How It Works: Your Car's Heating System - Driving
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When the weather turns cold, few things on your vehicle seem as important as its heater. Its controls may be on the dash, but the heart of how most of them work begins inside the engine with its cooling system.
Article contentRegular maintenance on that system not only benefits the engine, but can keep your vehicle’s heater in good condition as well.
Article contentArticle contentAn engine generates so much heat from combustion and friction that if it isn’t continuously cooled, it can suffer serious damage. Virtually all modern vehicle engines are liquid-cooled, using water blended with antifreeze to reduce corrosion and keep it from freezing.
Article contentAdvertisement 1Story continues belowThis advertisement has not loaded yet, but your article continues below.Article contentThe coolant is pumped through channels in the engine, called water jackets, where it absorbs heat. It then travels into the radiator where it cools down before going back into the engine in a continuous loop.
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Some of the hot coolant makes a detour from the engine through a water valve and over to the heater core. This is a miniature version of the radiator, with tubes for coolant circulation and cooling fins to dissipate the heat.
Article contentArticle contentWhen you turn on the fan, a blower motor sends the air warmed by the heater core into the cabin. To regulate the temperature, small “blend doors” open or close to regulate how much hot or cold air enters the cabin from the heater core or air conditioning unit. There’s also a flap that regulates how much fresh air comes into the climate system from outside.
Article contentSetting the system to “Recirculate” closes this outside flap, and the climate system receives only inside air to be heated or cooled. This helps it to reach the desired temperature quickly, and can also prevent outside odours from getting in (flip it closed quickly when you see the dead skunk up ahead!), but leaving it in that position too long can build up condensation and cause the windows to steam up. If too little fresh air comes in, it can also create higher carbon dioxide levels, which can make you drowsy.
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If your vehicle has automatic climate control, it uses sensors to monitor the cabin, and then opens or closes the blend doors and outside flap as needed to maintain the temperature you’ve set. Dual-zone systems, which allow driver and passenger to set different temperatures, operate individual blend doors on either side of the dash.
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A series of flap doors also determines where the air goes, and these open or close to adjust the airflow when you change the vent modes between the floor, dash, or defroster vents.
Article contentOf course, your heater doesn’t blow hot air as soon as you start the car. The colder it is outside, the longer it takes before you start to feel the warmth – and that’s primarily because of the thermostat, a temperature-sensitive valve located in the cooling system between the engine and the radiator. Engines have an ideal operating temperature that’s generally between 90 and 104 degrees Celsius; below that, they don’t run as efficiently and they emit more pollution. To get there as quickly as possible, the thermostat closes to keep the coolant inside the engine from travelling through the entire cooling system. Once the engine warms up enough, the thermostat opens. That now-warm coolant circulates into the heater core to keep you toasty.
Article contentCoolant eventually breaks down and should be flushed out and replaced according to your vehicle’s maintenance schedule. If it’s ignored for too long it can cause rust and corrosion build-up in the system, which can clog the heater core’s inner tubes and restrict the flow of coolant through it – and that means no heat. If there’s a problem with the heater core, you might also see coolant dripping from below the dash onto the passenger side of the floor, or notice a strong, sweet smell. Prevention is always better than the cure. Many heater cores are buried deep in the dash, and while the part itself isn’t all that expensive, pulling everything apart to replace it drives up the labour cost.
Article contentAdvertisement 2Story continues belowThis advertisement has not loaded yet, but your article continues below.Article contentIf your heater isn’t heating, other problems can include a failed blower motor, or defective actuators that aren’t operating the blend doors correctly. Other causes can be a faulty engine thermostat, leaks or low coolant level in the cooling system, or a malfunctioning water pump, all of which will also affect the engine’s operation. Many vehicles include a cabin air filter, and if it’s clogged, it can reduce the heater’s efficiency. Most filters are located near the glovebox and your owner’s manual will show you how to replace it.
Article contentLacking a hot engine, most electric cars use electric heaters. Since this cuts into the battery’s range, most can be pre-warmed (or pre-cooled) while they’re charging from a wall outlet. Some include heated seats and steering wheel, and while these are energy hogs, drivers tend to turn down the even-more-power-hungry cabin heater if their hands and butts are warm. Nissan has also developed an energy-efficient heat-pump system for cabin heating and cooling in its battery-powered Leaf. Heaters have been around for a long time, but automakers are always looking at ways to improve them.
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Jil McIntosh specializes in new-car reviews, auto technology and antique cars, including the two 1940s vehicles in her garage. She is currently a freelance Writer at Driving.ca since 2016Summary
· Professional writer for more than 35 years, appearing in some of the top publications in Canada and the U.S.
· Specialties include new-vehicle reviews, old cars and automotive history, automotive news, and “How It Works” columns that explain vehicle features and technology
· Member of the Automobile Journalists Association of Canada (AJAC) since 2003; voting member for AJAC Canadian Car of the Year Awards; juror on the Women’s World Car of the Year Awards
Education
Jil McIntosh graduated from East York Collegiate in Toronto, and then continued her education at the School of Hard Knocks. Her early jobs including driving a taxi in Toronto; and warranty administration in a new-vehicle dealership, where she also held information classes for customers, explaining the inner mechanical workings of vehicles and their features.
Experience
Jil McIntosh is a freelance writer who has been writing for Driving.ca since 2016, but she’s been a professional writer starting when most cars still had carburetors. At the age of eleven, she had a story published in the defunct Toronto Telegram newspaper, for which she was paid $25; given the short length of the story and the dollar’s buying power at the time, that might have been the relatively best-paid piece she’s ever written.
An old-car enthusiast who owns a 1947 Cadillac and 1949 Studebaker truck, she began her writing career crafting stories for antique-car and hot-rod car club magazines. When the Ontario-based newspaper Old Autos started up in 1987, dedicated to the antique-car hobby, she became a columnist starting with its second issue; the newspaper is still around and she still writes for it. Not long after the Toronto Star launched its Wheels section in 1986 – the first Canadian newspaper to include an auto section – she became one of its regular writers. She started out writing feature stories, and then added “new-vehicle reviewer” to her resume in 1999. She stayed with Wheels, in print and later digital as well, until the publication made a cost-cutting decision to shed its freelance writers. She joined Driving.ca the very next day.
In addition to Driving.ca, she writes for industry-focused publications, including Automotive News Canada and Autosphere. Over the years, her automotive work also appeared in such publications as Cars & Parts, Street Rodder, Canadian Hot Rods, AutoTrader, Sharp, Taxi News, Maclean’s, The Chicago Tribune, Forbes Wheels, Canadian Driver, Sympatico Autos, and Reader’s Digest. Her non-automotive work, covering such topics as travel, food and drink, rural living, fountain pen collecting, and celebrity interviews, has appeared in publications including Harrowsmith, Where New Orleans, Pen World, The Book for Men, Rural Delivery, and Gambit.
Major awards won by the author
2016 AJAC Journalist of the Year; Car Care Canada / CAA Safety Journalism award winner in 2008, 2010, 2012 and 2013, runner-up in 2021; Pirelli Photography Award 2015; Environmental Journalism Award 2019; Technical Writing Award 2020; Vehicle Testing Review award 2020, runner-up in 2022; Feature Story award winner 2020; inducted into the Street Rodding Hall of Fame in 1994.
Contact info
Email: [email protected]
Linkedin: https://www.linkedin.com/in/jilmcintosh/
Twitter: https://twitter.com/JilMcIntosh
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