Use car blower fan or external USB fan?

[MurrayRothbard]

Want to limit AC use to save fuel. Wanted to get a little $10 USB clip fan from ebay to blow on me in the car. But I realized I can just jus the cars fan on neutral air temp (white color, not hot or cold) and that would accomplish the same I believe.

Does using the car cabin fan blower still drop FE significantly? Or would a USB clip fan be better?

CAR is a Toyota corolla 2006

[Piotrsko]

Short answer: probably. Long answer: my VW cycles the compressor periodically, yours may not. the onboard fan draws much more current than the clip on plugged into the charge port. Can you see this change in fuel consumption? Maybe but it will be in the measurement noise values.

[MurrayRothbard]

So cars (yours atleast) cycles the compressor if the fan is on? Or just do it regardless? Do most cars generally do this? My corolla 2006 has a fan toggle between "off" and how fast it blows, then another toggle for the temperature.

Not really familiar with AC operations or how it works exactly. How involved is your cars compressor cycle? Why does it do this and how much does it impact FE?

[Ecky]

On the air mixer, blue means outside air temp, white (in the middle) is a mix of heated and outside air. Putting the slider in the middle will always result in warmer than outside air as it's essentially a blend lever.

If you have a separate button for A/C, turning it off will prevent the compressor for coming on - unless you have the car on the defrost setting, which overrides that and turns on the compressor. VW may do things differently, but in every Honda or Mazda I've ever owned, the A/C compressor does not come on if you have the A/C button off.

Regarding energy used, the blower fan relay is generally around 30 amps, which would allow up to 350 watts. They also typically use an inefficient resistor array to control speed, meaning running it at the lowest speed doesn't save as much power as you'd expect.

On the other hand, you aren't going to get outside air into the car with one of the tiny in-cabin fans. It will just circulate the air already inside, which I find gradually heats up the longer you're in the car. I

I've never been able to notice a fuel economy difference with the blower running, but it's' not an insignificant electrical load.

[JSH]

The problem I find with just running the fan through the car's vents is that the air coming out of the vents is warmer than the outside air as it is heated up by the engine compartment heat. Even my Bolt EV has this problem.

It makes me wish for the days of small wing windows that could be used to scoop air from the outside.

Another option is a roof vent like rally cars use.

[JRMichler]

I measured the power draw of the heater blower in my old 06 Canyon: https://ecomodder.com/forum/showthre...raw-18678.html.

The current draw for the heater blower ranged from 2.7 amps on the lowest setting, to 12.5 amps on the highest setting. That thread also has some calculations for the effect of electrical power draw on the fuel economy.

[Gasoline Fumes]

If you never want to use the A/C, you can remove the compressor clutch fuse or relay. Then you can set the temp knob all the way down without the A/C kicking on. If the A/C pulley is easily visible, you can look at it with the temp knob at different settings to see if the A/C compressor is actually turning on.

[Tahoe_Hybrid]

Originally Posted by MurrayRothbard

Want to limit AC use to save fuel. Wanted to get a little $10 USB clip fan from ebay to blow on me in the car. But I realized I can just jus the cars fan on neutral air temp (white color, not hot or cold) and that would accomplish the same I believe.

Does using the car cabin fan blower still drop FE significantly? Or would a USB clip fan be better?

CAR is a Toyota corolla 2006

This will damage the USB port most likely find something that will operate directly from the 12v cig