Why Doesn't My Car Have Heat?

күнү жарыяланды 2020-ж., 14-окт.
Көрүүлөр 134 603

How To Diagnose & Fix A Car That Doesn't Have Any Cabin Heat (Broken Heater)
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My car's heater is broken, how do I fix it? When a car isn't producing any cabin heat, there are many different parts of the car that could be causing this to happen. This video looks at diagnosing a broken heater. We'll talk about engine coolant, heater cores, water pumps, HVAC controls, HVAC fans, thermostats, radiators, and all the ins & outs and best practices when looking to understand why and how your heat doesn't work in your car.
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Engineering Explained
  • 春樹ニコラス


    Ай мурун

    yoo.... i'm searching how to reduce overheat and found this.

  • Isaac Watson

    Isaac Watson

    Ай мурун

    I need more videos about your yellow Miata and how it's doing with the Supercharger please!

  • Jannie Kirsten

    Jannie Kirsten

    2 ай мурун

    That's not a "thermostat", it's a "therostatic valve".



    2 ай мурун

    Clean out heater core
    Check for leaks
    Check for bad water pump
    Check for low coolant

  • R Gunness

    R Gunness

    2 ай мурун

    Great collaboration guys

  • Nopleaseno


    3 ай мурун

    Changed everything on my friends Dodge Journey, no heat!!! New hoses, new heater core, new thermostat, new blend door actuator. Everything but the rad. The rad was the problem. Flushed the system more then 4x. But the problem was the gummed up pieces in the rad. They were so big they didn’t break down while flushing and would settle after putting the system all back together causing blockages. New rad and more flushes later, good to go. You likely understand the issue if you’re a journey owner.

  • Isaac Lwanga

    Isaac Lwanga

    3 ай мурун

    My car bows heat but the central vent doesn't blow ,what could be the problem ?

  • Marco Roman

    Marco Roman

    3 ай мурун

    Wasted a lot of time just to check the heating why do you need check the exterior your a master tech doing lube tech checklist smh

  • Nope


    3 ай мурун

    Step 1 should be to make sure there's coolant in the radiator. Without that, there won't be any heat moving around.
    (I have found cars without any coolant....)

  • y e t visuals

    y e t visuals

    4 ай мурун

    I have a diesel civic 2.2l 2007, And it's so confusing to find all of that.

  • Luis E. Rivera

    Luis E. Rivera

    4 ай мурун

    Also something so simple that I’ve seen people doing, they turn off the A/C button which turns on the compressor, which helps cool AND heat up the interior, much like a Heat Pump HVAC system.

  • ClayZ


    4 ай мурун

    Number one is check for coolant level. You may be damaging the engine internally by running it without coolant!

  • Izzat Fauzi Mustafa

    Izzat Fauzi Mustafa

    4 ай мурун

    You need to set up a bonfire inside the car if the HVAC's heating function doesn't work. 😉

  • Thomas Kinkade

    Thomas Kinkade

    4 ай мурун

    Honestly, Electric cars have HVAC and blow dryers exist. It's cool to use the waste heat from an engine to heat the car but that shouldn't be the only system.

  • Hashim Alawneh

    Hashim Alawneh

    4 ай мурун

    I would discuss the more common causes first. How likely is it that the blend door is stuck? 🤦🏻‍♂️

  • Aaron Jaggan

    Aaron Jaggan

    4 ай мурун

    Me: my ac isn't working.
    Mechanic: sir u did not pressed the ac button.

  • Chuckiele


    4 ай мурун

    And if youre engine cant get up to temperature even though the thermostat works, then you might have a diesel :D

  • eduardo paz

    eduardo paz

    4 ай мурун

    Thank you Jason for all the Details about Car Heat / it is true A Car without Heat is a Pain specially Up North / Here in Miami is ok we only get a few moths of cool weather .

  • Richard DuBois

    Richard DuBois

    4 ай мурун

    What if I'm driving a 1960 Chevrolet Corvair ? That vehicle had an air cooled engine and a gasoline heater...the only year of that type of cabin heating source.

  • Adrian Cigher

    Adrian Cigher

    5 ай мурун

    0:43 I liked that

  • Sergeant


    5 ай мурун

    Dealer Technician (mechanic)? Not sure you'd want to admit that. In Australia, the dealership is the last mechanic you want to take your pride and joy to!

  • Kyle Spangenberg

    Kyle Spangenberg

    5 ай мурун

    There is a clicking noise in my 04 explorer when I try to turn on the heat, but I get no heat. Any ideas what's causing that.

  • Neptune Vibe

    Neptune Vibe

    5 ай мурун

    Part time technician full time hobo.

  • Cody Schleiger

    Cody Schleiger

    5 ай мурун

    You NEVER want to have to replace a blend door. There usually located in the dash. Expansive $ & time consuming

  • starfoxacefox


    5 ай мурун

    There also heater valves which I see all the time with VAG cars

  • FlashGeiger


    5 ай мурун

    I had a coworker come in on a Monday after spending all weekend changing the heater core on his car. After that ordeal he maintained that if you go to the car assembly plant and went the very start of the line, there was a guy standing there holding a heater core that they then built the car around.

  • JK Brown

    JK Brown

    5 ай мурун

    1907 - first enclosed passenger compartment. Still took 23 years before the engineers realized they had a big source of hot water to use for heating in winter.

  • Davis Byer

    Davis Byer

    5 ай мурун

    Fun fact heat for most small piston airplanes (like the Cessna 172) comes from a simple shroud around the exhaust pipe!

  • Xander Percy

    Xander Percy

    5 ай мурун

    What infrared thermometer do you use? I use mine almost daily for synchronizing motorcycle carburetors based on header pipe/head block temp but I find myself doubting the readings on occasion... It's just a cheap Amazon unit.

  • FromRoselawn74


    5 ай мурун


  • TheMattbrownbill


    5 ай мурун

    The designers of my car decided a temperature gauge was not necessary, so now I need to use an OBD2 tool to see if the thermostat has failed. Thanks GM.....

  • Patsfan11


    5 ай мурун

    You guys are talking about a lot of stuff but 95% of the time that I have had no heat, it was the thermostat stuck open or closed

  • briansmobile1


    5 ай мурун

    Charles, your shop looks SO GOOD!!! Jason, nice catch on the coolant leak catch. That's the most common problem I see come in.

  • khasmir666


    5 ай мурун

    It's really awesome to have a cooling thermostat fail and stay closed in mid summer...
    Engine was overheating but we managed to limp home by turning the heating to max and having the windows open in +30°C temperatures outside. So apparently the coolant was not going to the radiator but was feeding the heating system in that old Ford Mondeo?

  • MotoCat


    5 ай мурун

    My worst experience of driving without functional AC was actually on a motorbike. The bike had an in built ambient temp sensor which was accurate to a few degrees give or take for wind/sun. The sensor itself is inside the dash and shielded from direct headwinds, engine heat, sun etc so it was pretty good.
    One day, it display reads 50 degrees and starts flashing at me because it reached the limits of the sensor and going further could damage it.
    Now you might be thinking pfft, only 50f? that's not cold at all! But you see.. it wasn't 50f, but 50C
    Middle of summer in Australia, ~10km/h in heavy traffic, textile breathable jacket doing nothing because no wind.. and the sun beaming down so much parts of the road surface were literally melting and tearing the rubber off shoes.
    I was out there barely 20 mins and nearly passed out from the heat.. don't know what the true temperature was on the road either due to the thermometer capping out.
    I envy all you peeps that actually have a reason to use heating controls, as I've never used them in any car I've owned

  • T B

    T B

    5 ай мурун

    While traveling in Munich, Germany I was driving my cousins VW Rabbit in summer. Returning to the city, the highway was clogged with traffic, forcing us to slow down.
    I noticed the car engine temp was suddenly rising quickly. While stuck in traffic, this was going to end badly, quickly.
    I turned on the cabin heater to full heat. My cousin was annoyed until I pointed out that this was the only thing keeping the car from overheating in traffic.
    This was a temporary reprieve but it was enough to get us home without further mechanical mishap. Next day the car was taken for service, problem solved, though I did not hear what the ultimate cause of the problem was.

  • J


    5 ай мурун

    too much of my lift was in a car with no heat lol

  • Niels Onderbeke

    Niels Onderbeke

    5 ай мурун

    Both you guys are awesome

  • datsuntoyy


    5 ай мурун

    2:00 I was an aircraft mechanic for a while and we frequently got RO's from pilots for inoperational units. You'd be amazed how many RO's were signed off as "does not work in the 'OFF' position". We can only imagine the razzing they got back in the ready room.

  • tallll70


    5 ай мурун

    Please make video about why my car is forced to cool when i'm heating in windshield mode, cause i wanna know...my theory is, so they don't have to explain defrosting and it just does it on it's own

  • Ora Labora

    Ora Labora

    5 ай мурун

    do one with EVs and PTC and/or heat-pumps, please!

  • Tom Wiech

    Tom Wiech

    5 ай мурун

    We gotta hear about the tuatara from you. How did they hit 331 when tires aren't even supposed to handle 300

  • Ulf Asplund

    Ulf Asplund

    5 ай мурун

    Great video, looking at it in the morning with mid 20s (F) outside and my Tesla model 3 is warming up. :-)
    Yesterday I found an unopened container of antifreeze and gave it to my neighbor, who might need it.

  • Tariq Mehtab

    Tariq Mehtab

    5 ай мурун

    No videos on suspension geometries as of yet.
    An idea.
    Start from basic leaf springs.
    Please explain why the 2 joints in leaf spring setup of Daihatsu Hijet/Piaggio porter are uneven. Also explain the dynamics.

  • kartik chaudhari

    kartik chaudhari

    5 ай мурун

    Please explain SSC tuatara.

  • MilanovicChiller


    5 ай мурун

    Make a video about The Tuatara! It just set a record with ridiculous low drag

  • معتز يحيى

    معتز يحيى

    5 ай мурун

    General question
    When you are on a low rpm that means that the throttle isn't fully opened, and this mean that the cylinder wont take all the air that it need, so the compression ratio of the car will be achieved only on high rpm only when the throttle is fully opened, and also the turbo charger or the super charger isn't usefull on low rpm when throttle is partially open
    Am I right?

  • Nick Neathery

    Nick Neathery

    5 ай мурун

    I had this problem a few years ago. Water pump was about to seize on my car.

  • vhjioa


    5 ай мурун

    Thanks for an awesome video from 2 awesome fellas! Your teaching makes it stick to my head :))

  • mmmbetter55


    5 ай мурун

    Yo @Engineering Explained, can you do a video on exhaust wrapping and why / whether it does anything?

  • Ghost Shadow

    Ghost Shadow

    5 ай мурун

    I had a 1978 subaru GL sedan when outside temperatures got colder than -30F at highway speeds the engine temperature bottomed out, the old 1600cc boxer engine had too much surface area.
    coolant level will gradually drop due to EVAPORATION.
    old engines the thermostat mounted to the engine block.

  • RedAssassin274


    5 ай мурун

    Nice nice, a dodge ram's AC controls. I thought I recognized it so I had to rewind again lol. 1:14

  • Tim Bryan

    Tim Bryan

    5 ай мурун

    Florida drivers: why make car hot?

  • magnulof


    5 ай мурун

    Hi, I was just made aware of something called Evans which is a cooling liquid replacement. Could you please do a take on that?

  • Vorch


    5 ай мурун

    Went through several blend door actuators on my Mk 7 GTI within the first couple of years of ownership. Got rid of the car before something more expensive broke out of warranty.

  • R. Fair

    R. Fair

    5 ай мурун

    I have unrelated questions: Does the shape of a car's engine's compartment affect the aerodynamics of a car? Does it cause a car to hold in more heat if shaped a certain way? As moving air flows through the grill, under and around a car, some of that air passes through the engine compartment. When the air exits, does the shape of the compartment causes some lift under the car? Does it cause some air restrictions that affect the car as a whole? What if a skid pad (or something similar) was installed, would that help with better air flow coming from the engine compartment? In your opinion, if a car had more components in its compartment (limiting air flow in the engine compartment), would that be better or worse for heat dissipation and aerodynamics? I also wanted to know if there are air pockets in the engine compartment without proper air flow could cause the engine to stay or to get warmer. I am thinking that if a compartment was changed to an unconventional shape, it would help in these areas. Would you consider making a video addressing these issues mentioned? I ask these questions because of a home project I am considering. Thanks so much - love your content!! Keep it up! You've helped me understand other areas and systems here.

  • Flames 472

    Flames 472

    5 ай мурун

    do an update video on hydrogen fuel cell cars (if they still exist)

  • Nick's Stuff

    Nick's Stuff

    5 ай мурун

    True fact: my brand new car in India didn't come with a heating system at all (had AC, though)

  • Koppakuoriainen


    5 ай мурун

    Do you have any tips on reading material (books/forums, etc..) about engines? I feel like i want to take my knowledge to the next step.

  • bonob0123


    5 ай мурун

    Jason, do a video on how the Cyan Concept makes 500+ hp from a 2L 4cylinder engine. thats crazy.



    5 ай мурун

    🤔 could you explain freevalve?

  • G Man

    G Man

    5 ай мурун

    Guess advanced couldn't afford the cheapest solution firstly, the blower resistor. . .

  • Warren Puckett

    Warren Puckett

    5 ай мурун

    Cars from the sixtys and seventys always had some heat, if there was enough coolant. Even if the fan quit. Even in weather below freezing I would turn the fan off once the car cabin got warm. If got too warm just crack the vent window. Don't know what one of those is well gone because cheaper to make a door without them. Oh and you could move at freeway speeds in them without buffeting with any or all windows down a little or all they way down. There was no electronic gimmick to break. Not saying could not be broken. My sisters approach was good at breaking them. She moved the hot/cold floor defrost several times during a single drive. This was replaced by those electronic climate controlled gimmicks that are so much fun repair and fix. And prone to break early and often.

  • Paulus Hamundjebohr

    Paulus Hamundjebohr

    5 ай мурун

    Review the 2020 land rover defender...

  • Surfer Dude

    Surfer Dude

    5 ай мурун

    Could you explain how the heaters in the original VW Bug worked (or more often didn't work)?

  • C Riley

    C Riley

    5 ай мурун

    Most of the time no heat is from a clogged heater core and it takes 5 minutes to fix.

  • H. R. Lawrence

    H. R. Lawrence

    5 ай мурун

    Video Suggestion: Why don't Car Manufactures make car power systems like Earth Movers?
    Using the engine as an electric generator and supply power to the wheels with electric motors.
    Ex.: Terex MT 6300AC - The vehicle is equipped with a four-stroke diesel engine, with 20 cylinders powering an AC electric alternator,
    which in turn supplies power to the electric motor fitted at each side of the rear axle.

  • Jey Moonrise

    Jey Moonrise

    5 ай мурун

    I clicked this video because I recognized the climate control panel in the thumbnail and learned something interesting.

  • evilpeach2


    5 ай мурун

    Vacuum leaks

  • Gacheru Mburu

    Gacheru Mburu

    5 ай мурун


  • jakespeed63


    5 ай мурун

    As a veteran professionally trained technician, it’s refreshing to see and listen to 2 intelligent YouTube hosts. Tired of half ass, cavemen gear heads clogging up this media

  • Федя Поповцев

    Федя Поповцев

    5 ай мурун

    Great video! I would love to see a series of videos about diagnostics of different car systems and mechanisms by you both!

  • Timothy Ortiz

    Timothy Ortiz

    5 ай мурун

    Cause it's a piece of garbage!

  • Dakota Lally

    Dakota Lally

    5 ай мурун

    That is super interesting about the colorblindness issue in temperature control. About 95% of the faucets I have ever used, hot is on the left, cold on the right. Every temperature dial like that, cold on the left. I was taught a standard for salt/pepper shakers when working in a restaurant for ADA purposes: pepper left, salt right. They also have different hole patterns.
    Interestingly, my shower is plumbed backwards, cold on the left, hot on the right. Seriously though, the basic car temperature dial is totally lacking for the colorblind. There is no C or H like a faucet. I do abhor the digital displays/automatic systems though, I prefer manual controls.

  • Calculated Risk

    Calculated Risk

    5 ай мурун

    My car gets no heat in super cold weather (-10F and below) because smol engine. Turn the heat up and I can watch the coolant temperature drop from 185 to 155 before I have to turn off the heat. (My coolant temperature gauge is installed before the radiator inlet, of course).

  • MWB Gaming

    MWB Gaming

    5 ай мурун

    Come to Australia and try to find an old Commodore with working AC
    its a hot ass country yet no-one gets their car AC fixed when it breaks

  • eric chen

    eric chen

    5 ай мурун

    Jason, Could you talk about the topic about the commonality and difference of automotive engines and aircraft piston engines?

  • IFearlessINinja


    5 ай мурун

    EE 10 years ago: I'm going to be a mechanical engineer and change the world for the better!
    Now: Thumbnail picture

  • jimmyguy428


    5 ай мурун

    "PARTS" drinking game...........aaaand I'm dead!

  • R Chelvam

    R Chelvam

    5 ай мурун

    Thank you! I have a 2003 mk4 VW Jetta. Heat went out years ago, BUT I'm near Houston TX, so just drive with a jacket on for 2 months per year. 😄 Yeah, in almost 18 years I've already been through 3 thermostats, a new coolant reservoir tank,... AND all that cheap foam dried and pieces blew out the AC into cabin. Hey, the AC is still ice cold, it runs fine, and its paid off years ago. I'm keeping her. 👍

  • Luca Milazzo

    Luca Milazzo

    5 ай мурун

    Great video, thanks

  • Noukz


    6 ай мурун

    Question: If you want to heat up the engine coolant fluid quickly, is ti better to keep the temperature dial on hottest or coldest setting?

    • Maksim Ghyvoronsky

      Maksim Ghyvoronsky

      5 ай мурун

      Coldest! 100%. And by this I mean you turn the AC on and with all the systems running cumulatively this will cause all of the other fluids to heat much quicker

  • JMise


    6 ай мурун

    This reminds me of the one time I was driving an old Peugeot 309 during a very cold winter night. I glanced at the temperature knob and it was roughly at the middle. I cranked it all the way up and it didn't help at all. After some time the windshield started to freeze up. The next day I realized that the Peugeot geniuses had placed the cold on the clockwise direction and heat on the anticlockwise.

  • Akio_ 2003

    Akio_ 2003

    6 ай мурун


  • Hey It's Drew

    Hey It's Drew

    6 ай мурун

    Jason puts the dials to hot as if it's going to help anyone (besides himself) lol

  • Darshan Singh

    Darshan Singh

    6 ай мурун

    A follow up video addressing different methods for each symptom would be helpful! My 2010 focus had no heat at idle. Revving it for 30 seconds and idle 30seconds, off 1 min. Repeat 3-4 times (while engine is up to temp). Helped me remove the trapped air in my system! The root of this problem could be a leak..

  • Bob B

    Bob B

    6 ай мурун

    Has he done any videos on steam engines ? If not it would be fun to see.

  • Rundllx32


    6 ай мурун

    VW's have the heatercore integrated in the small cooling circuit. Also it isnt the highest point in that small circuit. the head is. If you have a thermostat failure where its stuck close you can save your car by putting the heater on max with the fan on full speed. This way you can extract a good amount of heat from the coolant.

  • Wollie


    6 ай мурун

    Just route the exhaust into the cabin... duh...

  • Perpetual Grin

    Perpetual Grin

    6 ай мурун

    Having had a motorcycle when young, I still get a kick out of the car heater, appreciate it so much.

    • Perpetual Grin

      Perpetual Grin

      5 ай мурун

      @Niels Onderbeke Coldest place on earth, riding a bike in winter is a Young's mans game.

    • Niels Onderbeke

      Niels Onderbeke

      5 ай мурун

      Haha me too! Heavy rain on a winter day, you come home all soaked and frozen. My motorcycle pants also wouldn't go over my boots, so they'd just direct ALL of the rain straight into my boots. And still I miss that motorcycle :)

  • RedstoneWolf


    6 ай мурун

    My car has a secondary water pump (electric) just for heat. So when I’m at a stop light my heat goes away since the rpm at idle isn’t high enough for the main water pump to flow coolant through the heater core. What a weird situation....
    Also of course the replacement auxiliary water pump is $500 😳

  • nickoloes


    6 ай мурун

    Car doesn't have heat... Because it's a vw

  • Brian Cristoni

    Brian Cristoni

    6 ай мурун

    The dent on the miata is really irritating

  • Snehal Ghosh

    Snehal Ghosh

    6 ай мурун

    Expectation: Today I am going to explain you how the octovalve works
    Reality: So the Engine is surrounded by a cooling jacket

  • Daniel Chmiel

    Daniel Chmiel

    6 ай мурун

    Ah yes, a third gen ram climate control panel, I need a new heater core btw

  • Live Life Freely

    Live Life Freely

    6 ай мурун

    I've had about 8 cars that didn't have heat. I've never needed it, I'm from Miami but that's beside the point.

  • Miggy250


    6 ай мурун

    Why if my car over heats when I’m yawing the ac

  • woocoheed


    6 ай мурун

    My blower motor resistor would go out all the time in my mkv rabbit

  • James K

    James K

    6 ай мурун

    Idk if its the camera but the R and the Miata yellow look the same shade

  • LMacNeill


    6 ай мурун

    Hey! My favorite Humble Mechanic! :-) I really like it when y'all do crossover videos like this.

    • Rusty Shackleford

      Rusty Shackleford

      5 ай мурун

      Sort of like back in the day when characters from one sitcom would show up on another.