Should car heater be working when engine is on but I am not driving?
I recently had my car engine, radiator and thermostat replaced as previous engine overheated due to a radiator leak. It seems to be working fine now however the heat isn’t coming on when the engine is on. However when I start driving for a minute and it comes on and works fine. Is this normal or should it be giving heat when stationary regardless of whether you are driving or not? just to add, I timed it today, its was about 2c, I started the car and after 10 minutes despite being on the highest heat setting i could only detect a small increase in heat and I think the slight heat came after i revved it a little. i got fed up and just moved off. I may be wrong but it seems the heat increases only when driving.
James Wilson
asked Dec 1, 2017 at 17:55
James Wilson James Wilson
2,992 26 26 gold badges 81 81 silver badges 119 119 bronze badges
Stationary as in when you first start the car, or literally at each stop light the heat stops?
Commented Dec 1, 2017 at 18:53
If you stop, does the heat stop flowing?
Commented Dec 1, 2017 at 19:42
@JPhi1618 stationary when i first start. i timed it today and after 10 minutes it only became a little warm despite being on the hottest setting. again only after a driving for some minutes did it heat better.
Commented Dec 2, 2017 at 2:22
6 Answers 6
I am guessing that you have an air pocket in the cooling system. When the cooling system/ engine was replaced they did not remove all the air. While the car is at idle the coolant flow is insufficient to provide heat. You can prove this theory by placing the car in park and increasing the engine RPM and feel if the heat increases. You need to bring it back to whoever did the work and see if they can “burp” the air out of the system
answered Dec 1, 2017 at 21:26
20.1k 2 2 gold badges 27 27 silver badges 50 50 bronze badges
This. Some vehicles are worse than others. In fact, I owned a 94 Pontiac with a 3100, and it had a coolant bleeding port. It took over 45 minutes of idling and adding fluid to get it bled. Another friend blew his head gaskets because he thought he had enough coolant when in fact he was a gallon low on a similar GM product.
Commented Dec 10, 2017 at 1:43
Once the engine has warmed up, you should get heat from the heater regardless of whether you are moving or not – for the first few minutes after starting from cold you won’t, as engine doesn’t have enough heat in it to heat up the incoming air.
answered Dec 1, 2017 at 18:20
28.9k 8 8 gold badges 56 56 silver badges 109 109 bronze badges
I timed it today, its was about 2c and after 10 minutes despite being on the highest heat setting it was only a little warm and I think the slight heat came after i revved it a little. . i got fed up and just moved off. Might this be suggestive of something other than simply warming up from cold?
Commented Dec 2, 2017 at 2:28
The problem is not what heat setting you use or if you are driving or not. You won’t get warm air if your engine is still cold. Cars warm up slowly when idling and it can take 10 minutes or more depending on outside temperature etc. That’s perfectly normal. Especially diesel models get warm even slower.
When you drive, engine uses much more fuel, so it gets warm fast. For example my car does 0.6liters/hour when idling but it uses 6+liters/hour if I am driving 100km/h speed. That is more than 10 times more fuel burned. Therefore engine gets warmer faster.
If you get warm air when engine temperature needle is showing normal temperature. Then everything is fine and you don’t have to worry about this.
answered Dec 6, 2017 at 23:55
Evren Yurtesen Evren Yurtesen
1,208 7 7 silver badges 9 9 bronze badges
Usually there’s a vacuum actuated valve which controls the diversion of coolant into the heater core. It’s possible that the vacuum tube is either loose or leaking, and isn’t able to provide enough vacuum to actuate the valve at low engine speed.
answered Dec 1, 2017 at 21:53
RubberStamp RubberStamp
121 1 1 gold badge 1 1 silver badge 3 3 bronze badges
Yes. If your temperature gauge is steady somewhere in the middle (where it “usually” is), your water pump is likely not pushing enough coolant through your heater core.
Likely causes for this not working are underdriven pulleys (you would have installed such a thing), air in the system, or a failing water pump.
answered Dec 2, 2017 at 0:20
79 3 3 bronze badges
soolus, once there’s more heat the temperature gauge rises to just under half. however you say that’s where it is usually(normally) meant to be but at the same time you say thats suggestive of a problem. seems like a contradiction, if thats where the gauge is meant to be, please clarify. i believe a new water pump was installed with new engine and i dont know of any underdriven pulleys installation. does this suggest their is air in the system?
Commented Dec 2, 2017 at 2:37
At idle RPM in cold winter weather, the engine is not producing enough heat to overcome cooling from the cold outside ambient air temperature.
Assuming a typical 4-cylinder sedan gas engine idling at about 900 RPM, it is firing 15 times per second at a likely lean fuel mix because all it needs to do to maintain that RPM, is overcome the friction of the bearings and the engine accessories.
When you get out on the road, the engine goes up to about 3000 RPM, firing 50 times a second on a rich fuel mixture, so much more heat is being produced.
The heater is likely producing some warm air, but it’s not warm enough to matter to you. If you have the blower on high, the small heater core is trying to heat a huge moving air mass with limited thermal energy. Set the blower on low and it will feel warmer.
Also setting airflow to recirculate will help warm the cabin more quickly, though the recirculated cabin air may also fog and freeze the windows with moisture.
Turning on additional electrical loads like a rear window defroster and the vehicle lights will add load to the engine via the alternator, increasing the idle speed and fuel richness so it produces more heat. This effect will be limited, though, since the defrost heater and all the lights are about 2000 watts, or 2.5 HP of power for an automobile engine likely rated for 90-300 HP.
Slightly pressing the accelerator so it idles at 3000-4000 RPM will also increase the heat output somewhat, but it doesn’t take much fuel to push an engine with no load up to this high idle RPM, so the warming effect is not as great as actually driving down the road at highway speed at this RPM.
Does Car Heating Work with Engine Off?
The answer is: yes, but only for a limited time.
When you turn on your car’s heater, hot coolant from the engine is pumped through a heat exchanger (also known as a heater core) in the passenger compartment. The heat exchanger transfers heat to the air in the passenger compartment, which is then blown out through the vents.
If you turn off the engine, the coolant will continue to circulate through the heat exchanger for a short period of time. This is because the coolant is still hot and there is still some residual heat in the engine. However, as the coolant cools down, the heat output from the heater will gradually decrease.
How long the heater will work with the engine off depends on a number of factors, including the outside temperature, the size of the engine, and the size of the heat exchanger. In general, the heater will work for longer in colder weather and in cars with smaller engines and smaller heat exchangers.
If you need to use the heater for an extended period of time with the engine off, you can purchase a portable heater that plugs into the cigarette lighter. Portable heaters are available in a variety of sizes and price ranges, so you can find one that fits your needs and budget.
Safety precautions
Never use a portable heater in a car that is parked in an enclosed space, such as a garage. This is because portable heaters can produce carbon monoxide, which is a poisonous gas. Symptoms of carbon monoxide poisoning include headache, nausea, dizziness, and confusion. If you experience any of these symptoms, get fresh air immediately and seek medical attention.
Also, never leave a portable heater unattended in a car. Portable heaters can overheat and start a fire.
Conclusion
Yes, car heating works with the engine off, but only for a limited time. The heater will work for longer in colder weather and in cars with smaller engines and smaller heat exchangers. If you need to use the heater for an extended period of time with the engine off, you can purchase a portable heater that plugs into the cigarette lighter. However, be sure to follow the safety precautions listed above.
Does the Car Heater Work With the Engine Off? Get Answers!
Are you wondering if your car heater can keep you warm during the winter without running the engine?
It’s a common question, and in this article, we’ll explore whether car heaters work effectively when the engine is off.
Discover the factors affecting their performance and the potential risks involved. Stay cozy on the road with our insights.
Does the Car Heater Work With the Engine Off?
Car heaters relies on the engine’s warmth to operate. Without the engine running, the heater won’t produce heat, though the fan may still blow air. Starting the engine allows the coolant to warm up, providing heat inside the vehicle.
How Car Heaters Draw Heat from the Engine
Here are the some possible way how Car Heaters Draw Heat from the Engine:
Engine Heat Transfer
The engine consists of a range of metal components that are always in motion, rubbing against each other. It generates heat through friction.
The engine burns fuel, producing heat as well. If you overheat the engine, it can be damaged and even catch fire. That implies that it has to be cooled as it gets heated.
Role of the Coolant
The cooling system includes a water pump, a radiator, hoses, and a thermostat.
The coolant is pushed through the hoses that link the engine and the radiator by the water pump.
The radiator is a large metal device consisting of numerous fans and tubes. Normally, it is situated at the front of the car and receives fresh air from outside.
Coolant cools down as heat is transferred to the air through the radiator. A thermostat is a valve that controls the coolant flow between the engine and the radiator.
It opens when the engine is hot and shuts when it is cold.
Heat Flow Inside Your Car’s Engine
Coolant flows in a loop from the engine to the radiator and back to the engine.
The engine heats the coolant, which then flows to the radiator when the engine is running.
The coolant flows to the radiator and gets cooled down; thereafter, it returns to the engine. The engine is still running, and this cycle repeats continuously.
Engine’s Heat from Fuel Burning
When you accelerate, the fuel burns and powers your car’s engine. It is kept in a tank and fed into the engine by the fuel pump and injectors. In the cylinder chamber, the fuel mixes with air and is pressed together with the piston.
The fuel-air mixture is ignited by a spark plug, causing an explosion and pushing the piston down. This spins a crankshaft; this in turn rotates a driveshaft to spin a wheel.
The engine consists of a multitude of cylinders that fire sequentially, resulting in a smooth and consistent action.
Heater Core’s Functionality
The heater core is connected to the cooling system by two hoses: a coolant inlet, which supplies hot coolant to the engine, and a coolant return, which takes cold coolant away from the radiator.
The heater core is comprised of many small tubes that are wrapped in thin metal fins.
As a result, the coolant is cooled down, and it takes up more space when it contacts the air through these fins.
When you switch on the heater, a valve opens, releasing hot coolant into the heater core. The air becomes warm and is pumped into your car’s interiors by a fan passing through the fins.
Regulating Temperature
By adjusting the knob or button on your dashboard, you can control the warmth in your car’s interior.
The hot coolant flow into the heater core is controlled by this knob or button. Turn it up, and it gets hotter, as opening the valve releases more hot coolant.
Read About: What Does A Choke Do On An Engine? Find Out Now!
If you want to lessen the heat, you turn it down, which closes the valve more, thus letting less hot coolant.
Transfer of Residual Engine Heat
When you stop your engine, it stops burning fuel and warming up. The remaining heat is in the engine and in the coolant.
This heat is gradually released into the surrounding air over a period of time.
After you turn off your car’s engine, the heater core can still use some residual heat to warm up your car’s interior for a while.
Factors Affecting Car Heater Performance with Engine Off
Several factors that affect car heater performance when it’s engine off:
Ambient Temperature Influence
Ambient temperature, or that of the air outside your car. It determines the rate at which your engine and your coolant lose heat after shutting off your engine.
The colder the air temperature, the faster your engine or coolant will dissipate its heat to the heater core.
As the ambient temperature is higher, more heat reaches your engine and coolant, and less is diverted to cool your heater core.
Coolant Levels and Heater Efficiency
It refers to the amount of coolant that is available in the cooling system. It is the degree to which your coolant can carry heat from your engine to your heater core.
The more heat your coolant carries, the higher the coolant level. The better your heater core can warm up the air.
When the coolant level goes down, it means it has less heat to carry, and thus the heater core will not be able to warm the air as well.
Age and Condition of the Heater Core
These are the factors that determine the efficiency of heat transfer from the coolant to the air through the heater core.
They determine the amount of heat that the heater core loses or gains as it moves through it. The heat loses and gains in the heater core depend on how new and cleaner it is. Therefore, the more efficiently it heats up the air.
The older and dirtier the heater core becomes, the more heat it loses or gains, and the less efficient the heating of air becomes.
Thermostat Operation and Impact
The thermostat is a valve that controls the flow of coolant from the engine to the radiator.
It influences how hot or cold the coolant is when it reaches your heater core. When the engine is hot, the thermostat opens, and when the engine is cold, it closes.
This is done for the engine to keep its temperature at a constant and ideal level.
But when you switch off your engine, the thermostat may not close completely, allowing some coolant to flow to the radiator to cool.
This minimizes the amount of hot coolant available for the heater core.
Air Pockets in the Cooling System
By cooling system, the meanings are trapped air pockets commonly called the bubbles. These elements affect the circulation of your coolant in the cooling system.
You can experience the formation of air pockets when you refill the cooler, drain the coolant, or have a leak in the cooling system.
Block or impede the flow of coolant, preventing it from reaching the heater core or reducing its temperature, causing air pockets. This reduces the performance of your car heater.
Heater Control Valve Functionality
The valve that controls the coolant flow into the heater core is called a heater control valve.
It determines how much hot or cold coolant enters the heater core according to your temperature choice.
When you want more heat, the heater control valve opens, and when you want less, it closes.
However, the heater control valve sometimes gets stuck or malfunctions and doesn’t open or close as it should.
This results in either an excess or insufficient amount of coolant reaching the heater core and thus its ability to heat or cool the air.
Read About: Does Revving the Engine in Park Damage It? Find Out Now
Ventilation and Airflow Restrictions
Airflow and ventilation are what will determine the efficiency of warm air from a heater core or cool air reaching your car’s interior. They determine how cozy you feel in your car.
The fan speed, the vent position, and the window status determine ventilation and airflow. With an increase in fan speed, more air would be blown through the heater core into your car.
As the fan speed decreases, less air is forced through the heater core and into your car.
The vent position determines where the air is directed: on your feet, on your face, or both.
You decide whether to let in fresh air or keep warm air inside the window. If there is no adequate ventilation or airflow, you may never know the full effect of your car heater.
Residual Heat Retention
Retained heat in your car is the ability to hold warmed air generated by the heater after the engine is turned off, prolonging the warmth period without external energy.
For example, there is heat transfer by walls, windows, and doors, which is prevented by the insulation effectiveness of the car.
Secondly, air circulation is affected by the size of the car, while heat conduction is determined by the materials of the car.
Finally, sunlight absorbs These elements combine to determine how many times occupants can stay warm in the car without resorting to heating.
Risks and Precautions: Using a Car Heater without the Engine
Here are the risks and precautions when using a car heater without the engine:
Battery Drain Concerns
One of the main risks of using a car heater without an engine is that it can drain your battery.
The car heater uses electricity from the battery to power the fan and the heating element.
If you use the heater for too long, you might end up with a dead battery. This means that you won’t be able to start your car, and you might need a jump start or a tow truck.
According to some experts, using the car heater for 10 minutes can reduce your battery charge by 5%. That might not seem like a lot, but if you do it often, it can add up.
Wear on Electrical Components
Another risk of using the car heater without the engine is that it can wear out your electrical components.
The car heater is designed to work with the engine running, which provides a steady supply of electricity.
When you use the heater without the engine, you are putting more stress on the electrical system.
This can cause overheating, short circuits, or damage to the wires and fuses. Over time, this can affect the performance and reliability of your car.
Reduced Heat Output
You might also notice that using the car heater without the engine does not produce enough heat. This is because the car heater relies on the engine to generate heat.
The engine burns fuel and creates hot exhaust gases, which are used to heat up a liquid called coolant.
The coolant circulates through a device called a radiator, which transfers heat to the air.
The air then passes through a fan and a heating element, which warm up the air inside the car.
When you use the heater without the engine, there is no hot coolant or exhaust gas to heat up the air.
The only heat source is the heating element, which is not very powerful. As a result, you might feel cold and uncomfortable in your car.
Risk of Incomplete Combustion
Some cars have a different type of heater that does not use electricity or coolant. Instead, they use fuel to create heat.
These heaters are called fuel-fired heaters or auxiliary heaters. They work by burning fuel in a small chamber and blowing hot air into the car.
Read About: Is It Okay To Drive With Check Engine Light On? Expert Views
They can be used without the engine, but they have some drawbacks. One of them is that they can produce incomplete combustion.
Incomplete combustion means that not all of the fuel is burned completely, and some of it escapes as smoke or gas.
This can create harmful emissions, such as carbon monoxide, which can be dangerous for your health and the environment.
Potential Carbon Monoxide Exposure
Carbon monoxide is a colorless, odorless, and tasteless gas that can be deadly if inhaled. It can cause headaches, dizziness, nausea, confusion, and even death.
Carbon monoxide can come from incomplete combustion of fuel-fired heaters or from leaks in the exhaust system of your car.
If you use these heaters without proper ventilation or maintenance, you might be exposed to carbon monoxide in your car.
This can be very risky, especially if you fall asleep or lose consciousness in your car.
Over-reliance on Residual Heat
This may be true for some people who claim that there is no need to use any heater inside the car.
They may depend on the residual heat generated when you shut down your engine in your car.
It can maintain heat in your car for a bit, but eventually, residual heat will escape through windows, doors, and vents.
Unless it’s really cold, the remaining heat cannot keep you warm for very long.
Too long of a leave-off on heating your car may therefore lead to the freezing of your windows, if not your pipes.
Reduced Lifespan of Heater Components
Lastly, any heater should be avoided from operating without an engine.
Heaters consist of a number of items that can eventually get worn by friction, corrosion, or fatigue.
They can be stressed more using them, causing them to be damaged faster. It may, for instance, burn out or overheat a fan when an electric heater is turned on, without the engine running.
Leaking, clogging, or cracking in the chamber or nozzle on a fuel-fired heater is a result of not maintaining the device properly.
These problems could reduce the efficiency of your heater, or it would stop functioning completely.
FAQs about Your Car Heater
Can car heaters provide sufficient warmth with the engine off?
Yes, car heaters can provide some warmth with the engine off, but their effectiveness is limited compared to when the engine is running.
Is it necessary to run the car engine to have heat in the cabin?
Yes, running the car engine is necessary to generate optimal heat for the car’s heating system.
How long does it take for a car heater to warm up?
The time it takes for a car heater to warm up can vary, but it typically takes a few minutes for the vents to start blowing warm air.
Do car heaters work when the vehicle is stationary?
Car heaters can work when the vehicle is stationary, but the level of heat output may be lower compared to when the vehicle is in motion.
Does using a car heater without the engine strain the battery?
Yes, using a car heater without the engine can drain the battery, potentially causing it to go dead over time.
Can car heaters pose a risk of carbon monoxide exposure?
Yes, using certain types of car heaters without proper ventilation can lead to potential carbon monoxide exposure, which is dangerous to health.
Are there risks to relying solely on residual heat in the car?
Yes, relying solely on residual heat in the car after turning off the engine may not provide sufficient warmth in extremely cold conditions, and it can lead to issues like frozen windows.
Final Thoughts
A car heater’s efficacy diminishes without the engine’s heat.
Factors like ambient temperature, coolant levels, and the heater core’s condition impact its performance.
However, using it without the engine poses risks, including battery drain, reduced heat output, and carbon monoxide exposure.
While it can provide some warmth, it’s most effective when the engine is running. Regular maintenance ensures a comfortable journey with your car heater.
Al Amin
Welcome to Auto Kits Lab! I am Al Amin, the editor behind Auto Kits Lab (since 2022). James L. Rocha and I run this blog together and breaking down all your queries is just as easy as that. Thanks for stopping by! We are so happy you’re here.
https://nodsauto.com/does-car-heating-work-with-engine-off-2/
