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cloak33
09-30-2011, 02:04 PM
Not sure if this is normal or not, but I've never experienced it in any other car. I've got an 07 Mazda 3i with A/C. When the A/C is on I know it's normal for the compressor to kick in often, but what sounds like the compressor continues to kick in even with A/C off and just the fan on. When the fan is off I don't notice it.

Anyone know what this is?

Thanks
TheMAN
09-30-2011, 02:20 PM
if you have the vents sent to defrost or floor, the AC will run no matter what
cloak33
09-30-2011, 02:44 PM
No kidding? Why is that? So basically the A/C is running all winter long cause of the defrost being on?
TheMAN
09-30-2011, 02:47 PM
the AC works as a dehumidifier, without it being on, it'll take forever to clear up the windows

your questions is one of the most asked questions on any mazda forum... probably in the top 10 :)
I think the manual might have a mention of this too
cwp_sedan
09-30-2011, 02:56 PM
+1

It's also good to run the a/c compressor once in a while in the winter to keep the system oiled.
cloak33
09-30-2011, 02:59 PM
Makes sense. Does this put the same huge drag on the motor that the normal A/C does when the actual button is pressed on?

(Clearly my search skills are lacking :( )
cwp_sedan
09-30-2011, 03:00 PM
Makes sense. Does this put the same huge drag on the motor that the normal A/C does when the actual button is pressed on?

(Clearly my search skills are lacking :( )

Yes it does put an extra load on the system, just like it does in the summer. I try to keep it off as much as I can.
cloak33
09-30-2011, 03:32 PM
That's pretty disappointing. That must really effect mileage. Anyone find ways of keeping the windows defrosting without it on? Lastly, why would the floor setting cause it to come on, or are you referring to the defrost/floor combo option?
cwp_sedan
09-30-2011, 03:34 PM
The 12 o'clock setting to the far right is all defrost/compressor engaged. That's just how it's set up unfortunately.
greaves82
09-30-2011, 11:21 PM
The 12 o'clock setting to the far right is all defrost/compressor engaged. That's just how it's set up unfortunately.

Didnt know that, maybe thats why my compressor is always running
thanks!!
slam525i
10-01-2011, 11:03 AM
I've watched the OBDII data output with and without the A/C compressor on. You can see the idle engine load goes from 12-14% to about 25%, and the throttle opens by an addition 1% or so. So, yes, it does increase fuel burn but not by much.. Much safer to let the climate control do it's thing than to drive around with a fogged windshield.