lock yourself. Run the engine until the fan kicks in. Once your fan has come on, look around the radiator for a bleed port or bleed screw. This is something that can be turned with a screwdriver. Once you turn it anti-clockwise, you should hear a hiss this is the air being released.
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Theres An Issue With The Thermostat
If there are no leaks, blockages or loose hoses your problem could be your thermostat.
A badly installed thermostat will cause the engine to not produce any heat at all. This is because it regulates how much coolant goes into the radiator depending on temperature levels outside and inside of the car.
Your air conditioner system also requires a properly working thermostat in order to work correctly.
Replacing this part can be tricky but you need to know if this is whats causing your car heater to blow cold air before you go spend money on new parts for something that may just be a small switch made of plastic.
How Much Does It Cost To Fix A Car Heater
The costs involved in fixing a car heater can depend on the problem and what needs replaced or mended.
A full replacement of your heater core can be expensive due to the labour involved, costing upwards of £1,000 for parts and labour.
Find out whats causing your cars heating problems with Smart Care.
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Is There Enough Water In The Car
Your heater uses the heat from the coolant circulating around the engine. You should also have antifreeze in your coolant mixture, this not only stops the coolant from freezing inside your engine but also stops it from corroding. The heater is higher up than the rest of the cooling system, and thus last in line for coolant. Thus the first thing you should do, if you have no heat, is to see if there is, in fact, enough coolant in your engine.
You can do this by lifting the bonnet and looking at the header tank, which collects overflow coolant from the radiator. This is a large tank, usually clear plastic, with a conspicuous cap, rubber hoses coming off of it, and “Max” and “Min” markings on it. It is positioned a little higher than the radiator, usually to one side or the other of the engine, directly above a wheel.
If this tank is empty, you can fill it back up with ordinary water you can add some antifreeze if you want. If your header tank is full then proceed to the next step. If you are not certain which is your header tank, ask a friend, or take the car to a local garage.
How Do You Check If A Thermostat Is Working
Check the screen: Check the screen of the thermostat and make sure that it is lighted. A blank or unlighted screen could indicate a thermostat failure. Check the batteries: Many modern thermostats rely on battery power to operate. If the screen is blank or unlighted, a battery change could solve the problem.
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The Outside Temperature Is Too Low
You should check the actual outside temperature to see what its like. This can explain why the car is running for a while with no heat being produced, so keep this in mind.
On very cold days you need to let your car run for at least 10 minutes before using the heater just so that everything can get warmed up enough to start producing heat inside of it.
If not, then all you are doing by turning on your heater is draining your battery which doesnt help anyone!
On colder mornings there may be less heat produced because extreme cold outside makes it hard for your cars engine to generate any warmth while running during these conditions.
Is Your Car Heater Blowing Cold Air Fix It With Quality Parts
Now that you know what are the causes behind a car heater blowing cold air, its much easier to troubleshoot the issue and make sure which part needs to be replaced. If you notice your heater core is leaking or faulty, make sure to check out our website. Here at eEuroparts.com, we carry a wide array of OEM parts for your cars heating system.
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The Coolant Level Is Low
Your cars engine has a coolant fluid, water mixture, and antifreeze fluid.
This coolant prevents the engine from overheating and supports the heating system. If the coolant runs low, you will receive cold air in your car.
So, you should check the coolant level whenever the car heater blows cold air into the car. But it is advisable to let the car engine cool first before doing so.
Topping it up will solve the problem if you deduce the low coolant level.
But this might be a short-lived solution since the low coolant level indicates another issue. Therefore, you should also check what made it do so.
It could be an issue with the gasket or the hose. Hence, you might also want to check these two components to ensure they are fine.
If one of them is faulty, you must repair or replace it to prevent the coolant from running low again.
Failing Or Bad Blower Motor Resistor
It is the car heating system component that controls the fan speed. The knob that you use to change the speed is connected to the blower motor resistor, which changes the speed. If you frequently change the settings, it may cause the blower motor resistor to go off.
So, if your car heater not working properly and you are filled with amazement to figure out why is my car heater blowing cold air instead of hot air you must check a few things first such as:
- If the vents are not blowing hot air at certain settings, or
- If the fan is working on one speed only, or
- No air is coming off the vents at all.
If you find any of these signs, it confirms that your blower motor resistor is the reason why heater in car not blowing hot air.
Once again, it is an internal component, and fixing it on your own is a bit complex. So, it would be best if you had a mechanic. If it needs replacement, it cost around $100 to $160 for parts alone.
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Jammed Or Broken Blend Door
A blend door actuator plays many roles. The small plastic gear set serve to move air direction based on circulation modes mid vent, defrost, or floor. The blend door also serves as climate control, working to move temperature doors between cool and heat.
If the blend door is broken or stuck on cool, the heater core will be bypassed entirely and the heater will only blow cool air.
Blower Fan Not Working
Finally, one more reason the heater doesnt blow hot air is simply that the blower fan is not working correctly or at all, which may be caused by a blown fuse, a faulty motor, faulty control resistor or controller, or by faulty wiring.
How to Fix it: Blown fuses can indicate a problem that may need a professional diagnosis and repair. Additionally, check your cabin air filter. A filter that is clogged with debris, dust, and dirt will not allow the air to flow strongly through the heater core. This filter should be changed often, especially in dusty, dirty environments.
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Coolant Leaking Out Of The Exhaust While The Heater Is On
A coolant leak can indicate a blown head gasket.
When the gasket blows, the connection between the engine block and cylinder head is no longer air-tight, allowing coolant to escape through the tailpipe.
Structural flaws in the head or malfunctions in the intake manifold can also cause coolant to leak.
Broken Car Heater: Will It Fail Mot
If your car heater is not working, you may well be wondering if this will cause your vehicle to fail the MOT.
Whilst a broken car heater can be inconvenient , it is not one of the core components checked as part of an MOT.
Click here for a full list of car parts checked at an MOT.
Equally as frustrating as a car heater not working, is facing problems with your car air conditioning not working properly.
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How Does Cabin Heater System Work
There are numerous reasons why every car should have a fully working cabin heater system. Its not just meant to keep you warm during cold winter days when youre commuting to work, even though thats its primary purpose.
Assuming you have a car with an internal combustion engine , your car generates heat. Most of this heat is exchanged through the cooling system, which is why you need to have it properly maintained, but a good chunk of it is also used for heating up the cabin.
A car heater blowing cold air as soon as you start the engine is perfectly normal because the coolant hasnt reached optimal temperature yet. As the engine gets warmer, the thermostat opens up and lets the coolant circulate through the radiator, and later through the heater core, which finally heats up the passenger cabin.
The dials or buttons on your dashboard let you control the temperature inside the passenger cabin by opening and closing the intake of coolant to the heater core and by controlling the fans.
An Issue With The Cables
The cables can also make the car heater blow cold air. It happens when they are worn and unable to supply voltage to the heater.
The cable terminals may also be loose hence not making proper contact. So, you should also check their state when you encounter a heater issue.
If the cables are corroded, you have to replace them with new ones. Also, tightening their terminals might solve the problem if they are loose.
However, it is essential to take extra caution when handling them since they can cause shocks.
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