auto climate control question

barryWest

Member
I've noticed when using the auto climate control on our 2008 mazda5 that the light for the A/C turns on automatically. I find this a bit odd in the winter when I've got the temperature set pretty high; I normally end up turning the A/C off since it just doesn't seem right. Is the compressor or whatever the A/C needs actually running when the light is on?? That would seem to be a waste of gas in the middle of the winter.
 
It runs all the time whether the light is on or off - at least that's what I've found on the CX-7. It's just one of those things you have to know will happen when you choose automatic climate control over manual.
 
Yep. The A/C compressor runs, albeit not continuously, when the ACC is on. Needs it to run so it can do it's thing to get it to the right temp when it needs it. I personally think it's a pain myself since I'm all about best MPG possible. You could just set the mode/temp/fan speed manually and that would keep the A/C off (except for Defrost mode).

However, it should be noted that A/C in the Mazda5 seems to be pretty efficient as far as MPG goes. I think before I only noticed a 1 or 2 MPG ding by having A/C on. I'm planning to run a test on the next 6 tanks of gas... I'm going to go 1 tank ACC on, 1 tank manual (including A/C off), and repeat 2 more times... then I'll average out the three ACC tanks and the three manual tanks and see what if any difference in MPG is there.

Also, I can't cite a source, but I've read at least one or two places that the A/C should be run at least once either per week or month (I forget) or else the system could eventually seize up. So in this regard the ACC keeps the A/C system 'exercised'.
 
One thing I noticed is that if I changed any settings from Auto, the inside of the car fogs quite easily so I just put it in auto and adjust the temperature accordingly.
 
Yep. The A/C compressor runs, albeit not continuously, when the ACC is on. Needs it to run so it can do it's thing to get it to the right temp when it needs it.
However, it should be noted that A/C in the Mazda5 seems to be pretty efficient as far as MPG goes. I think before I only noticed a 1 or 2 MPG ding by having A/C on. I'm planning to run a test on the next 6 tanks of gas... I'm going to go 1 tank ACC on, 1 tank manual (including A/C off), and repeat 2 more times... then I'll average out the three ACC tanks and the three manual tanks and see what if any difference in MPG is there.

Interesting, so it still runs in ACC mode even when you turn the A/C off. Oh well, maybe that's par for the course when it comes to auto climate control, I can't really say since this is the first vehicle I've owned with that feature. For me the ACC is not a big deal up north here in the winter, but I can see myself using it more often in the summer months when I turn on the air conditioning.

Anyway, I'd be very interested in hearing about your test results, thanks.
 
Yeah, my first ACC car too. I hate using the A/C unnecessarily but the ACC is so damn nice, set it and forget it. From about October - March I virtually never touch any buttons on the climate control except for defrosting. In the summer, however, I frequently have the windows open so I shut it off then.

Just note, my wife and I swap cars to carpool into work, so it'll be at least 2 months before I can burn about 70 gallons of gas for the results. ;) I could update after only two, but I'm reluctant to as an averaged number for both would be more accurate.
 
I have not done as detailed analysis but after the break-in on the 08 I'm getting almost the same mileage with the Manual A/C (06) than with the Auto A/C (08) (+/- 10 miles, give or take). Auto in the 08 is always on (mostly for defrosting). The extra 10 miles usually go in favor of the 06, but also my wife does not rev up or accelerate as much as I do, so I guess that is where the difference lies.
 
When i put the A/C in auto, i take off the a/c. It is still on the auto mode though. And i think the A/C is off cause i was driving this way when temperature was warmer and rainny and the car fog up fast. As soon i push the a/c on, the fog disappeared, and this is what dry air from the a/c does usually. Anyway in the winter the MPG is bad real bad.
 
When i put the A/C in auto, i take off the a/c. It is still on the auto mode though. And i think the A/C is off cause i was driving this way when temperature was warmer and rainny and the car fog up fast. As soon i push the a/c on, the fog disappeared, and this is what dry air from the a/c does usually. Anyway in the winter the MPG is bad real bad.
Hm, interesting. This does seem pretty conclusive that you actually can shut the A/C off while the ACC is on. However, my experiences with turning the A/C off (while the ACC is on) is that I can still hear the A/C compressor kick on and off. I'll have to play around with it some more I guess...

And yes, winter temps and fuel blend drops MPG like 5-10 mpg regardless.
 
When i was reading the owner manual there was something about the fact that with the light A/C off it was still running as auto climate. But for the compressor running or not i never pay attention.
 
I did try to have the ACC on and off the A/C. The compressor didn't run for sure.
Put back the A/C on with ACC on, the compressor kick on and off.
 
I tried this...

1) Press ACC to activate
--> A/C comes on automatically
2) Press A/C to turn off
--> ACC light turns off along with A/C light

07 Touring = Fail. :(
 
I can have ACC activate with A/C off on 2008 GT
 
A/c

Owners manual seems to suggest that the A/C will not run when the ambient temp. is lower than 32 degrees F regardless of the setting.
 
Owners manual seems to suggest that the A/C will not run when the ambient temp. is lower than 32 degrees F regardless of the setting.

There was a big discussion at Fitfreak.net about this. whenever, control knob is at defrost mode. a/c automatically kicks in . some were suggesting if the outside temp is very cold, a/c will not engage but i personally think a/c is "on" when ever in defrost mode.

However, i don't see much difference in MPG .. i guess a/c system in newer cars work "smart" and "efficient" to give you the best of both worlds.
 
I have a ScanGauge trip computer http://www.scangauge.com/ connected to my 2008 Mazda5 GT and on three occasions this week, I turned on the AC with and without the ACC when the temperature was below -10C . In all three cases, I monitored the engine fuel intake and it made absolutely no difference which means the compressor didn't engage.

When the outdoor temp is near 0C I'll do the tests again.
 

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