Radios and A/C? anyone who can answer?

[momontherun]

I read in the tips that not to have radio loud and not to use the a/c. How effective is turning off the a/c and riding w/windows down. Also, I've never heard about the radio thing. What's that all about? Anybody to help?

[theholycow]

You can test for yourself if you carefully control the conditions. However, I suspect that in most cases A/C is better than windows down for highway driving. In city driving the opposite is probably true.

For me, comfort comes first so I choose based solely on which way I will feel more comfortable.

If you have a factory radio, I really doubt there will be a measurable difference. People with huge speakers and amps can pull a lot of electricity. Electricity isn't free, it is still energy; it comes from the alternator, which is more difficult to turn when it has to generate more electricity.

[Improbcat]

I agree with what holycow said.

One thing I do on the highway is to turn the A/C on for a few minutes, then once it is blowing cold air turn the A/C off (but leave the fan & everything else going). It will continue to blow cold for several more minutes before slowly warming up, When it is blowing luke-warm I turn the A/C on again for a few more minutes to coll it off again. I *think* this saves gas, but my commute is so hilly & the traffic so variable it is hard to do a useful comparison.

And yeah, the stock radio is not goign to pull enough amps to make a measurable effect on mpg.

[GasSavers_StanleyD]

Windows down causes drag which reduces mpg. The faster you go the worse ot gets. AC reduces mpg but is not very dependent on speed. So for slow driving windows are more efficient, although not as comfortable. As you reach highway speeds (where there is more drag) the mpg lost due to drag is GREATER than the mpg lost due to AC. Some study showed that they are equal at about 55 mph. So if you are on highway and MUST cool down then I suggest AC. For city driving, I suggest windows.

Personally, I try to use the blower on the coldest setting and high fan speed with the AC off. If it becomes unbearable then I turn on the AC, but I use a low setting (uses compressor less) with a high fan speed. The compressor is what uses most of the gas so dont use the MAX AC setting. Try setting to a temp thats just comfortable. Your car should not be cold when people get in. If people say "Wow, this feels good, nice and chilly" or complement you on how nice your AC is, then your AC is on too high. It should just feel comfortable and not hot. Its pretty much the same with the AC at home. No need to crank the temp down to 70 degrees at home during summer. Its a waste when you feel fine at 78 degrees... The same people who crank the AC down to 70 in the summer also crank the heat up to 75+ during the winter. They want to overheat themselves in the winter and overcool in the summer.

my .02

P.S. Improv is on point. I do the same thing sometimes, although on HOOOTTT days hot air starts to blow through ten seconds after I turn off the AC.

[palemelanesian]

I don't use the radio, because it breaks my concentration. That lowers my mpg. The electrical load should be minimal, though.

[fumesucker]

Bass frequencies take far more power to reproduce loudly than the rest of the audio spectrum.. Fifty watts through decent speakers is stunningly loud, particularly in something as small as a car interior since it's almost like being inside the speaker cabinet..

As long as you don't have a monster sub shaking the neighborhood the radio, even loud, isn't going to draw enough power to worry about..

As for the AC, a lot of the energy goes into removing moisture from the air if you live in a humid climate. If you have your AC on then keep the air control on recirculate so that you don't have to continually dehumidify outside air, once the air in the cabin is dehumidifed, the AC load will drop considerably..

Dry air at the same temperature feels cooler than humid air.

Making sure the cabin is sealed so that little outside air leaks in would be one way of making sure the AC works as efficiently as possible..

Something like Insulatir on the windows would help considerably too..

http://www.johnsonwindowfilms.com/IR.php

[opelgt73]

Originally Posted by fumesucker

Bass frequencies take far more power to reproduce loudly than the rest of the audio spectrum.. Fifty watts through decent speakers is stunningly loud, particularly in something as small as a car interior since it's almost like being inside the speaker cabinet..

A true hypermiler enthusiast would throw the entire radio, speakers, wiring in the garbage and get an ipod shuffle (because it's lighter than the 80gb)..........

[GasSavers_landon]

Actually, max A/C runs the compressor less than the low setting. On max, it keeps recycling the air that's already in your car and has already been cooled. On low it must work harder to cool the hotter outside air. On my car I disabled the low fan setting so I can use the high pressure air in front of the windshield for "free" ventilation. This doesn't work on recirc. though so I must use the low A/C setting or turn on the fan.

[theholycow]

Yup, on most cars "max" or "recirc" mean the same thing.

[Jetta90GL]

Ive always wanted to try hooking a standard household air conditioning thermostat to the MAX a/c setting so that the pump only runs when needed. Set it at 72 and go..