Minimizing A/C use - Fuel Economy, Hypermiling, EcoModding News and Forum

SwamiSalami · 07-15-2011, 10:53 PM

I have had a rental car for the last two days. 2010 Chevy Malibu.

At first, I hated the idea of driving this car. Compared to our 2008 Jetta, I just knew that this car was going to be crap.

However, I am now eating my words.

I am almost completely sold on this car for the simple fact that the A/C system is incredible.

As an efficiency guru, I do my best to minimize A/C usage whenever possible. I do this by recirculating the air in the cabin and toggling the cooling function.

Unfortunately, the Jetta's A/C is kind of crappy to begin with. Secondly, it seems as though the air maintains its coolness for only a short time before it's warm again (with A/C off and circulate on). This frustrates me to no end. It's almost as if the car is poorly sealed or something.

I drove the malibu yesterday for about 30 minutes. With the air circulation on, I turned the A/C on for all of about 2 minutes when I first started driving. THE AIR REMAINED COOL FOR THE REMAINDER OF MY DRIVE.

I guess I'd also attribute a bit of this to the fact that the dash board of the malibu is white/beige and the jetta is dark grey/black.

I am so pissed at my Jetta. So utterly disappointed, especially considering that the car's gaskets aren't even old, it's a 2008.

Please give me some thoughts...

On an unrelated note, the malibu was also superior in that it is equipped with instant mpg readout on the instrument cluster. I found that the mpgs of the malibu were quite similar to that of the Jetta as well.

SwamiSalami · 07-15-2011, 10:55 PM

oh, I forgot to add...

The jetta is dark grey, while the malibu is bright white. I'm sure this makes some kind of difference as well.

Thymeclock · 07-15-2011, 11:03 PM

Quote:

Originally Posted by dieselbeetle

I drove the malibu yesterday for about 30 minutes. With the air circulation on, I turned the A/C on for all of about 2 minutes when I first started driving. THE AIR REMAINED COOL FOR THE REMAINDER OF MY DRIVE.

I guess I'd also attribute a bit of this to the fact that the dash board of the malibu is white/beige and the jetta is dark grey/black.

There might be other explanations. Generally, the newer the vehicle, the tighter the weatherstrip seals are.

Quote:

I am so pissed at my Jetta. So utterly disappointed, especially considering that the car's gaskets aren't even old, it's a 2008.

Please give me some thoughts...

Simple: Trade your Jetta in for a new Chevy Malibu. Then you'll be happier.

SwamiSalami · 07-15-2011, 11:11 PM

Quote:

Originally Posted by Thymeclock

There might be other explanations. Generally, the newer the vehicle, the tighter the weatherstrip seals are.

Even just after a couple of years?

Thymeclock · 07-15-2011, 11:26 PM

Quote:

Originally Posted by dieselbeetle

Even just after a couple of years?

Ohh, now that's another story. But a Chevy can last a long time - especially if you are lucky and don't drive it much...

Peter7307 · 07-16-2011, 03:05 AM

Living as you do in Florida and driving a grey with a black / grey dash car in the N. American Summer with an air conditioner designed for European Summers it is hardly surprising the thing is struggling.

Isn't is obvious?

Newer car with lighter colours and designed for the conditions you are driving it in.

Peter.

camopaint0707 · 07-16-2011, 03:55 AM

So is it more fuel efficient to turn on the AC full blast to cool the car then turn it off and then back on when it's hot again or to just leave it one a lower setting to keep the car at a constant cool?

Joenavy85 · 07-16-2011, 09:58 AM

Quote:

Originally Posted by camopaint0707

So is it more fuel efficient to turn on the AC full blast to cool the car then turn it off and then back on when it's hot again or to just leave it one a lower setting to keep the car at a constant cool?

All depends on the system design. My Jeep's AC system has a pressure switch that turns the compressor on/off as needed. Some old AC systems keep the compressor on all the time the AC is on and have a recirc valve that bleeds excess pressure to the inlet side of the compressor to keep the pressure constant.

What I do is when I start driving I blast the AC with the Fan on 4, until the temp is where I want it, then I slow the fan down to 2, and adjust the hot/cold dial to where it keeps the temp constant.

camopaint0707 · 07-16-2011, 10:09 AM

That's interesting.

Joenavy85 · 07-16-2011, 10:32 AM

Also, some fan speed controllers are setup so that they draw the same current regardless of setting. My Jeep draws more current at higher settings than lower. You can test this by checking the battery voltage at different fan speeds while the engine is off. If it always draws the same amount of current, the voltage will be the same regardless of the fan speed. If the current draw varies with fan speed (higher speed, higher current draw) then the battery voltage will be lower at higher fan speeds. If you have the engine on while doing this the readings will be inaccurate due to the alternator charging the battery.