Aircon consumption

[kho686]

Dear All,

I have just installed a ultragauge to my mazda 5 and observed that by turning on the aircon, the engine load increases from 29 to 40 plus in terms of percentage on the engine load.

Is this normal?
This reading was taken when the car is idling and place in neutral gear. Aircon set at level 1 at around 25 degress celius.

 

[mazdadude]

Are you certain that you have the scangauge setup info entered properly? I am not sure what numbers are considered normal. However the A/C does make a large draw of engine power...

Maybe for comparison, you can try it idiling, in park, with the AC off, but while you wiggle the steering wheel (electric steering) and turn on the rear defroster (high amp draw) and have high beams on (high amp draw). This should put the alterator on full duty and show you what the alternator load number is on scangauge.

 

[Silentnoise713]

I had (sold) a SG2 but as far as I know UG vs. SG may or may use the same calculations for any given measure and can vary depending on the car. I recall the SG2 would display LOD (engine load) somewhere in the low teens and the added load from the AC (AC compressor runs off the main crank) would increase it by ~30%. Looking at it form a percentage, a 29->40 is about 38% increase, which sounds about right. I think the UG calculates a higher base value. Another member with a UG can confirm or you should ask in the UG forum/support. I happen to know this b/c when I had my SG2, I wondered what was the most useful gauge for efficiency – many say the LOD gauge.

This post explains it well. See posts by Old Mechanic.
http://ecomodder.com/forum/showthread.php/what-engine-load-ug-question-19078-2.html

From the UG manual :
Estimated percent of engine load.
Where engine load is calculated as

% Load = (Current Air flow)/(Peak Air Flow)
Or
% Load = (Current Engine Torque)/(Peak Engine Torque)
The method used is vehicle dependent.

 

[thaxman]

I don't know if the numbers you gave for engine loading are right, but I wouldn't be surprised at all. I lose 3-6 mpg w/the AC running - easily 20% reduction in fuel economy.

 

[kho686]

Never thought that the aircon can consume so much engine load.

 

[Secondtyme]

Air conditioning is the second largest consumer of engine power under the hood, second only to the automatic transmission. It is much more noticeable in cars with marginal power like our 5s. Often the losses can be offset with bolt on modifications like a CAI and axle back exhaust. I have had good luck on past DBW cars with a signal modifier on the gas pedal helping with the A/C anemia issue as well.

 

[ukulele]

This is why I never use my automatic climate control feature, unless maybe it's the dead middle of summer and the a/c would run anyway. It's cheaper to set the controls yourself and make sure your a/c is off unless you need it on like a rainy humid day to defog the windshield. When I look at my auto climate control push-button I see big dollar signs on it.

 

[Robotazky]

This is why I never use my automatic climate control feature, unless maybe it's the dead middle of summer and the a/c would run anyway. It's cheaper to set the controls yourself and make sure your a/c is off unless you need it on like a rainy humid day to defog the windshield. When I look at my auto climate control push-button I see big dollar signs on it.

Not sure if the '12 is the same as the first gen, but on my '09 unless you put the mode to where it's blowing out the feet and at hand level, the A/C will kick on whether the stupid A/C light is on or not. It took me forever to figure out what was going on and only because of a knowledgeable forum member was it possible to finally resolve. We keep it in the blowing configuration now unless we need A/C and it doesn't kick off and on anymore.

 

[Secondtyme]

Disabling the automatic use of the AC compressor in an auto climate controlled car is probably more trouble than it is worth. That being said, I have in the past disabled that "feature" on every car I have owned that had it. This 5 is the first car I have ever owned with auto climate control, and I'm still not sure I like it. This summer will be the proof of the pudding for me. Due mainly to my stubborness, I have been using the auto CC as "manually" as possible up to now.

 

[DKaz]

I left my 5 in auto mode all year except when it was warm in the city, then I'd roll the windows down and turn the system off altogether. The A/C cycles on and off depending on load. If it's 40C or 100F out, the compressor stays on all the time, but 25C or 80F out it cycles maybe 10 seconds on 20 seconds off.

In rainy Vancouver BC, I use the A/C more to defog windows than to keep cool. I averaged 25MPG in my 5 and am averaging 32.5MPG in my 3.

 

[ukulele]

All I know is, whenever I hit the auto CC button, I hear the ominous "Berrrp" sound and see the RPMs move suddenly (I am parked at idle). I think if it's really cold outside like below freezing it doesn't kick on but then again, unless you force it to with the windshield defog function, meaning "Hey, I can't see out the windshield so please dry the air ASAP." Actually, on my 2012 Mazda5, when you suddenly hit the windshield defog button, it kicks up the fan to max speed. Pretty cool, makes sense, I bet the guy who came up with that small but helpful idea wasn't the same guy that said, "Hey, lets let only cold air come out of the center console for the 2nd row."

 

[Secondtyme]

For those of you who have manual CC controls you probably have the ability to permanently disable the auto AC with defrost function. I know for certain that on past cars of mine (one Honda, one Subaru) the AC was engaged by a simple trip-lever set up when the air direction dial was rotated to Defrost or Feet/Defrost. If anyone feels energetic enough this spring take your manual CC panel/radio out and check to see if removing a little piece of plastic could save you some MPG driving around with the compressor engaged needlessly. And yes, I do realize that the AC compressor serves a valuable purpose in de-humidifying the air/clearing the windshield. That being said, I have always felt that if I want the compressor on I am perfectly capable of hitting the AC button myself. LOL

 

[ukulele]

For those of you who have manual CC controls you probably have the ability to permanently disable the auto AC with defrost function. I know for certain that on past cars of mine (one Honda, one Subaru) the AC was engaged by a simple trip-lever set up when the air direction dial was rotated to Defrost or Feet/Defrost. If anyone feels energetic enough this spring take your manual CC panel/radio out and check to see if removing a little piece of plastic could save you some MPG driving around with the compressor engaged needlessly. And yes, I do realize that the AC compressor serves a valuable purpose in de-humidifying the air/clearing the windshield. That being said, I have always felt that if I want the compressor on I am perfectly capable of hitting the AC button myself. LOL

I owned a 2006 Sienna, I remember, you could disable the a/c from coming on when you directed air toward the windshield/foot well, but you had to press and hold a button (forgot which one) for like 3 or 5 seconds. Problem is, when you turned the car off and on, it would not store it in memory so you have to do it everytime you started it. (hand)

 

[kho686]

All I know is, whenever I hit the auto CC button, I hear the ominous "Berrrp" sound and see the RPMs move suddenly (I am parked at idle). I think if it's really cold outside like below freezing it doesn't kick on but then again, unless you force it to with the windshield defog function, meaning "Hey, I can't see out the windshield so please dry the air ASAP." Actually, on my 2012 Mazda5, when you suddenly hit the windshield defog button, it kicks up the fan to max speed. Pretty cool, makes sense, I bet the guy who came up with that small but helpful idea wasn't the same guy that said, "Hey, lets let only cold air come out of the center console for the 2nd row."

So e "berrp" is normal?
I though my air on belt is loosen

 

[Wishmaster]

For those of you who have manual CC controls you probably have the ability to permanently disable the auto AC with defrost function. I know for certain that on past cars of mine (one Honda, one Subaru) the AC was engaged by a simple trip-lever set up when the air direction dial was rotated to Defrost or Feet/Defrost. If anyone feels energetic enough this spring take your manual CC panel/radio out and check to see if removing a little piece of plastic could save you some MPG driving around with the compressor engaged needlessly. And yes, I do realize that the AC compressor serves a valuable purpose in de-humidifying the air/clearing the windshield. That being said, I have always felt that if I want the compressor on I am perfectly capable of hitting the AC button myself. LOL

This is one of my biggest pet peeves about newer cars!! If you ever figure out a way to do this for those with the auto CC, please make sure you write-up a post!

 

[Robotazky]

This is one of my biggest pet peeves about newer cars!! If you ever figure out a way to do this for those with the auto CC, please make sure you write-up a post!

Again, you can set the air flow mode to feet and vents, not feet and defrost, and the compressor will stay off if the A/C light is off. I know it's not what you're looking for, but it is a manual workaround to at least turn the stupid thing off. My belt slips when it rains hard at 70+ mph so I get really upset having to roll the freakin' windows down in the rain to get it to defog since the defroster turns the stupid A/C on and could burn the belt up and break the car down. It's so stupid to not be able to turn the compressor off with the A/C button.

 

[m5pa]

aImport cars, for the longest time, did not turn on the A/C with defog or any other setting automatically. Maybe because initially, very few had A/C standard. Also, the re-circulation lever (now button) only did that, closing off the air inlets in the cowl (?). It's why you'll see so many older imports with the windows fogged up in the winter or during rainy, humid days. No A/C and since the recirc makes more noise, people assume it's doing more work. And most of the older cars didn't have a lockout on the recirc, so you could drive without A/C, on recirc and defrost. That's a sure recipe for fogged over windows!

Most new cars, and I mean any built in the past 10-15 years, will not let you run recirc without the A/C compressor on and won't let you select defrost in recirc period. Most auto systems do this, but most also have an off switch too. I just turn the A/C off until it's summer or the windows are foggy. I used to turn everything off when shutting down the car, but since most new cars do this automatically, I just leave everything on now. Eliminates having to remember to turn off the A/C on restart.

And yes, only having the cooling duct to the second row blow cold air was dumb. Probably due to Mazda's limited budget.

 

[Silentnoise713]

aImport cars, for the longest time, did not turn on the A/C with defog or any other setting automatically. Maybe because initially, very few had A/C standard. Also, the re-circulation lever (now button) only did that, closing off the air inlets in the cowl (?). It's why you'll see so many older imports with the windows fogged up in the winter or during rainy, humid days. No A/C and since the recirc makes more noise, people assume it's doing more work. And most of the older cars didn't have a lockout on the recirc, so you could drive without A/C, on recirc and defrost. That's a sure recipe for fogged over windows!

Most new cars, and I mean any built in the past 10-15 years, will not let you run recirc without the A/C compressor on and won't let you select defrost in recirc period. Most auto systems do this, but most also have an off switch too. I just turn the A/C off until it's summer or the windows are foggy. I used to turn everything off when shutting down the car, but since most new cars do this automatically, I just leave everything on now. Eliminates having to remember to turn off the A/C on restart.

And yes, only having the cooling duct to the second row blow cold air was dumb. Probably due to Mazda's limited budget.

Didn't know all newer cars kick in the AC when the air is set to windshield. I usually like to set it to foot and windshield to avoid air going right into my face/eyes. Most of the time, I just turn of off and let recirculating air cool the cabin. Regarding foggy windshield, I've used fog-x with success in the past. Maybe I'll need to do that again.

 

[Secondtyme]

I hate to be the one to tell you this, but if you leave the air direction on defrost/feet in your 09 Fit you WILL run the AC whenever the fan is on. Good news is that disabling that auto "feature" is very easy on that car. And back on the sunbect of Mazas, I drove mine home this evening with the AC on and was pleased to note that the car doesn't "feel" any slower.

 

[JMJinNC]

Mine's about the same - 28% load with AC on, in the teens at idle with it off. 2012 M5 Sport with Ultragauge.

JMJ