That depends on how convenient it is to pull over, how far you are from where you need to go, how far you are from where you can pull over and do something about it, what kind of traffic it is, how quickly the car is overheating, and how hot/humid it is, how much gas you have left, etc.
I have two gallon jugs of water in my trunk, because for a while a few years ago, my car would overheat at seemingly random times. There were times where I’d pull over and dump more water into it and sit and wait - there were times when I’d turn the heater all the way up and roll down the windows, it just depends.
Kinda a hijack but probably not worth another thread.
We don’t often have much problem with overheating up here in the north country but warming up the interior on a cold chilly morning can be a bracing experience.
Can any one explain to me why when it is twenty degrees below zero farenheit, the quickest way to warm up the cab is to turn on your air conditioner on high until the motor warms up enough to get any heat from the motor?
This is funny as heck. “Want the engine to cool down?
Turn on the heater! Want the engine to warm up? Turn on
the A/C!” And we wonder why some people are confused by their cars. ;]
There’s two ways to explain this. I’ll try the conceptual/intuitive explanation first, and then the literal one.
Conceptually, you understand that by turning up the heat, you’re drawing heat out of the engine and blowing it into the interior of the car, right? And naturally, since you’re taking heat out of the engine, the engine gets cooler. So, think about the A/C. Conceptually, it’s taking <b>cold</b> out of the engine, and putting it into the passenger compartment. Thus the engine gets hotter. Simple, right?
Of course, it doesn’t really work that way. Under the
hood there’s what’s called an “A/C compressor.” It’s a lot like the compressor that powers your fridge, in theory. It’s attached to the engine with a belt. The engine spins the A/C compressor, and the AC compressor “makes cold.”
Normally, when the A/C is off, the compressor detaches itself from the engine (with a magnetic clutch, usually) so it doesn’t cause any drag on the engine. But when you turn on the A/C, the clutch hooks the compressor and the engine together. At that point, some of the engine power that would normally make the car go is used to spin the compressor to make cold. Now the engine is working harder. And when it
works harder, it gets hotter faster.
And that’s why turning on the A/C makes your car warm up faster. Isn’t it ironic? Don’t you think? ;]
-Ben
I follow what you are saying ModernRonin2, but in my experience, turning on the air conditioner brings immediate heat, apparantly not engine heat as the engine is still cold.
The air conditioner also provides the moisture-removing properties of your defroster. When the defroster is on, you’re mixing the cool, dry air produced by the AC with the warm air from the heater core, making warm, dry air.
In Minnesota in winter, maybe the AC output air, cold as it is, is still warmer than the outside air? That would make it be effectively a defroster even if the defroster itself wasn’t on.
If making the engine work harder made it warm up faster (which is largely true), the most effective way to do it would be to simply get the car moving. The engine has to work much harder to do that than to run the compressor.
My dad and I were traveling across country in July 1996 in a car that really should have done that. One of those “owned by little old lady who only drove it once a week for 20 years, but never changed an ounce of fluid” type jobs. It was a 74 or 73 something. Anyway roundabouts Nashville and their rush hour the little temp gauge went deep into red so we turned on the heater full blast … in the July midday sun of the south and the temp came down to about a little over midway. And that’s how it stayed for the next 9 days as we drove through GA, FL, MS, AL, LA, AR, TX, OK and KS. And we had to keep it on, even after my dad tore the engine apart in an outlet stores parking lot outside of Brunswick, GA and replaced a broken water pump, and some really gunked up gaskets. And despite the two flat tires (one that nearly killed us), busted water pump and a popped hose and the 3 extra days on the road caused by such mishaps we made it home, with 26 cents to spare (out of $1500) although that was only after 30 hours straight on the road so I could make my flight back home. But hey, it builds character
I think he got rid of the car as soon as he got back.
The list just a bit above this post hit on just about all the other comments I was thinking about.
1 other thing. The defrost often turns on the A/C as mentioned in another post; if the car has an electric fan on the radiator, turning on the A/C should turn on the electric fan. If a bad tempeture switch is a cause of a fan failing to cool the engine, turning on the A/C may actually help - AND it will work regardless of the hot/cold setting.
Running the heater will cool the car down as many have indicated. It works in a pinch but I would echo that advice that if your cooling system fails you had better get things fixed as soon as possible.
My car has an automatic temperature control so running the heater on high for any period of time isn’t possible unless it’s fairly cold out. The thermostat in my car will shut the heater off when the interior reaches a preset temperature with a maximum setting of 90F. My heater won’t even fire up on a hot summer day unless I’ve been running the AC first which does warm up the engine.
After your tires, your cooling system is the #1 cause for breakdowns. It’s a good idea to make sure that it is operating at peak efficiency and that your belts and hoses are in good shape.
I have an electric fan and one of the things about it that bugged me was the fact it didn’t cut in soon enough for me. I wired in a switch so that I can manually turn the fan on/off. It’s a great feature if you have to wait in traffic on a hot summer day.
My cooling system is in great condition, I just did a complete servicing by flushing the system and replacing the coolant (good to -50C). I also installed a new safety thermostat which is designed to remain open in the event of failure. When a normal thermostat fails it will stick in the closed position and the car will overheat as no coolant will be flowing into and through the radiator. The new thermostat was the same price as a regular thermostat. Keeping my car running cool is important because I also run a turbocharger which adds more even heat to the system.
I replaced the top rad hose and changed my belts as well. I keep the old parts in my trunk in case of an emergency as although pantyhose might be good, carrying a spare belt and some hose is better. I also have two gallons of premixed antifreeze/water in the trunk.
'85 Tercel owner checking in. We’ve had some bad radiator problems with this car (the fault of the previous owner, who flushed the radiator and replaced it with PURE WATER instead of a mix of radiator and coolant, thus causing the radiator to totally rust out… but I digress). Anyway, when I’m in traffic and I notice the temperature gauge inching up, I’ll go ahead and turn the heater on full blast, and usually the indicator will slide back down below the halfway point. However, I only do this if the temperature is just slightly above halfway. If it starts spiking higher, or goes into the red, I immediately pull the car over and kill the engine. I’ve learned from sad experience that once the temperature is in the red zone, you DO NOT want to run your car anymore, whether the heater is running or not. It’s a quick fix if the car is threatening to overheat; if the car already has overheated, just turn the thing off.
(FYI, usually I could get the car home simply by pouring water into the radiator from a 2-liter bottle we kept in the car for this purpose. What would happen is that the radiator fluid would slowly leak out through the rusty cracks, so eventually we’d have none. This went on for about two months and then we finally bit the bullet and replaced the damn radiator… and this has been More Than You Wanted To Know About MsWhatsit’s Car.)
Next time you drive in the wintertime put cardboard directly in front of the radiator, actually on the radiator. Experiment with various sizes. The best way is to have a sheet covering the whole radiator with a cutout in the middle to allow airflow. I was told to do it this way to keep the fan blades from flexing as they pass from blocked areas to open areas. The theory was that this flexing could lead to failure of the blade. Probably not true, but that was the theory.
Practically, I would just carry some pieces of various sizes and just slide them in and out until I got it just right. You can be warm as toast with this system, but you’ll have to keep an eye on the temperature guage, but I guess you’re used to that.
Another factor to consider- Coolant (sometimes referred to as “antifreeze”) of the ethylene glycol type must be mixed at a 50/50 ratio with water in order to effectively protect against freezing and boil over.
Pure glycol, that is, no water added, freezes at a much higher temperature than the 50/50 glycol/water mixture. Pure water boils at a much lower temperature than a 50/50 glycol/water mixture. The pressurization of the radiator system prevents overheating/boilovers as well- slight leaks will cause overheating, boil over. Slipping fan belts as well.
I think it was Gumball Rally (which IIRC preceded Cannonball Run) where the two guys are driving across the Midwest desert in a big muscle car at 120mph and the one is complaining about the heater, the other says they have to do that to stop the engine from overheating at high speed.
A good example of using the heater effectively might be when pulling a hill with a load, your temp is creeping up slowly as the radiator fan cannot quite keep up, turning on the heater would often make the difference in the cooling system being able to keep up.
It was working fine until I had a plow put on it. On my way home after the plow install it started to overheat because the plow blocked clean airflow over the radiator. I turned on the heat high blast (not fun in the small cab) and it certainly worked helping to cool the engine.
Turns out the clutch on the radiator fan was not kicking in (got that diagnosed right here on the SDMB).
I had to do this when driving my husband’s 93 Honda Del Sol a while back. I noticed the car would tend to overheat when I was stuck in traffic but be fine when driving at freeway speeds. So there I was one day, stuck in L.A. freeway traffic, there was an accident at an interchange so we were crawling along, nowhere to pull over, middle of summer, with the heater blasting to keep the car from going critical. I got the car to a mechanic shortly thereafter and got the thermostat replaced.
So yes, it can work in older cars, but it’s a temporary measure at best. And a pretty miserable one in the middle of summer!