Minimizing A/C use

[evilskillit]

Simple answer, the AC may have continued to run after you thought you turned it off. In my 2003 Sentra the AC seemed to have a minimum amount of time that it would run, I'm not sure if this was to keep condensation from building up in the vents or what but if you pushed the button to turn it on then pushed it again to turn it off the light would go off but the compressor would keep running for quite a while. I eventually figured out a hack to disable this so you can turn the ac on and off as you please. Its entirely possible this malibu was exhibiting some similar behavior and you couldn't detect it since it was an unfamiliar vehicle.

[p38fln]

my 2011 F-150 does some crazy weird stuff with the AC as well - I've got the base system with the red and blue knob and another one labeled 1234 for the fan speed.
Sometimes, even without the AC on, and the system set to 'vent' (not blend or defrost), the air coming from the vents will be ice cold.
From what i've heard this is Ford's way of ensuring that the AC compressor will always run sometimes to prevent issues caused by long periods of not being used. It shuts back off within a few minutes of the engine being started.

It also appears to adjust how 'hard' the compressor runs based off the outside air temperature - the air coming from the vents at 95 degrees ambient air temp is noticeably cooler than the air coming out at 75 degrees.

[Hatchtastic]

As an automotive technician I will also confirm that your AC stayed on for that trip. Many new cars keep the AC on to de-humidify the incoming air, and with re-circulate selected.

AC systems cycle on and off by themselves based on cooling load (demand). You really shouldn't have to be switching your AC button on and off, just turn the fan down. If you have a low fan setting, it will not be taking much chill off the evaporator core, and the AC clutch will shut off from lack of cooling demand. AC systems have pressure switches to control their on and off times. If you don't demand much cooling, the pressure differential from the high side to the low side will cause the compressor clutch to turn off. On a cold day, your AC won't cycle on as much compared to a hot day, due to less cooling demand. At least that's how it works in my mind . I'm not sure if you could also reduce cooling load by turning the temperature blend a bit warmer if the lowest fan setting is still too cold. It makes sense that it would, because you are drawing even less air across the evaporator (depending on system design). This would all be interesting to test for someone with a ScanGauge. Do some A-B-A-B testing with manually cycling AC (pulse-and-gliding AC?) vs. using a very low cooling demand setting (low fan and/or warmer blend).

[MaxHedrm]

Originally Posted by roosterk0031

I have 03 Malibu, 95 degrees out today, ac on/recirc on for first 15 miles temp OK. Turn ac off, recirc on, no change in temperature inside car for 15 minutes, turn recirc off, humidity & temp rises in minutes. I think the recirute button overrides the ac switch, it was without adoubt running, no change switching ac button on or off, all highway so I couldn't feel it cycling but I know it was. I'll try with the 10 Impala I bet it works the same.

Yeah, that makes sense, otherwise you would end up with too much humidity in the car over time, which is definitely a bad thing.

Originally Posted by Neddy Seagoon

When driving my car I just use the Defrost setting it cools the car just nicely for me with out freezing me

Not very humid where you live? I think in some areas if you did this you'd get condensation on the outside of your windshield.

[p38fln]

i can get away with the defrost setting for AC if its for a short time - longer trips (Anything over 30 minutes) and condensation will form. I have to be sure none of the vents are pointed at the windows as well.

[henshao]

Someone said it earlier and I'll said it again.

You wouldn't believe how much window tint can change the game when it comes to maintaining a cool cabin. My first car was a police interceptor with borderline limo tint still on it...

once you got that initial heat out of the car you had to turn the a/c down to the lowest fan setting and close two vents to not freeze. Closing vents is something I do anyway because it increases the pressure in the vents that are open, no point in cooling a phantom passenger. Try closing all the vents but one in your car sometime and see how much air comes out that one vent even on the lowest setting.

[Thymeclock]

Originally Posted by p38fln

i can get away with the defrost setting for AC if its for a short time - longer trips (Anything over 30 minutes) and condensation will form. I have to be sure none of the vents are pointed at the windows as well.

That's because it's cold(er) and dry(er) inside the car than the atmosphere is outside, so you would need to use your wipers to clear the condensation that forms on the outside of the windows. The way to avoid this is to turn the A/C down from the coldest setting so it isn't quite so cold. If you wear eyeglasses, and if you have the vents aimed at you, your glasses will also fog as soon as you leave the car. It does pay to leave the system on recirculate however, as reducing the humidity in the cabin is more comfortable if the weather is very humid.

[RandomFact314]

Haha this is funny because I just got out of a car we rented for a long trip and it was a 2012 Malabu with 40 miles on it (before we drove it) and the whole week I drove it I freaking LOVED the A/C in it, that auto function was awesome

[jdub]

On my 2010 Jetta TDI, I have noticed that toggling the air on or off an inperceptable difference in FE. I can get 54 mpg on my route to work with the air on which is basically the same as running with it off. I attribute this to the torque of the diesel motor. My Jetta is white (with black interior) but toggling the AC button only allows the air to remain cool for perhaps 1-2 minutes at a time which sounds similar to what you are experiencing in your 08 Jetta. I live in Texas and we are currently experiencing daytime highs of 100+ and morning lows in the mid 80s. The real key to this is what is the FE effect of driving the Malibu with and without the AC and is that difference enough to justify it as a primary deciding factor in changing cars? (You didn't mention if your Jetta was 2.0T or TDI and if it is diesel its definitly not worth trading it in for a Malibu!).

[SwamiSalami]

Originally Posted by jdub

You didn't mention if your Jetta was 2.0T or TDI

It's the sporty one. The 2.5l.