I started having a strange problem today. My A/C simply acts crazy, like idiot is adjusting it, not sensors, when in auto mode.

It's 2008 Mazda6 (2nd generation), European model, A/T (2.0 engine). Today was 35 Celsius (like 95 F) outside. I got in my car, started driving, and noticed A/C is cooling car too slowly. I glanced and noticed that it's blowing at mild power (3 out of 7 or 8, what's the top power?) at 19 C temperature setting, with external circulation ON.

I tried decreasing temperature over steering wheel, but it didn't respond. I can move the "dash" left/right to pick what I want to adjust, but moving controller up/down results in nothing. It's working in other modes (audio/etc), so button is OK.

Then I adjusted it manually, decreasing temperature to 15.5 resulted in 4/7 fan power and still having external circulation enabled (ON)! At 15.0 it would start blowing at full power, closing external circulation (OFF).

Adjusting to anything above 15.0 results in huge decrease of power, and opens up external air circulation. Even in dual mode, putting one to 15.0 and other to 15.5 gives same bad result.

At 26-27 it starts blowing hot air (heating), not sure if it usually does that as I rarely put it that high during craziest summer temperatures!

It's not big malfunction, I can survive with it for a while, but I need to know what's causing it, since auto mode is very convenient and I'm used to it + I am so used adjusting it all over steering wheel controls, I get lost when clicking, but nothing happens.

I tried stopping car completely (engine off/key out) and trying again, thought it's some temporary malfunction, like "software getting stuck", but didn't help. Also checked two A/C fuses (in engine and driver's compartment), but seem OK to me.

Any ideas or experiences with something similar? This is completely strange to me, I've driven Mazdas forever, but never saw something like this.

And, I know that taking it to dealer/service will (probably) solve the problem, but I would like to know what kind of problem I'm looking at, as even authorized Mazda services here have little clue about something that's a bit less common than usual; especially when it comes to electronics

If it matters (I know it does not): I'm from Croatia.

 

It almost sounds like an internal temp sensor failure (except for the control issue), maybe it thinks the inside of the car is cold enough or too cold (which would explain the heat), take it to the dealer if its still under warranty. You can try to unhook the battery for a few mins and hook it back up, this should clear the computers memory (you will have to reset everything) and see if it works then.

 

Hey, thanks for suggestion. I was thinking along same lines, but was afraid to disconnect battery, due to various stories about how "not suggested" that is, but it just didn't make sense to me, since even in manual it's described how to disconnect/replace it.

So, disconnected, left few minutes like that, connected back, all working properly, including steering wheel controls. Everything in car was reset (radio, consumption, averages, etc), but all working good now, awesome!

The only thing was blinking DSC OFF light afterwards, but manual says, to put key to ON position and rotate wheels to far right, then far left and that's it.

 

Glad its working now and that it was so cheap and simple, those are always the best fixes.