In the winter, after turning on the ignition, it takes approximately 15 minutes for the vents in my car to begin blowing hot air. Before that time, the vents blow cold air even if the "heat" setting is turned on. Sometimes, it is okay if I wait 15 minutes, but if I'm in a hurry, this method doesn't work.

What can I do to cut this time down? For example, would it cut the time down if I did not turn on the heat until after a certain period of time? Does it matter if I drive or if the car is idle as it warms up?

  • 2
    Learning how a car heater works would answer most of your question. The car needs to be running because the air heater is (usually) based on heated water from the engine Dec 10, 2014 at 4:38
  • I kind of doubt there are many hackish ways to answer this question Dec 10, 2014 at 4:42
  • @J.Musser: I added my attempted method. Unfortunately, since I don't know much about cars, I don't know many methods to attempt. That is why I asked it here.
    – JSW189
    Dec 20, 2014 at 19:41
  • 1
    One thing that you can do is have a spouse who complains and doesn't understand why the heat is not coming out straightaway. You can warm yourself up by explaining how the heat system on a car works, and their body heat and outrage will mitigate the cabin temperature. This usually works about thirty times, because they do not listen to the explanation, so you can count on it being effective for a while.
    – user13683
    Apr 28, 2016 at 23:34

14 Answers 14


I do not think keeping the heat off until the engine got warmer would help. I would suggest a plug in engine warmer, they are cheap and easy to install. They cut the warm up time for your engine by half or better and also help preserve your engine in really cold climates. Parking in the sun if you can also helps.

A very late addendum:

Start driving! It will get your car warmer quicker then anything. Modern fuel injected gas vehicles do not need long warm up times to run properly and safely with the proper oil and anti-freeze. Anything longer then getting oil pressure is wasting fuel. Warming up your engine at an idle is simply a waste of fuel and causes a lot more wear on your engine then driving away.

In extreme cold like sub zero temps one should be using engine heaters to avoid frozen radiators and oil turning to a grease like gunk. If you have the engine heater you do not need to warm a modern fuel injected engine beyond a very short time in extreme cold. Also extreme cold is very dangerous to drive in and unless you really need to, don't.

Diesel engines are a little different. Diesel combusts poorly when the engine is cold. In a cold diesel the performance can be so bad that driving could be unsafe, and fuel is wasted.

  • 2
    +1 for parking in the sun. I try to park with my car facing the morning sun, as the windshield lets the maximum amount of sun into the interior. In borderline cases, it also saves scraping frost from the front window.
    – TomG
    Dec 21, 2014 at 21:54
  • I hope you mean a combustion-based "engine warmer"? If yes, then I give you a vote :) If it is electric, it shortens the life of the battery.
    – virolino
    Oct 10, 2019 at 5:20
  • 2
    Electric engine heaters are mains-powered.
    – Hobbes
    Oct 11, 2019 at 14:31
  • Parking in the sun might not always be a possibility, when at night, try to park under a lightpost. Also saves scraping time! Oct 15, 2019 at 7:34
  • 1
    @virolino A plug in engine warmer plugs into a wall plug, at the house where you park. They are typically a small heater element that wrap around the lower radiator hose or plug into your engine block in some manner. very cheap <$100. Bigger engines like diesels need something more and that's were one might consider expensive combustion heaters.
    – Jon
    May 18, 2020 at 18:08

-30 this morning in Fairbanks Alaska. If you really want to know how to warm and maintain a vehicle during a truely cold winter (not the stuff a lower 48er considers cold) you need to ask an Alaskan or Canadian. Here is a list for you to do a search on:

  • block heater
  • oil pan heater
  • battery; blanket, pan heater or trickle charger
  • transmission heater
  • radiator thermostat (winter)
  • grill cover
  • seat warmer (these are nice)
  • low viscosity oil (winter weight)
  • winter coolant
  • high idle switch or idle adjust
  • auto start

... or if you want to save money just build a heated garage


Your heater will reach useful temperature faster if your engine heats up faster, as it takes its heat directly from the engine (usually by water heated by the engine block) - and the engine block heats up faster under load, so:

  • turn on front and rear windscreen heaters
  • turn on lights
  • rev the engine one it has reached operating temperature (ideally accelerate hard using wide open throttle)
  • use your air con
  • even turn your stereo up (although this probably only has an effect if you have a powerful amp)

While the engine is warming up, select recirculate if your airflow has that option. This means you are just heating the air in the car, not having to heat cold air coming in.

Keep the air con fans on low until you start to feel warm air, then select incoming air.

  • 6
    Keep in mind that you should not rev a cold engine excessively until it begins to warm up. Except in extreme cold, 1-2 minutes should be OK.
    – TomG
    Dec 21, 2014 at 21:52
  • 1
    +1 to TomG. While this is effective, I would consider it dangerous advise at best due to undue wear and tear on your engine from running it hard before it hits operating temps.
    – Sidney
    Dec 22, 2014 at 21:45
  • At no point did i say Rev it before it got to temp. Hang on, I'll update to make it clearer
    – Rory Alsop
    Dec 22, 2014 at 21:46
  • @RoryAlsop when it is at operating temperature,the thermostat will open allowing warm water to circulate and warm the cabin. Not sure that step will do any good. Oct 8, 2019 at 17:56
  • @jamesjenkins Perhaps we think of the thermostat as different things but your comment may be inaccurate; When the engine is cold the t-stat prevents the coolant from circulating through the radiator that cools the engine, but not the heater matrix that heats the cabin. When the engine reaches operating temperature the t-stat begins to open to allow hot coolant through the rad, whereupon it cools down and can be used to modulate the engine temperature. Cars with climate control might not activate the blower(in auto)until the heater matrix is warm enough but this isn't directly a t-stat function
    – Caius Jard
    Oct 8, 2019 at 21:18

As a mechanic this is what I like to do:

Let's say I didn't plug in the vehicle and it's parked outside. If I absolutely had no choice but to sit in the car and wait for it to warm up such as when I go to a restaurant with friends for a few hours and then leave during a cold snap.

  1. Interior heat is set to full cold and fan off. This will help the coolant get to temperature quicker for both the coolant and the engine. If you have heated seats and/or steering this is the best time to turn them on.

  2. After about 1-2 minutes of starting the engine and the pistons have expanded to help prevent piston slap I would raise the RPM to about 2,000 - 3,000 in neutral or park. This will help warm up quicker but there isn't any load on the engine. I do this to reduce internal wear and damage to the engine as opposed to driving right away.

  3. Once the coolant gauge needle reaches the first line or blue coolant light disappears from the cluster I would turn the heat to full high and fan on low to medium (still cold air from the vents but but this will start the circulation tot he heater core which gives your interior heat. At this point less than 5 minutes should have elapsed but the colder the outside temperature the longer this will take.

  4. Start driving but avoid hard acceleration. Again this is to help prevent the engine from internal wear/damage due to the internals haven't yet reached their operating temperature. Don't mistake this for the gauge for even if the gauge reads operating temperature the actual engine coolant may only be at about 50C while the engine's normal operating temperature is around 100C. At this time I would set the heat in full high and fan speed at high. The heat from the vents are this point on should be sufficient in warming up the interior in no time.


I consider all possible answers to this question non-hackish.

Yet, here is what I do:

  • I usually park my car in an area where the sky is not exposed. This means if it's freezing, the windshield does not usually have a layer of frost. If a car is parked under exposed sky, the windshield will radiate its heat to the space, meaning it becomes so cold the humidity in air deposits over the windshield. Thus, with no ice on the windshield, I can drive away nearly immediately.
  • If it's very cold, I use an engine block heater and car interior heater. They use electrical power so they can be realistically only used if an electrical outlet is nearby.
  • If the windshield nevertheless has a layer of frost, I activate my electrical windshield heater. Not all cars have this but it's a very useful optional accessory. Unfortunately you can't install it later as the wires are inside the windshield. If it's very cold it might take some time to remove the frost from the windshield. Then I let the car idle, knowing well that the windshield heater uses some non-trivial amount of electrical power, meaning the engine alternator has a non-trivial load and thus helps in putting a gentle load on the engine, thus making the engine warm up faster.
  • I drive away immediately, driving the car with light throttle. The purpose here is that there are two things a cold engine doesn't like. One of them is heavy load with throttle on the floor. The other of them is excessive idling with no load at all so heating up takes practically forever.
  • I have an automatic climate control which uses the fan on the lowest setting until the coolant becomes hot and only then activates the fan. If you don't have an automatic climate control, you should do the same manually: fan on minimum until the coolant becomes warm and then fan at maximum and heat at maximum.

Additionally, my car is a hybrid (non-plug-in hybrid). I presume the hybrid car computer knows how to distribute the load between the engine and battery. Presumably when driving away nearly immediately, nearly all of the power comes from the battery and then when the engine gradually warms, its share of load increases. When the engine is so warm it can take significant load and when driving at low engine load, then the partially depleted battery starts to be quickly charged so it provides beneficial load to the engine and helps with fully warming it up.

Also I don't use the eco mode of my car. In the eco mode, the positive temperature coefficient (PTC) electrical heater is disabled. In normal driving mode, it is enabled. It provides heat to the interior electrically (albeit very slowly) and at the same time provides helpful load to the engine, thus reducing the engine warmup time.

The worst thing you can do is to let the car warm up idling and at the same time remove the frost mechanically from the windshield by a scraper. If you expect that frost can form on the windshield and you may need to remove it mechanically, use the windshield washer to squirt some washer fluid on the windshield and activate the wipers immediately before parking. This eliminates the small sand particles from the windshield, thus when you scrape it the sand particles won't scratch your windshield (a car that has the windshield scraped often without the washer fluid trick will very soon have a windshield full of scratches). Then when you need to mechanically remove the frost with a scraper, do it with the engine off. The few minutes the engine spends idling won't make the warmup noticeably faster because an idling engine doesn't have load and thus warms up very slowly, and will cause excess engine wear.

Also consider the start of your trip. It should be appropriate for the engine warmup schedule. Five year ago I lived in an area where one of the directions had a very steep hill immediately at the start of the route. It would be very beneficial in this case to avoid driving up that steep hill with a cold engine. Today, I live in an area where my usual route has a quick acceleration to 60 km/h road nearly immediately after startup. I no longer take a different route because my current car is hybrid and I understand that most of the engine power comes from the battery initially, thus the quick acceleration won't kill the engine in this hybrid car. However, for a regular car it would be extremely beneficial to take a different route and avoid that quick acceleration at the very start of the journey.


Use a piece of cardboard or Coroplast to block airflow through the radiator. Do a search on "grille block" for details.

@darthness: The only real hazard I can think of is that you forget to take it out in the summer (or if you have to climb mountains), and the engine overheats. But that's why we have temperature gauges, and aftermarket OBDII scanners :-) I don't have pictures, and details are going to vary depending on your particular car.

@yankeekilo: To a certain extent that might be true, depending on whether or not you have a thermostatically-controlled fan or not. But I'm assuming educated drivers, who know enough not to waste gas by leaving their engine idling for long periods.

  • Wow! This method is really interesting :) If you added any hazards, some more details and maybe a picture I would more than to upvote for ingenuity.
    – Pobrecita
    Dec 27, 2014 at 6:08
  • 2
    This will most likely not be effective until the car moves and you get significant airflow. The ventilator too will only start working in earnest once a sufficient water temperature is reached, but not right away.
    – yankeekilo
    Dec 27, 2014 at 17:03
  • Often you can feel the moment when the thermostat opens and allows coolant that has been circulating around the engine block to go out to the heater core for the passenger compartment, and the radiator. Sometimes the radiator is wet and you can see a bit of water vapor coming off of it. Until that moment, no joy. If your thermostat is stuck open, ironically, the engine will reach operating temp slower, and it is bad for the car. If it is stuck closed, it will not give you any heat and will overheat and you will have to stop, get out in the cold and walk.
    – user13683
    Apr 28, 2016 at 23:32
  • This is not going to warm the car up faster. If the car is too cool on the freeway then use this.
    – paparazzo
    Nov 29, 2016 at 19:54
  • Unlikely to work unless your car's thermostat is faulty in which case you should replace the thermostat
    – Caius Jard
    Oct 8, 2019 at 20:21

First thing, park in the sun.

Beyond this, we're assuming a gasoline or diesel engine, not a hybrid or electric vehicle (most of those have electric heaters and will start blowing hot pretty quickly anyway).

If, like me, you leave home for work before the winter sun is up, or must park under cover but without heated space, your engine will warm faster with the heater off (it acts like a radiator, but without benefit of a thermostat to control coolant flow through its core), and under load. Don't turn on the air conditioning, but do turn on lights and (electric) rear defogger if available. Don't run the heater fan, and set the temperature control to cold (you want to close off coolant flow through the heater core).

Now, move off as soon as the oil pressure is normal (warning light out or gauge in range). Watch the engine temperature gauge, and turn on the heat or front defogger (as you choose or need) as soon as the temperature is off the peg, or at least two minutes after startup if you don't have a gauge.

These steps will give you the fastest engine warm up, hence soonest useful heat, and avoid wasting fuel at idle (when you're getting zero miles per gallon), as well as limiting engine wear (a cold engine doesn't wear faster under load than at idle, but warms faster under load). In that light, if you have to deice the windshield and windows before departure, scrape before starting the engine. The exercise can warm you, a little, and if you're properly dressed the weather won't chill you or your hands.

Once you're on your way, drive with appropriate caution; watch out for ice, especially on bridges and overpasses.


Revving the engine will make it warm up faster but it is not a good idea to rev a cold engine. The metal parts are contracted so extra gaps. The oil is not warmed up. You should let it just idle for at least a couple minutes. The oil will warm up pretty fast. You should see the oil pressure come down a little bit when the oil warms up. I wait for the idle speed to come down.

When it is cold the engine will just circulate water in the block. The block is massive so there is a lot of heat capacitance. The transmission will also pull off heat.

I wait to see the temperature gauge move and then turn on the heat / defroster.

Or you can just turn on the heater / defroster first thing. Yes it will take longer for the engine to warm up but you will also get some heat in your vehicle.

Don't rev the engine or accelerate hard until it is up to normal operating temperature.

Turn on lights and electrical heater(s) is good for a light load.

If you are in a hurry I suggest a heavy coat, hat, and gloves. If you let it idle a full 15 minutes to heat up that is a bit of fuel. If you are willing to drive easy the vehicle is ready to go after a couple minutes. If you only need to drive a few miles then just gut it out.

Window fogging up and deicing is another thing. Recirculate to hold in heat but you will need to to bring in external air if the windows fog.

My hack is wear more clothes.

  • Side note one of the functions of the air con is to dry the air; if you're running in recirc and have air con you can activate it to defog/demist the windows quicker and prevent fogging by keeping the air dry
    – Caius Jard
    Oct 8, 2019 at 21:20

Seems something is wrong with your car. 15 min is too long period i guess. Check if your thermostat got stuck in "long circuit" position, when the main radiator become a part of water circuit.. Because when the engine is cold, the thermostat must be in "short circuit" position and the main radiator is disconnected from the cooling circuit for more fast engine heating.

  • 3
    15 mins is reasonable in a cold climate. One doesn't need to wait for the temp gauge to reach operating temperature before warm air will be experienced but 15 mins of light driving in a very cold climate isn't unreasonable
    – Caius Jard
    Oct 8, 2019 at 20:31

My life hack for this is to run an extension lead out to the car with a fan heater and one of those mechanical timers (with the little plastic tags you press in to activate 15 minute intervals).

Half an hour of dedicated heat in a morning before the commute lasts long enough for the cabin heat to take over when the engine has warmed, and having the glass be warm will aid defrosting the outside, will demist/defog the inside and help prevent re-icing/re-fogging of the glass.

It's most helpful if you then don't run the blower as this will import cold air from the outside, unless you have the recirculate control on (which can prevent cold fresh air entering at higher car speeds and help maintain cabin warmth, though remember to switch recirc back to fresh to prevent accumulating moisture making misting/fogging worse tomorrow)

In terms of warming the engine, just drive it. Don't idle the engine - not only is it illegal in some jurisdictions it can put you at risk of having your car stolen, it costs more money than using a fan heater and it is not an environmentally friendly course of action. Having the fan heater timed means your car is warning while you're busy doing other things. Aim to purchase a fan heater that deactivates if it is tipped over or if the exit blower stream is blocked (overheating protection)

As noted, avoid running the blower; blasting cold air in your own face won't make it appreciably longer before the engine has warmed the coolant enough to provide some cabin heat, but it will certainly make it feel that way. Humans experience flowing air as cooler than still air for a couple of physical reasons (look up "windchill")

Keep your air con on; it will decide itself when it needs to deactivate (most systems turn off if the incoming air is too cold and the climate control wont succeed in reducing its latent humidity) and for the most part it keeps the air more dry inside the car. A car with a damp interior warms more slowly because heat energy is used in evaporating moisture from surfaces

Covering the cabin glass with a blanket can helpful to this "preheating with external heat source", as well as helping prevent icing of the glass

Other options to consider, though none of them are really lifehacky unless youre making them yourself as they all rely on a bought solution of a product intended for the purpose:

  • cigarette lighter powered fan heaters exist - no comment on the effectiveness of them though; I can't imagine you'll plug it in and feel like you're sat in front of a roaring log fire
  • fit one of the systems that routinely cold countries use to help vehicle users cope with the cold - engine pre heaters, cabin preheat etc. Basically a more intense, dedicated version of the fan heater hack
  • fit aftermarket heated seat covers, or replace the seats for ones that have heating built in, if your car has the wiring for it (or rig up a control/switch if it doesn't)
  • some cars have electric duct heaters that provide air heat in the absence of coolant heat or vacuum flasks that retain hot coolant from the previous engine run, and it may be possible (though unlikely to be economically viable) to retrofit these
  • 1
    cigarette lighter powered fan heaters exist - I tried one, and I can't recommend it. They're limited to ~150W, which is far too little to heat up the interior noticeably. You can't even defrost the windshield with one. Wasted money, all of them.
    – Hobbes
    Oct 11, 2019 at 14:33
  • Electric duct heaters are a better option, they're far more powerful (VW has one for the Golf, rated at 60A, about 800W).
    – Hobbes
    Oct 11, 2019 at 14:37

Frameshift: Don't wait for the car to warm up. Warm yourself directly:

Source: https://www.amazon.com/Naipo-Ventilation-Function-Breathable-All-Season/dp/B07SYKJM6V/ref=sr_1_10?keywords=car+seat+warmer

A car seat warmer will pull energy directly from the electrical system to start heating within 60 seconds rather than waiting for the entire mass of the engine to heat up before you start feeling warm air.

This shouldn't have much impact on the battery or electrical system as the seat only uses 45 watts of energy compared to the car's engine which requires as much as 4800-12000 watts for ignition. (400-1000 Amps x 12v)

  • 1
    This solution will have a huge dramatic impact on the battery. When it's cold, the battery suffers a lot of stress, the electrolytes are not doing their job properly and so on. The additional stress of the electric heater will guarantee the untimely death of the said battery.
    – virolino
    Oct 10, 2019 at 5:18
  • 1
    Assuming the car is running, it does not really take power from the "battery" it takes power from the electrical system, in most cases the alternator. It is no different then turning on the lights. P.S. same as the lights, don't leave on with the car not running. Oct 10, 2019 at 14:53
  • 1
    @virolino The seat draws less than 50 watts at full power. Compare that to starting the car at up to around 5000 watts (200-1000A * 12v) in the cold and it's insignificant in comparison. Oct 10, 2019 at 15:44

I always hear that we only have to warm the vehicle for a couple of minutes and anything after that is just wasted fuel. While this may be true for most of the US and lots of Canada as well, it's not true at all if you live in Alaska or the Yukon. Even if the engine is at running temp, it's not safe to drive if the moisture from your breath ices up the inside of your windshield or when the heater nob snaps off when you attempt to turn the heat on.

If you live in areas where there is extreme cold, use a command start and have the heater already set on high. While this may prolong the warning process a bit (for reasons already stated), it will save interior plastic dials or even the inside door handle from breaking off when you turn dials or shut your door (I had an interior door handle snap off when I slammed the door shut at -45. So having the interior warmed up before you get in the vehicle will save the interior from becoming too brittle in the cold. Use a block heater with a timer and set it to begin warming your engine coolant for minimum 2.5 hours to a max of 4 hours in the morning before you get up. Anything more than 4 hours is paying for wasted electricity. Have your heated seats set on high as well. In extreme cold, 15 mins until warm air blows is actually pretty normal.

Now if I could find a way to stop my power steering fluid from gelling up and causing my steering wheel to stiffen up (I bet most of you have never even experienced that)...


Try a diesel hot air heater, some run on gas, much easier, it's down the idea truckers use to keep the cabin warm at truck stops.

  • 1
    This would work, but where I come from, a diesel vehicle heater costs around £1,000, so not cheap.
    – Chenmunka
    Nov 1, 2021 at 16:46

Ensure the radiator fluid is not worn out. Freshen it up, flush and replace anti-freeze to see if that fixes it.

  • 2
    This answer is so wrong... Oct 8, 2019 at 17:52
  • 1
    "Not even wrong" :-(
    – jamesqf
    Oct 9, 2019 at 16:13

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