Strange AC behavior

I've got 9000 miles now on my 2008 Mazda 3 Sport 5 door and I've noticed something very unusual about my climate control (the manual kind).

When the vent selector is set to the upper vents (all the way to the left), everything acts as expected where you can turn the AC button on and you hear the AC compressor start under the hood. You turn the AC button off, and you hear the AC compressor stop. Simple!

But...when you move the vent selector to 12:00 (straight up) which is the lower vents only, the AC Compressor turns on even when the AC button is not selected. You can turn the AC button on and off but the AC compressor never stops.

The compressor does stop if you move the vent selector to the left of 12:00 so that it's a mix of the upper and lower vents. But the AC compressor never shuts off when you move the vent selector to 12:00 or any position to the right of 12:00.

Is this how it's designed to be???
Am I going to have the AC Compressor running all winter here in the Northeast??

Or is this broken and Mazda needs to fix this.

Please advise.

Thank you!

Someone correct me if I'm wrong, but I think the idea is that the AC also works as a dehumidifier to help prevent your car from fogging up in the winter. I agree though, if I didn't press the AC button, I don't want it on. My 97 dodge neon did the same thing, except there was a trace you could cut that stopped the AC from coming on with the defroster/heat. I'm not sure if the mz3 has the same solution though.

It's not broken. It is for dehumidifying as suggested. Fresh air is also selected when the lower vent position is selected. For heat I use the face level and lower vent combined position for all my vehicles.

Clifton

If you read your manual, the AC comes on anytime the selector is at 12:00 ("feet") and higher. Furthermore, if you're on the 2 defrost modes, you can't even recycle the air. And anytime the temperature selector is turned to the extreme cold setting, the AC is turned on (light is on) and the recycling is also turned on. You can turn them off though.

This drove me nuts when I test drove the car and I almost did not purchase it because of this. BUT... there is a way to cancel this. It involves removing the heater control dials, taking them apart and soldering a couple wires. I ended up doing it and it works. I wanted to write a how-to, but no time to do a good job at it. However, I can provide a pic and instructions on how to modify the circuit board. (the hard part is to get to the circuit board and also to put eveything back together in good working order and without de-adjusting the control cables)...

Wow, the 1st gen. neons were so much easier! All I had to do was remove the trim plate over the knobs, and the trace was exposed right there. A few seconds with a good sized drill bit was able to sever the trace, no problem.

rayarnold said:

Wow, the 1st gen. neons were so much easier! All I had to do was remove the trim plate over the knobs, and the trace was exposed right there. A few seconds with a good sized drill bit was able to sever the trace, no problem.

Click to expand...

LOL I hear you - My old 2000 corolla had a little plastic thing that pushed the side of the AC switch when in defrost more - All you had to do is cut it...

Here's a pic of the back side of the Mazda3's climate control panel (manual). I circled the 2 micro-switch legs that need to be jumped... I initially wanted to totally remove the micro switches... but that would have kept the AC on all the time... Crazy engineer who designed such an annoying system!

The micro switch on the left is the heater control one - the one that turns on the AC and puts on the defrost when you turn the switch all the way to cold. You need to solder a wire on each side of the micro switch, connecting the 3 left legs together, and then connecting the right 3 legs together.

The micro switch on the right is the one that turns on the AC in "legs" and higher mode. You need to solder a wire connecting the middle and bottom leg on each side of the legs...

THEN, very important: you need to physically break the swithes on the other side so that are rendered inoperative.

Good luck to anyone who tries it.... Putting it back together is the real tricky part though...

Thanks for letting me know that my Climate Control isn't broken but just very poorly designed.

I never had to read the owners manual on how to use the AC before. But after reading that section, I do see that "Feature" documented.

Thanks for all of your input!

udder said:

...I do see that "Feature" documented.

Click to expand...

Features like this are the best kind, aren't they?