Bump since I actually did this and added preliminary instructions in the second post.

 

Couldn't have said it better myself... I just got my RX-8 a few weeks ago, and I was dumbfounded as to why the compressor was coming on without the A/C light lit...
My last car (Scion tC) did this at the defrost mode as stated in this thread, but I couldn't figure out why just having the vent set to 'floor' would kick it on!
In both the Scion and the Mazda, the A/C light does NOT come on when it is doing it's 'secret' on mode....I think that is BS. If your going to come on automatically per mode, at least give us a on/off status light! I am smart enough to determine when I need to de-humidify!!! Living in AZ, that is NOT very often... but a nice floor breeze to supplant windows down driving (day cool air or night warm air) is all I want. I rarely use A/C even when 100+ deg out...

Thanks for the work around..

-C

 

Dude you have way too much time on your hands. Good info zoom.

 

I'd make sure I had the upgraded starter first...

 

in my 2001 honda i did someting very similar and about 2 years later a tech told me to hold down a few buttons and turn the key on and off and the defroster light blinked, and voila it made the ac not run when the defroster was on.. I'll bet there's an option to do it on the mazda somehow too.

 

Whoa !! I am glad this thread got started, because until I read it I had no idea that the AC on/off control was so complex, worse still the indicator light does not come on when the AC is on !! How daft is that??
Having read through every post and gone from disbelief to understanding, then back to confused I checked my 2004 AT and distilled it all down to the following:
1) Air to windscreen in any combination = AC ON like it or not. That's pretty standard and what most of us are used to, doesn't need the AC light IMHO. (But would be nice).
2) Air to floor ONLY = AC on like it or not. That's a new one on me, I assume there is a reason but I don't get it yet.
3) Air to anything other than listed above can be with or without AC, drivers choice by pressing the AC button to illuminate it.

If I got this right then the only NEW / UNUSUAL thing I have to worry about is that air to floor will kick in the AC, Did I get that right ??
I can live with that.

 

Zoom, any info as to whether or not that's possible with our cars?

 

Bump to this thread.

I know it's old and perhaps the answer lies in another thread (I couldn't find it).

Is there a way to defeat the automatic A/C and only have it come on when the A/C button is toggled?

 

No way to turn it off, that I know of.

You could do what I do, pull the underhood fuse marked "a/c clutch" then it thinks it's still in control.

I still cycle the a/c once a month in winter, to lube the seals.

S

 

Bah. Thanks for the response, StealthTL. I'll give the fuse trick a try.

 

I suppose one could put an additional relay in the the path of power to the compressor clutch, and thereby disable the AC via a switch in the cabin.