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Car AC/Heater systems

Question - If the AC in the car is making you too cold and you turn the temp dial to "warmer" to make the air coming out less cold will that make the AC work harder and make your gas mileage worse? Why?

Reply to
>>>Ashton Crusher
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Ashton,

Question - If the AC in the car is making you too cold and you turn

No.

Dave M.

Reply to
David L. Martel

NO. it just moves a door to mix in some warmer air. Aside from that, the AC in cars today is very efficient and makes little difference to the mpg. Comfort is more important that a tiny difference in fuel cost.

Reply to
Ed Pawlowski

You already know the answer but just an FYI, driving with windows open will produce a bigger drag and decrease mileage than using the AC.

Reply to
Meanie

I've had my windows closed since 1967!!! Can't stand wind noise.

Reply to
>>>Ashton Crusher

Much of the time, I drive with the top down and the windows closed.

Much quieter with the windows closed, especially if cars are next to you.

Reply to
Micky

Same here. Love climate control, just never think about it any more. Maybe once or twice a year I'll open the windows for a short ride.

Reply to
Ed Pawlowski

All my smaller cars show acceleration decrease with compressor on.

An older car of mine, the temp slider controlled the thermostat off the evaporator. Never liked door mover systems. I'm going to assume, climate control also uses the thermostat method. The moving door technique should limit the air going through evaporator, thus limiting compressor usage.

Greg

Reply to
gregz

I'd say it depends. If it's summer and just the AC is running, setting it warmer will help with gas mileage, the compressor will run less.

If it's fall and the heat is on, then maybe it could result in a slight decrease in mpg. If the AC compressor switch is off, it will have no effect. But if the AC compressor switch is on, then the AC is running a bit to chill the air to remove moisture before it gets heated. So, having warmer air in the car, theoretically would mean that the AC compressor has to work more to cool the air down. But any effect is very slight and would be almost impossible to measure in mpg.

Reply to
trader_4

I don't understand climate control.

If i get in the car and it's cold, am I supposed to leave the temp set to, say, 70, and the heater will put out very hot air until it gets (close to???) 70 and the temperature of the air will (slowly???) decrease and be only warm when the sensor says 70?

It seems to me the air is never that hot unless I turn the temp up to

80, and that if I leave it on 70, it will take forever to warm up, but I'll admit I haven't kept tabs that closely.

I also don't like the Toyota climate control because it keeps changing whether i get outside air or not. You would think whatever setting it had when I turned the car off would be the setting when I turn it back on, but No. (I think it depends on the outside and inside temps, but knowing for sure would mean detailed records. )

Reply to
Micky

That's how all the ones in the cars I've had worked. When there is a big temp difference, the heater valve is full open and the blower is on a high speed. As it gets closer to the set temp, the heater valve is either cycled or partially closed and the blower speed decreases.

Reply to
trader_4

I've got one vehicle with automatic climate control and three without.

When driving the vehicles with just the 3 basic controls (fan speed, temperature and mode) there needs to be some tweaking done occasion as conditions change, such as sunshine, outside temperature, etc. I'm talking about during a given driving session, not day-to-day.

When driving the vehicle with the fully automatic climate control, there needs to be some tweaking done in occasion as conditions change, such as sunshine, outside temperature, etc. I'm talking about during a given driving session, not day-to-day.

In other words, there is no such thing as "set it and forget it" in any of the vehicles, automatic or manual. The automatic climate control is not like a house thermostat where it maintains fairly consistent conditions. There are too many variables associated with a moving vehicle for the climate control system (at least mine) to be a completely hands-off system.

I've got nothing against new technology, in fact I'm in favor of automating as much as my life as possible. However, in my vehicles, I prefer the 3 basic controls. If I'm forced to tweak things anyway, I'd prefer basic, simple to use controls.

Reply to
DerbyDad03

Hmmm. AFAIK, the automatic is on all the time, with no way to turn it off, and yet I don't think it's ever made the fan run faster (even though the fan speed control is electronic and it could). That's good actually, because I'd rather be cold a little longer than have to listen to a louder fan. (IIRC, the Lebarons had 4-speed fans and the first 3 speeds were quiet enough not to bother me. This Solara has a

5-speed fan, whoop-de-do, and only the first 2 speeds are quiet.)

But otherwise, your explanation is what I expected.

I guess this answers it. A friend with a Lincoln Town Car warned me not to get automatic, but I like high-end cars and most convertibles come with automatic AC, so I had no choice.

Me too. It also turns the AC on whenever I turn on the defrost, and I know that helps a bit but I still have to turn it off. The worst problem lately is the indoor/outdoor air setting.

I'll keep this in mind for the next cars but I'm not optimistic.

Thanks, both of you.

Reply to
Micky

Almost set in and forget. Even between driver and passenger seats depending on sun shine or shade they adjust the difference. What I like in auto climate control is, even if very cold outside as soon as I drive I can get warm air. Even prewarm the windshield to prevent fogging. For this I have to push one more button and leave it. Heat/Cool seat, steering wheel, sync'ing front and rear seat temp. settings, etc.

Reply to
Tony Hwang

There are virtually no "throttled" systems any more - and have not been for decades. The compressor turns off and on th controll pressures - and therefore heat transfer. Virtually all climate control systems use "air blend" technology Some systems used fixed orifice, some use an automatic orifice, and some use a temperature controlled expansion valve TXV) which senses the temperature of the evaporator and controls the amount of refrigerant allowed int the evaporator to prevent icing etc. There is also something called an "expansion block"system

The AC system controls the pressures and temperatures of the refrigerant for most efficient operation - the blens doors control the temperature of the air inside the vehicle. Newer compressor and control technology improve the efficiency.

Reply to
clare

Do. It should reach 70 in the same time regardless of what temperature (70 or above) you have it set for. There MAY be a small difference, but on my Ford I have never noticed it. My wife likes to fiddle with the settings because she THINKS it will warm up faster, and BELIEVES it does, so she FEELS it does. What really happens is it just gets warmer, so SHE warms up faster.

You get outside air ALL the time with a Toyota climate control system UNLESS you set it to MAX AC. The system will never restart in MAX AC mode by itself, nor should it. The system is most efficient in the normal mode.

Outside air is NORMAL AC. It is also NORMAL HEAT. Without outside air, particularly without the AC working, the humidity builds VERY quickly, the air gets stale, and the car starts to smell like a dead man's arm-pit. Not to mention the carpets stay wet, the windows fog up, and the car, generally, becomes unpleasant.

Reply to
clare

I have no need to adjust the HVAC (anywhere) as I have a wife, one daughter,

3 DIL and half dozen grand daughters. H*ll I have no need to make even one driving decision.
Reply to
NotMe

On the first really nice day of spring.

Cindy Hamilton

Reply to
Cindy Hamilton

That aside, I get better mileage in summer that with the crappy winter blend gas we get in New England.

Years ago, some compressors used to kick out if you floored the accelerator so you had enough power to pass. You could feel it cycle under normal driving even with a big V-8. Those days are long gone unless you have a really tiny engine.

In winter, I set the climate control to 70, in summer I set it to 72. I never feel the difference with the AC cycling, just enjoy the comfort. Really like the heated steering wheel on the very cold days.

Reply to
Ed Pawlowski

I beg to differ. My last two cars (2013, 2015) have been amazingly accurate. Once to temperature, they take care of any adjusting for sun load, humidity, whatever. I never touch the controls all winter or all summer when I keep it a few degrees warmer.

My present car I bought on Sept 28. I adjusted the control the next day and have not touched it since. My wife a couple of times has turned up the temp on her side, but I just set it back by touching the sync button when she it not with me. My last car was the same. I do recall a couple of older cars where I did twek a bit though.

Oh, it also turns the defroster on when needed too. Only once did I do that manually. It senses the windshield ready to fog.

Only thing I do when the car is still cold is turn on the heated seats and heated steering wheel, but after 10 minutes, I turn them off too. It kept the temperature just as good at 12 below too!

Reply to
Ed Pawlowski

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