How to get the HVAC to blow fresh air

[banzairx7]

At some point I had stumbled upon the procedure for getting the auto HVAC system to blow unheated outside air but can't find it now. There was a procedure of turning on the auto function and setting things a certain way then shutting off. Right now I'm about ready to smash the center console of this car. Between blowing hot air and turning on the AC all the time I hate the HVAC system in this car. Who at mazda thought it would be a good idea that when you have the temp set to 60 and it's 75 degrees out the car should blow heated air?? And why when I set the vents to blow on my feet does the AC come on? It doesn't mean I need my feet dried, it means my feet are cold. That last one I did figure out a bypass. The AC doesn't come on with it set to vent and floor then I just close the dash vents. Still annoys the hell out of me.

 

[TitaniumSpd]

No offense but it sounds like you are using it wrong or the system needs a recharge. If you have the auto set to 60 it should blow cold air. If not, you should probably check the A/C level. And when you set the venting to the footwells, it should just blow through from the engine bay. If it actually turns on the AC it sounds like you have an electrical problem with your HVAC system.

 

[Jay Davidson]

If you want the dash vents to blow in unheated and un-cooled air directly from outside, all you have to do is set the auto HVAC to "OFF" and turn on vent (as opposed to recirc). Simple as that.

-Jay

 

[banzairx7]

Ti- The AC works fine. I'm talking about when in manual mode. Also set your mode to the foot vent and you'll notice the engine idle will raise. That's the AC kicking on. The AC light doesn't come on but the AC is on regardless.

I know I'm not crazy since it was doing the warmer air thing today. I had the fan set on 2, temp set at 60, AC off, Ambient temperature was ~75. There was at least a 10 degree difference between the outside air and the air coming out of the vents as measured by very accurately calibrated hand-o-meter. IE sticking my hand in front of the vent then out the window.

I should also note that my girlfriends 2009 Mazda5 does the same exact things. Warm out the vents and AC kicks on when set to the floor vent.

 

[banzairx7]

Found a thread on another forum about this problem. It was actually dealing with the 2nd gen 6's but it got me thinking. Their issue was pulling in hot air from the engine bay. I looked into how our cars pull air into the car and the cause of my problems became very clear. There are two sets of grills that allow air to get pulled into the car located in front of the windshield. There is one on the passenger side located under the hood, this one is closest to the inlet of the fan. There is a very small gap at the back of the hood for this vent and a much easier path for air from the fender area to it. This area at the back of the fender is open to the engine bay. The weather stripping for the hood stops a few inches short of the fender itself. The other is to the drivers side center of the car and is completely open to outside air. I turned on the HVAC fan full blast and you could feel the air being pulled into the passenger side vent and almost no air movement from the center one. The problem is the HVAC system pulls in a good amount of heated engine bay air through the passenger side vent. The problem is worse when moving since there is air flowing from the engine bay by the vent into the fender.

To test out my theory I used some painters tape and blocked the passenger side vent and took it for a drive. Voila! I now have ambient temperature air flowing from my vents. How could Mazda have screwed something up so obvious(once you know what to look for)? Also there was no noticeable drop in air flow from one vent being blocked.

Offending passenger side vent-

Center vent-