Is the increased fuel consumption of using the AC linear with how much you have it kicking? Or is it an on and off situation.

So basically if its on no matter how hard or cold you have it blowing the compressor is still decreasing fuel ecomony by a given unchanged amount, or buy turning up the fan and putting the tempature guage all the way cold uses more fuel then if you turned the fan down.

I would like to understand how this works.

Thanks

 

once you turn on the defroster or A/C the A/C stays on until it is turned off.... it does not matter what the inside temp is set to on the car because it just mixes air from the outside to get the right temp in your car


It will use the same amount either way....

 

Dude he wants to know if he gets a better MPG when the A/C is off or if it doesnt matter. Or if is not as cold as it can get but you still have it on. I think it varies between the extremes for example if the **** is in the middle but you have the a/c on i think you'll get a better MPG then if you had it blasting freezing cold air. just as an example my mom's 95' taurus slows down and doesnt get as good MPG when the a/c is on compared to when it is off. Well bro hope i sorta answered ya question.

 

I thought thats the way it was too. If you had it blasting AC your MPG would be worse then if you had the AC on low, but YeuEmMaiMai says it doesn't matter as long as the AC is on regardless of how much you have it turned up you will still used the same amount of gas

 

trust me, I can read

I understood what he asked and answered it. The drag on your MPG is the same no matter what your A/C setting is because the compressor is on ALL THE TIME

reading and understanding the question at hand owns joo

 

I am not so sure. The compressor is hooked up to a magnetic clutch that I am pritty sure can verry how much slip it is enabling. If the clutch allows more slip the compressor would turn less thus using less power to turn it giving you better mpg.

 

[QUOTE
I am not so sure. The compressor is hooked up to a magnetic clutch that I am pritty sure can verry how much slip it is enabling. If the clutch allows more slip the compressor would turn less thus using less power to turn it giving you better mpg.[/QUOTE]

more or less...

its also has to do with the tempurature outside. if the exchange between the condensor and the outside air is more or less efficient it changes the efficiency of the system thus changing the amount of compression needed from the compressor thus changing the amount the compressor drags on the motor. in the traditional systems the temp ***** only controls the current through the heater coils thus it has no effect on the A/C system. in some of the newer system with auto temp control and such it may be a more complex input than that.

here read this... its for ahome system but it explains how the freon cycles.

How Your Air Conditioner Cools the Air
Central air conditioners are split systems: an outdoor unit (the condensing unit) and an indoor unit (air handler). The function of an air conditioner is to transport heat from one station to another. The vehicle your system uses to carry the heat is called a refrigerant, commonly referred to as Freon.
The compressor in your outdoor unit canges the refrigerant (or "Freon") into a high temperature, high pressure gas. As that gas flows through the outdoor coil, it loses heat and condenses into a high temperature, high pressure liquid. This liquid refrigerant travels through copper tubing into the evaporator coil. There the refrigerant expands. Its sudden expansion turns the refrigerant into a low temperature, low pressure gas. This gas then absorbs heat from the air circulating in the duct work. The cooled air is then distributed back through your house or place of business. Meanwhile, the heat absorbed by the refrigerant is carried back outside through copper tubing and released into the outside air.


[Modified by greensleeper, 11:12 PM 7/18/2002]

 

i always thought that the a/c compressor was directly hooked up to the engine with a belt, and when it was on, there was about an 8hp loss in performance. it doesnt matter how cold or warm you have it because the a/c just removes water from the air, which is why it feels really cold, but it removes the same amount of water from the air if its in hot mode too. anyway, its more efficient than rolling down your window.

 

the clutch on the a/c will not slip once it is engaged. if the clutch is slipping it is time for a new one. there is a constant drag on the engine when the A/C is turned on the compressor runs all the time. once you press the A/C button

what outside temp does is reduce power due to higher ambient air temprature your car will make more HP on a cooler day than it would on a hotter day... The drag caused by the A/C system is the same in either case

 

Honda Compressors cycle on and off, there is a temperature switch in the condensor that will shut off the compressor when the refrigerant reaches a predetermined temp and then back on when it gets warm enough. Given this fact, I would think that using the recycled air feature would improve gas mileage due to the A/C not having to cool down hot air from outside but just recooling already cooled air from inside. But I wouldn't think it would be very noticeable.

Also the ECU has the ability to shut down the compressor based on engine speed and throttle position, i.e. WOT will shut down the compressor. I used to be unfortuante to own a Pontiac Grand Am and the compressor in that car would shut off whenever you turned the wheel at a stop, so when you were parking the car it used to get really warm inside. Anyhow just my .02.

 

Just another question, anyone know if it uses more gas with the windows open or the A/C on? Is Drag from the windows, which would be constant, be better than the drag from the A/C which cycles on and off?

 

depends on how fast you are going.

 

Thanks for the info. About the windows. I say a brief study on Motor week on TV and yes it depends on speed, but if you are on the highway for example the drag created by having the windows down significantly exceeds using the AC at the same speed.

When driving around town in stop and go it probably doesn't matter much, but you'll get hotter since sitting at red lights the air isn't moving so much with the windows down.