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Old 01-24-2019, 12:16 AM
 
Location: Not far from Fairbanks, AK
16,302 posts, read 27,972,531 times
Reputation: 11942

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Quote:
Originally Posted by unit731 View Post
Here up North in hill and mountain country it can get quite cold.
Whether 32 degrees or minus 20 degrees.

Heating car question. Car is started and immediately on its way (moving).

One theory is to wait until car warms up to turn heater on. Car is moving.

Others state to turn heater on high immediately. Car is moving.

Turning on heater high immediately when minus 10 degrees only takes longer for heat to get to car as one is blowing frigid air through the heater core thereby taking longer for the heater core (coolant) to heat up.

Wait to car warms up some OR turn on heater on high immediately. Car is moving.

For this discussion - the car is not stationary and running to warm up.

In summary. People get in car when cold. Start car. Immediately drive to destination. Wait awhile to turn on heater or turn heater on immediately on high.

Which theory is correct?
When very cold and the car is parked outside, I just press the "start" button of the remote starter, and let the motor run for 18 minutes (the limit of the system I have in my car). If the temperature approaches -30 and colder, I let it run nearly twice as long before I get in my car. By then the cab is somewhat warm. When -20 degrees and colder and my car (or truck) has been parked a few hours, the tires develop a flat spot where it makes contact with the ground, so when I finally start driving I do so slowly for a mile of two, and then merge into the highway traffic and still drive under 55 MPH for a couple more miles to allow the tires to lose their flat spots and provide a smooth ride.

There is not way I am going to drive my car right away when the ambient temperature is below freezing, specially in the interior of Alaska where it gets real cold, and where even my breath freezes on the windshield and windows if there is not hot air warming the cab. And yes, the fan is blowing air at full blast when I start the motor from inside my home.

To another poster above: when you place the air flow control to "defrost," the car blends AC air with the air from outside being blown into the cab (cold and hot air are mixed). This is done to remove excess moisture from the windshield area. It does the same during the summer, rainy season, and so on. However, some automobiles disable the AC function at preset freezing temperatures.

Last edited by RayinAK; 01-24-2019 at 12:33 AM..
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Old 01-24-2019, 12:39 AM
 
Location: Not far from Fairbanks, AK
16,302 posts, read 27,972,531 times
Reputation: 11942
[quote=easy62;54234780]
Quote:
Originally Posted by victimofGM View Post
I work with hospital HVAC systems. If you don’t have auto climate control in your vehicle then put fan speed to low. This will give you a bit of fresh air without blasting freezing cold air into the vehicle. If your vehicle has a temperature gage then monitor it as the vehicle warms up. As you see it rise you can begin to slowly increase your fan speed. The faster you move the air, the less heat transfer happens. With lower temperature engine coolant you’re better to run the fan at slower speeds gradually increasing fan speed as it warms up. The only exception is if your windows are iced over. Some vehicles have a de-ice setting which turns off the compressor and directs the air directly onto the front and side windows. In this case turn the fan on full speed. While it warms up, work on removing excess ice from the windows. You want the temperature change to be slow and gradual to help prevent cracking.[/QUOTE



A modern car has a ventilation system that provides a constant through-flow of fresh air, heated if necessary. Modern cars are designed to have a constant through-flow of fresh air that keeps the interior atmosphere pleasant even with all the windows shut.
The only way the car has a constant air flow from outside in is if the controls are set to bring air from outside by the fan, or when the car is moving relatively fast. If the car is stopped and the blower is off, no air from outside is going to freely move into the cab. Also, if the control is set to "recirculate" the air, there is no outside air being blown into the cab.
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Old 01-24-2019, 03:11 AM
 
Location: Eugene, Oregon
7,881 posts, read 2,502,323 times
Reputation: 10987
Quote:
Originally Posted by mclasser View Post
The heater core acts like a 2nd radiator. In frigid temps, you want the engine to warm up as quickly as possible and not draw heat away from it. I agree with the user above about auto climate control. If you have it, just let it do its thing. It'll gradually start putting out heat as it deems fit, in relation to the engine warming up.

That being said - In my old car with manual HVAC, I don't turn on the heat until the car's been moving for a block or so. By then, the engine has some warmth and can put out some heat effectively.

I got stuck on the Hollywood Freeway once during rush hour, with 80 degree F. I was driving a car with a large, high-compression engine and it would overheat in that situation, at the 15 mph speed of the traffic. So I turned the heater on full and that made a big difference in reducing the overheating.
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Old 01-24-2019, 08:07 AM
 
Location: Metro Washington DC
12,742 posts, read 19,321,999 times
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I set the temp and fan the night before. I don't have an auto setting. However, the fan doesn't blow anything for a few minutes even though it is set to run. I guess my heater is a semi-automatic.
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Old 01-24-2019, 09:12 AM
 
3,095 posts, read 3,436,526 times
Reputation: 3865
Quote:
Originally Posted by unit731 View Post
Here up North in hill and mountain country it can get quite cold.
Whether 32 degrees or minus 20 degrees.

Heating car question. Car is started and immediately on its way (moving).

One theory is to wait until car warms up to turn heater on. Car is moving.

Others state to turn heater on high immediately. Car is moving.

Turning on heater high immediately when minus 10 degrees only takes longer for heat to get to car as one is blowing frigid air through the heater core thereby taking longer for the heater core (coolant) to heat up.

Wait to car warms up some OR turn on heater on high immediately. Car is moving.

For this discussion - the car is not stationary and running to warm up.

In summary. People get in car when cold. Start car. Immediately drive to destination. Wait awhile to turn on heater or turn heater on immediately on high.

Which theory is correct?
The heater core is usually located between the dash and firewall. There is no air flowing over it. You're thinking of the radiator.

Turning on the heater isn't going to affect anything. It'll blow warm air once the the coolant is warm, which usually takes five or ten minutes depending on the size of your engine.
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Old 01-24-2019, 10:22 AM
 
Location: Metro Detroit Michigan
3,353 posts, read 910,802 times
Reputation: 2731
Quote:
Originally Posted by st33lcas3 View Post
The heater core is usually located between the dash and firewall. There is no air flowing over it. You're thinking of the radiator.

Turning on the heater isn't going to affect anything. It'll blow warm air once the the coolant is warm, which usually takes five or ten minutes depending on the size of your engine.
Correct a heater core is hidden just look on passenger side of firewall and you will see 2 hoses attached to 2 nipples coming through the firewall that’s the heater core. The engine warms up the coolant and then the thermostat opens allowing collant to flow via the water pump it’s not rocket science. Just start car up idle for a minute then drive the heater will warm up faster because the engine is working harder and thus will warm up faster not because of airflow cumming through the radiator.
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Old 01-24-2019, 10:46 AM
 
Location: NYC
12,085 posts, read 8,063,261 times
Reputation: 13140
Fortunately I drive a Prius and I get heat a lot faster since it uses an electric heater before the engine warms up.
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Old 01-24-2019, 11:09 AM
 
9,216 posts, read 7,656,923 times
Reputation: 12294
Quote:
Originally Posted by Steve McDonald View Post
I got stuck on the Hollywood Freeway once during rush hour, with 80 degree F. I was driving a car with a large, high-compression engine and it would overheat in that situation, at the 15 mph speed of the traffic. So I turned the heater on full and that made a big difference in reducing the overheating.
My uncle was a mechanic for Dodge/Chrysler back in the 70s. He told me that trick. Came in handy one day in heavy slow moving traffic. Temperature light came on. Told my passengers we’re going to get hot, rolled down the windows, and cranked up the heater full blast. Literally saw the engine temperature come down enough to turn off the light and get a bit closer to the normal range until traffic started moving again.
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Old 01-24-2019, 11:10 AM
 
9,216 posts, read 7,656,923 times
Reputation: 12294
Quote:
Originally Posted by st33lcas3 View Post
The heater core is usually located between the dash and firewall. There is no air flowing over it. You're thinking of the radiator.

Turning on the heater isn't going to affect anything. It'll blow warm air once the the coolant is warm, which usually takes five or ten minutes depending on the size of your engine.
Umm, when you turn on the heater and the fan you are blowing air over it.
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Old 01-24-2019, 11:12 AM
 
9,216 posts, read 7,656,923 times
Reputation: 12294
[quote=RayinAK;54235125]
Quote:
Originally Posted by easy62 View Post

The only way the car has a constant air flow from outside in is if the controls are set to bring air from outside by the fan, or when the car is moving relatively fast. If the car is stopped and the blower is off, no air from outside is going to freely move into the cab. Also, if the control is set to "recirculate" the air, there is no outside air being blown into the cab.
Yep, that’s why windows can fog up in a “parked car”. All that moisture from our breath collecting moisture onto the windows. Just wish the cops wouldn’t come knocking when they saw those windows fogged up.
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