m9431

One of the "features" that I really dislike about my new Mazda3 is that the A/C turns on when heat or defrost is selected on the mode control. Emailing Mazda customer support was not helpful. Yes, I know that the A/C is supposed to remove moisture, but this is not the best solution because the moisture gets trapped in the system's air dryer and will blow back in to the car later after setting for awhile forcing you to run the A/C again. Besides, if I want the A/C on to dry the air, I can simply turn it on with the A/C control. Having the A/C on when I don't want it wastes gas and robs engine power. You cannot turn off the A/C when heat or defrost is selected. So this 'feature' is not a smart one, even though many other manufacturers also do this.

The mode control switch activates a microswitch to turn on the A/C. To defeat, you'll have to take the dash apart to get to the mode control and microswitch. Anyone know how to take the dash apart to access this switch?

Until then, removing fuse F26 stops the compressor from turning on. At least this is a temporary fix during cooler weather so that the A/C will not turn on when heat or defrost is selected.

Hopefully Mazda will eliminate this feature and realize that drivers are smart enough to use the A/C switch when they need or want A/C!

Mazda3Citd

I have a 2007 mazda3 diesel with automatic climate control. I would think it's the same system as in gasoline cars.

When I push the 'auto' **** the AC will come on (green light on AC button). When I then push the AC button the AC will turn off (I can hear the compressor stopping and the light goes off) and the light on the auto **** turns off but when it is cold outside (like 10 C/ 50 F) the heater still seems to be working in automatic mode. As the cabin warms up the fan will go on lower speeds and also it will select/alternate the outlets by itself.

m9431

Thanks for your reply. Mine does not have an auto button. Seems that I cannot turn off the compressor when heat or defrost is selected. My solution was to remove the fuse for the compressor; I'll reinstall the fuse when hot weather arrives. Interestingly, less moisture becomes trapped in side the car now because the A/C air dryer now has much less moisture trapped in it.

I'm curious how you like your Diesel? Does it have a turbocharger? My other car is a VW diesel--a great car!

Mazda3Citd

I love it!!

It is a 110 hp 1.6 turbodiesel with variable turbovanes, intercooler, double overhead camshafts and 16 valves. The engine is built by PSA (french) and also used in Ford, Citroen, Peugeot, Volvo and in the new Mini diesel.

Although 110 hp doesnt sound like much it is still fairly quick as all the torque, 240 NM (177 ft/lbs) is already available at 1750 rpm. There is also an overboost from the 3rd gear on that will give 260 NM torque. The engine can also easily be remapped to around 130 hp and 300+NM torque.

My average fuel consumption at 60k (since new) is 5.7 liters/100 km thats 17.5 km/liter = 41 MPG (US) . I may add that I am not a slow driver.

When I drive a steady 120 kmh (75 MPH) on the GPS, which is 130 kmh (81 MPH) on the speedo, it uses around 5 liters/100 km, thats 47 MPG (US).

I have a 55 liter tank but when the guage says empty and the fuel light is on I can tank no more then around 45 liters. I guess there is a 10 liter 'reserve' as you don't want to run a (modern) diesel on empty. The fuel system then needs to be primed again and thats not something you do easily without the tools. I can go about 800 km / 500 miles on 45 liters.

m9431

As I expected! Sounds like a great engine in a fun car. I heard no word on Mazda's plans for diesels in the USA. My '02 VW diesel has 222,000 kM (132,000 miles) on it without any problems and still looks and runs great while achieving 48 to 53 miles per gallon even at 80 MPH. Requires little maintenance, too. I'm told that I can probably run it up to 300,000 miles. Actually I choose my '3' for some "fuel diversity." While another VW TDI diesel would have been great, VW currently does not offer a new Golf diesel here. I test drove most all small car models and the Mazda compared with VW on "fun factor," easily beating Honda, Nissan, and Toyota. And, I got a great deal on my '3' so I was sold on it, but I could not give up my little diesel.

I love a diesel's torque; the low RPM's at highway speed, and pulling hills in 5th gear without downshifting are remarkable. I'd love to drive a Mazda diesel, too.

Here's to hoping that Mazda brings great diesel cars like yours to the USA!

Mazda3Citd

I think diesels are coming your way :-)
This article explains a bit (found it with google) http://www.autobloggreen.com/2007/07...he-us-in-2010/

You may know it already but the 24 hour of Le Mans has been won (overall!) by diesels lately.

m9431

Yes, saw that article some weeks ago. I just wonder if the car manufacturers will follow through, especially as gasoline has fallen in price recently and diesel still costs more. Most Americans do not know much about diesel and many think of the old diesels, smell, hard starting, etc. But time will tell. By the way, a great site for VW diesels, and some others, is: www.tdiclub.com

Keep on torque'ing....

Mike N

[QUOTE=m9431;405804] Anyone know how to take the dash apart to access this switch?

[QUOTE]

Yes, the dash is really simple to take apart, but the HVAC switch is a sealed unit. I've got some pictures of the assembly, but can't post from my desk top?

m9431

I wish I could see how the dash comes apart. Does the switch have wires coming from it?

Mike N

Sent you a bunch of info and some pictures, hope it helps...

m9431

Mike, your the greatest... Thanks for the info and photos!

Mike N

I just checked this on an 2010 and I was able to switch the A/C off during heat mode, unlike previous models.

chris24

I, too, do not like the AC to be controlled by the mode switch. My old car did the same thing when placed in "Defrost" and the windshield would sweat on the outside and I would have to use the WWipers or turn the heat on (in the summer?)
I almost took the car in for warranty repair because I heard the AC cycling, until I read the owners manual. For some stupid reason, the AC also comes on when the mode control is set to the "Floor" position as well as "Defrost".
I do not think this "manual control" AC system has a humidity sensor to turn the AC off if not needed. Nor are you able to turn off the AC via the indicator switch if you feel that you don't need AC (ie. the windows are f'in open) unlike the "auto control" system referred to in the thread. What were the engineers thinking, this kills my fuel economy.
I would also like to defeat this absurdity but will wait until the warranty runs out before I tear the center dash console apart. Maybe we should start a movement of "smart" owners and demand a "fix" for this on the Mazda 3.
My suggestion until then is to leave the mode control in the position just CCW of "Floor" for floor heating (or ventilation) or the "Bi-level" settings. To keep my windshield from fogging up on chilly mornings I direct the two outboard dash vents up at the glass until the car interior warms upand select "Upper" on the mode control.
If you really want to open up the dash, check threads for radio replacement or got to a local after-market garage. Hope this helps. CHRIS24liks2ZZ

cb474

I have a 2006 Mazda3 that I got use last year. I've also notice the AC compressor cycling on when I'm running the heat and even when I'm just running the vent in the coolest setting, but with the AC off. It doesn't seem to make a difference what the temperature setting is or what positioni the mode control is in. The compressor runs more when I'm using the AC. But it seems like in any setting, once the fan is on, it always runs at least a little bit. It's really annoying and does seem like a total waste of gas. My Mazda 3 has the automatic fancier climate controls and I find them totally annoying also. All of the "convenience" features just end up doing things I don't want to do. And to do what I want to do takes more steps. Ugh. Perhaps I will resort to the fuse solution, though I wish there was something more elegant.

m9431

Seems like Mazda 'saw the light' and corrected this for 2010, based on what I read here. That doesn't help us pre-2010 owners and it appears that it's a big deal to try and re-work the micro-switch, even though-for lack of time I did not take the dash apart to determine what needs to be done. For now, I just remove the A/C fuse and re-install it for summer.