Air Conditioning
Thread Starter
Registered User
Joined: Oct 2003
Posts: 382
From: Oklahoma
Car Info: 1
Air Conditioning
I'm not particularly familiar with how the air conditioning in my car works, or how it interacts with/affects the engine.
Particularly, i'm interested in how it's powered. I've heard that if you run the air conditioning, it uses more gas. Is this at all true? Where does the A/C system draw it's power from, and if you run it, are there any negative affects on the engine or engine performance?
Particularly, i'm interested in how it's powered. I've heard that if you run the air conditioning, it uses more gas. Is this at all true? Where does the A/C system draw it's power from, and if you run it, are there any negative affects on the engine or engine performance?
Guest
Posts: n/a
The A/C is powered by a belt that is connected to a pulley off of the crankshaft. There is a power loss associated with running the A/C.
Get in your car and punch it, about half way through the boost turn on the A/C. You will notice the difference.
Brandon
Get in your car and punch it, about half way through the boost turn on the A/C. You will notice the difference.
Brandon
VIP Member
Joined: Mar 2003
Posts: 2,023
From: Phoenix, AZ
Car Info: Subaru Impreza WRX 2002
In the summer in AZ, running AC every time I step into the car, I get about 265-270 miles a tank of gas.
With the AC on just one or two days this month, I am getting 300+ miles per tank.
Not a big difference, but noticeable. Especially back when premium was $2.50 a gallon! (it is down to a sane 1.60 now).
With the AC on just one or two days this month, I am getting 300+ miles per tank.
Not a big difference, but noticeable. Especially back when premium was $2.50 a gallon! (it is down to a sane 1.60 now).
Registered User
Joined: Jan 2003
Posts: 555
From: Bethlum, PA
Car Info: silver 2.5 tr 2006MT wrx
hey there is another thing, i noticed with the temp of the air, with the ac running, floor it, the fan still runs, but the air gets warmer, i was told that the car autonatically compensates by cutting out the compressor in the ac unit when you get hweavey on the gas.
Registered User
Joined: Nov 2002
Posts: 713
From: Aiea, HI
Car Info: 02 RS
i don't think it affects the compressor since it is a closed loop system. the cool air is coming from the blower sucking air from somewhere else and blowing it across the evaporator in the cabin. when you use heat electical coils heat up the air from the blower.
Guest
Posts: n/a
when you use a warmer setting, the refrigerant in the evaporator vaporizes more slowly, and so it requires less work in the same amount of time to compress it into a liquid again. it's a pretty minor effect, though -- probably not noticeable at all...
as for the heat, i'm not sure about newer imprezas, but i know my 96 uses a heater core and not an electric heater -- coolant gets sent from the engine to a miniature radiator that sits next to the blower and heats the air coming in. the result is that you wait longer in the winter for the car to get warm
if you get in the car when it's cold, you'll notice that the heat only starts working when the temp gauge starts climbing to normal operating range. also a low-temp thermostat would make the wait longer.
on the cutting out the compressor on the gas -- the compressor clutch will disengage when engine temperature gets too high... i hadn't heard of this before, but it very well could be that newer imprezas than mine do have a feature that does the same when the accelerator is depressed past a certain point.
finally, the fan setting doesn't have any effect on the a/c system other than what i said first, where the amount of work the compressor has to do changes because more warm air is going over the evaporator and vaporizing more refrigerant when the fan is on a higher setting.
hope all the useless info helps :P especially since i just noticed the last post was like 3 weeks ago... oh well -- enjoy
as for the heat, i'm not sure about newer imprezas, but i know my 96 uses a heater core and not an electric heater -- coolant gets sent from the engine to a miniature radiator that sits next to the blower and heats the air coming in. the result is that you wait longer in the winter for the car to get warm
if you get in the car when it's cold, you'll notice that the heat only starts working when the temp gauge starts climbing to normal operating range. also a low-temp thermostat would make the wait longer.on the cutting out the compressor on the gas -- the compressor clutch will disengage when engine temperature gets too high... i hadn't heard of this before, but it very well could be that newer imprezas than mine do have a feature that does the same when the accelerator is depressed past a certain point.
finally, the fan setting doesn't have any effect on the a/c system other than what i said first, where the amount of work the compressor has to do changes because more warm air is going over the evaporator and vaporizing more refrigerant when the fan is on a higher setting.
hope all the useless info helps :P especially since i just noticed the last post was like 3 weeks ago... oh well -- enjoy
Guest
Posts: n/a
Defroster
You know what sucks... When you turn on the defroster the Air Conditoner Runs no matter what the AC Button Position. Look in the manual it says this! My honda does the same thing but it gives you the option to turn the ac off if you want. On the wrx hiting the ac button when the defrost is on does nothing. Any one know of a way to by pass that auto switch?
Registered User
Joined: Sep 2003
Posts: 119
From: Kaimuki, HI
haha
Originally posted by meilers
Not a big difference, but noticeable. Especially back when premium was $2.50 a gallon! (it is down to a sane 1.60 now).
Not a big difference, but noticeable. Especially back when premium was $2.50 a gallon! (it is down to a sane 1.60 now).
speak for yourself, its still 2.13-2.20 here...
250,000-mile Club President
Joined: Nov 2002
Posts: 4,770
From: Bizerkeley
Car Info: MBP 02 WRX wagon
Re: Defroster
Originally posted by JET
You know what sucks... When you turn on the defroster the Air Conditoner Runs no matter what the AC Button Position. Look in the manual it says this!
You know what sucks... When you turn on the defroster the Air Conditoner Runs no matter what the AC Button Position. Look in the manual it says this!
Typically when you need defrosting, the windsheild is cold, so if you were to blow moisture laden air on to the cold window- guess what- it will fog up even more!
So by charging the AC system and passing the air over the AC evaporator (the "cold" piece inside the system) your defroster is pulling moisture out of the air before blasting it onto your windows, so it can dry off the window rather than fogging it up.
You might be able to put a switch on the AC, but then your "defroster" setting would only fog/frost things up more.
Don't want the AC system activated? don't use the defrost setting, but really -using defrost without AC is not going to help at all.
Registered User
iTrader: (7)
Joined: Dec 2002
Posts: 10,029
From: Sacramento CA
Car Info: 02 Impreza WRX sedan
Run Defrost with or without air-conditioning mod. Not the type of mod for everyone, but...
http://forums.nasioc.com/forums/show...hreadid=148118
--
0==WW==0
"…axles of evil…" - george w. bush
http://forums.nasioc.com/forums/show...hreadid=148118
--
0==WW==0
"…axles of evil…" - george w. bush
VIP Member
iTrader: (7)
Joined: Jun 2003
Posts: 25,095
From: Funtown
Car Info: A limousine with a chauffer
Originally posted by chubby_one
I'm curious.. Does the A/C Compressor possibly work less or cycle on and off more slowly when you adjust the temperature control to a warmer setting?
I'm curious.. Does the A/C Compressor possibly work less or cycle on and off more slowly when you adjust the temperature control to a warmer setting?
Thread
Thread Starter
Forum
Replies
Last Post
vixhex
Engine/Power - EJ20T (pre-2006 WRX and JDM)
8
Jul 7, 2004 10:32 AM