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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?

  • 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 – Zach Saucier Dec 10 '14 at 4:38
  • I kind of doubt there are many hackish ways to answer this question – Zach Saucier Dec 10 '14 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 '14 at 19:41
  • 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 '16 at 23:34
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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.

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    +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 '14 at 21:54
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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.

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    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 '14 at 21:52
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    +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 '14 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 '14 at 21:46
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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 '14 at 6:08
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    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 '14 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 '16 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 '16 at 19:54
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-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

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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.

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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.

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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.

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