What is easier on your A/C? - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 08-06-2007, 09:06 PM   #1
Registered Member
 
Join Date: Sep 2005
Posts: 144
Country: United States
What is easier on your A/C?

So, speaking from a fuel efficiency standpoint, what's the better way to run your A/C? Turn the fan speed dial down or raise the temperature dial? Or is once your A/C engaged, it pretty much wastes the same energy no matter what?
__________________

__________________
Scouring the country for an excellent condition Civic VX
Flatland2D is offline   Reply With Quote
Old 08-06-2007, 09:14 PM   #2
Registered Member
 
omgwtfbyobbq's Avatar
 
Join Date: Jul 2006
Posts: 1,516
Country: United States
Ehm, for cars that just have an off/on AC clutch, you might as well turn on the fan at full blast so you can get as much cooled air in, versus turning the fan on low and having the AC do the same amount of work for not as much cooled air. If you have any hills on your commute that you can go down in gear above your idle fuel cut, turn on the AC for free cooling.
__________________

__________________
Quote:
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
omgwtfbyobbq is offline   Reply With Quote
Old 08-06-2007, 09:31 PM   #3
Registered Member
 
GasSavers_Red's Avatar
 
Join Date: Nov 2006
Posts: 513
Country: United States
Send a message via MSN to GasSavers_Red
I usually set my fan to max recirculate, run the AC for a few minutes, turn it off till it heats up again, then cycle it back on. If your car is insulated well enough I figure one could get back with bursts of AC
__________________
GasSavers_Red is offline   Reply With Quote
Old 08-07-2007, 04:44 AM   #4
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
Raising the temperature dial likely leaves that comnpressor running, and allows hot water to flow through the heater core. Not very efficient for normal cooling use...

I leave the fan up pretty high, with the air recirculating in the cabin, and cycle the compressor off and on manually.
__________________
Bill in Houston is offline   Reply With Quote
Old 08-07-2007, 09:48 AM   #5
Registered Member
 
GeekGuyAndy's Avatar
 
Join Date: Jul 2007
Posts: 160
Country: United States
I'm glad I have manual controls (set the fan speed, not the temp) and I just run AC full blast for a minute than leave it off as long as I can. Lately I was just dealing with it being a bit warm, or open both drivers side windows 2". I found that with both windows open the air circulated out instead of just passing by the window. If I open the drivers front and passengers rear theair crosses through even more.
__________________
GeekGuyAndy is offline   Reply With Quote
Old 08-07-2007, 10:21 AM   #6
Registered Member
 
Join Date: Aug 2007
Posts: 107
Country: United States
I love this site. It is full of cheapskates like me who think alike

I use my air conditioning as air brakes alot. Only run it while slowing down. I leave the fan on recirculate and just cool the ac core down momentarily. I will always turn it off while accelerating. And if I need to cool it down a little bit I will only do so when at a steady speed or slowing.

I hate to hijack this thread but how hard would it be to put a vaccum activated control on the A/C On button so you could set it to come on at above a certain vaccum level? So if you are only pushing on the gas pedal less than a certain amount the A/C comes on.
FritzR is offline   Reply With Quote
Old 08-07-2007, 10:31 AM   #7
Registered Member
 
brucepick's Avatar
 
Join Date: Feb 2007
Posts: 722
Country: United States
Location: Connecticut
I used to have a/c....

Anyway, about fan speeds, remember that cars have flow through ventilation, so your cooled air is being blown out of the car by the fan. Once you get the car down to a halfway comfortable temperature you're best off with the lowest fan speed setting you can tolerate.

Unless you set the ducts to "recirculate", the faster you run the fan, the more air you're blowing through the car. Kind of like using your home a/c with the vent control set to "open" (or a window open). You'll feel lots of nice cold air on your body but you're paying to cool that air down. If you keep the car windows shut and can get by with the fan on low speed I'm pretty sure the compressor will have to run less.
__________________
Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.

Now driving '97 Civic HX; tires ~ 50 psi. '89 Volvo 240 = semi-retired.
brucepick is offline   Reply With Quote
Old 08-07-2007, 10:53 AM   #8
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
Ya, that is why I leave it set on recirc. Well, that and the whole humidity thing...
__________________
Bill in Houston is offline   Reply With Quote
Old 08-07-2007, 11:29 AM   #9
Registered Member
 
Join Date: May 2007
Posts: 231
Country: United States
Quote:
Originally Posted by FritzR View Post
I hate to hijack this thread but how hard would it be to put a vaccum activated control on the A/C On button so you could set it to come on at above a certain vaccum level? So if you are only pushing on the gas pedal less than a certain amount the A/C comes on.
That would be challenging. You would need a vacuum switch that opens under no vacuum, and closes under high vacuum. It would need to be adjustable so you could set it to allow operation while cruising, and this would require that you measure the vacuum under different conditions to see what level you would need the switch to trip at. Or, you'd have to drive and adjust for a couple of weeks until it was working the way you wanted. And, it isn't necessary on modern cars, depending on make and model the AC is controlled by the computer, and the computer cuts compressor power under WOT conditions.

Actually wiring it in is easy enough, you just mount the switch near the compressor, cut one of the compressor control wires, attach both ends to the vacuum switch, then run a vacuum line to the intake manifold. You need direct exposure to the intake itself, not a ported line.

Might also look at a thermostat that would cut power to the compressor when the temp is cool enough. Automobile systems use a mix of full AC and heater core air to adjust the air temp coming from the vents, meaning that you are cooling the air, then heating it back up again. By setting a thermostat inside the car (needs to be a DC powered operated thermostat, home thermostats sometimes use AC power) you can run the temp at max cool, then control how often the compressor cycles by the thermostat. Kinda like the idea of using a deep freeze as a fridge. You'd wire the thermostat in the same way, the only difference being you'd use a relay in the AC line, and a control line off the thermostat. This way you only have to run a single 18ga wire to the engine bay, not two 12ga wires to go from the AC wiring to the thermostat and back.
Telco is offline   Reply With Quote
Old 08-07-2007, 04:45 PM   #10
Registered Member
 
Mentalic's Avatar
 
Join Date: Jun 2007
Posts: 121
Country: United States
On every car I have checked the compressor is cycled on an off by the pressure switch on the low pressure side of the evaporator. So when heat is adsorbed into the evaporator the low side refrigerant pressure rises, when the pressure rises sufficiently enough to activate the switch, the compressor runs. Once the evaporator is cooled sufficiently the corresponding low side pressure would have dropped and the compressor is switched off by the same switch.

Having said the above the most efficient way to continuously run the AC is on the lowest fan speed possible and also split the air between the floor and upper vents if you can. The reason to split the air is to help keep the return air as cold as possible to reduce the A/C run times. You do want to run on recirculate at all times and never ever turn on the heat. If its too cold on low shut it off and roll down the windows.
__________________

__________________
Mentalic is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Jetta Hybrid bates General Fuel Topics 13 10-17-2013 05:15 AM
Fuely keeps on modifying my fuel-ups nimi9 Fuelly Web Support and Community News 3 10-16-2013 03:23 AM
Add Vehicle Nicknames to Facebook Posts meissen Fuelly Web Support and Community News 2 08-13-2012 08:16 AM
Alternate input methods? eileen Fuelly Web Support and Community News 5 08-07-2008 10:45 AM
Interesting Solar Power Business Matt Timion General Discussion (Off-Topic) 3 01-24-2007 09:14 PM

» Fuelly iOS Apps
No Threads to Display.
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 10:15 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.