Last post on Apr 08, 2013 at 9:17 PM
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Mazda MAZDA6, Heating / Cooling, Hatchback, Sedan, Wagon
#6 of 19 Re: 2005 Mazda 6, 3.0L - A/C blows too warm, heater blows too cold. [wwest]
Jul 23, 2011 (7:15 am)
It should be pretty obvious to even a beginning HVAC design engineer that switching immediately to recirc is a mistake. The proper procedure would be to leave the system in "fresh" airflow long enough to PURGE the cabin of the atmosphere that is HOTTER than the outside, THEN switch to recirc.
That's right, lets allow the super-humid outside air to circulate into the cabin for a few moments while the occupant wants the cooler, DRYER air immediately. That makes sense...
The reason why it switches to recirc in the first place is to limit the amount of moisture in the air, as well as being more efficient by reusing the cooler air. Despite the fact that it may be warmer inside a vehicle when first starting out, the air is also not nearly as humid, and it's also something that HVAC engineers DO know.
I'll bet even your owners manual points out this mistake. It will direct you to lower the rear windows slightly for a few miles in order to purge the HOT cabin atmosphere.
Umm, nope, it doesn't. In fact, if I needed more than 30 seconds to feel at least some cool air coming from the vents, then I'd say the A/C wasn't working at all.
So it makes more sense to keep the windows down for a few miles, then kick on the A/C? Umm, no thanks. Since most car trips are no more than a few miles, why bother?
Not many of us humans feel very comfortable with dry and cool, coolish, airflow directed to our face and upper body when the human comfort equation indicates the need for HEATING.
Actually, the typical "human comfort equation", or whatever name you give it, likes to be at a certain temperature, whether or not it's the winter or summer. That's why you have a thermostat in a home, office, and now in cars, to maintain that temperature, that's all it does. You make it sound like that it goes into full A/C mode when the car reaches the set temperature in the cooler months, and kicks on the heat in the warmer months. That simply isn't the case.
Toyota and Lexus have recognized the design flaw and there is now a C-best option that prevents the system from going into cooling mode when the human comfort equation indicates otherwise.
Then it sounds like Toyota has addressed a flaw in their climate control system that isn't found in any other maker today.
#7 of 19 Re: 2005 Mazda 6, 3.0L - A/C blows too warm, heater blows too cold. [sgrae]
Jul 23, 2011 (8:02 am)
Most newer automotive HVAC systems, once the cabin ATMOSPHERE, AIR, has reached a point very close to your temperature setpoint, will "moderate" the system outflow temperature to within only a few degrees.
Change the setpoint even 2-3 degrees and the system will react by raising/lowering the outflow temperature in order to most quickly reach your new setpoint, and then moderate begins....
The radicalness of the outflow temperature swing upon a setpoint change is dependent on several not so obvious factors.
1. The OAT, the outside air temperature.
2. Sun's BRIGHTNESS, solar radiation level.
#8 of 19 Re: 2005 Mazda 6, 3.0L - A/C blows too warm, heater blows too cold. [sgrae]
Jul 23, 2011 (8:10 am)
"..Im not sure what finally fixed the problem.."
My best guess is you somehow locked the "blend" door/vane servomotor in the MAX cooling position, no airflow diverted to flow through the heater core so as to moderate the system outflow.
#9 of 19 Re: 2005 Mazda 6, 3.0L - A/C blows too warm, heater blows too cold. [wwest]
Jul 24, 2011 (7:52 am)
Everything you said prior to explaining how radical the temperature swings and the obvious factors is exactly how a modern automotive HVAC system should operate.
Wow.. I didn't even know that my car sensed the brightness of the sun.
#10 of 19 Re: 2005 Mazda 6, 3.0L - A/C blows too warm, heater blows too cold. [rswafford]
Jul 25, 2011 (9:33 am)
Awesome! Great to hear it helped.
My A/C has been working great ever since I jiggled the wires, and I'm never going back under my dash as long as things are working. One wrong touch of a wire could screw up the A/C again.
#12 of 19 Help A/C prob pls! Only 2 mos Warranty Remains!
Jun 04, 2012 (11:34 am)
09 Mazda6 S Grand Touring 3.7L
Just got the car 1 week ago, & already I need to find what is causing the following. I only have 2 months of factory b-b warranty, and I want to make sure the issue is addressed properly....especially if expensive factory parts are involved! Im thinking this is happening to others:
* after 4 hours of drive time, with AC at maximum blower velocity and minimum temperature and NOT on “Auto”.
* AC Blower velocity significant reduced.....especially in drivers side.
* AC temperature not even “cool”
* pulled over opened hood while engine running and AC still on.
* The refrigerant line, leading into firewall, was frosted over.
* turned AC off and waited 5 minutes.
* investigated evaporator area under dash
* Water was pouring out of Evap Box, and down onto the floor boards. ( no drain hose? )
* Water was running out onto unidentified electronic control module and wire harness!
* No Protective Loom or Jacket on wire harness either...... 8 \
* Water came into contact with Heater Core OR “High Side (hot side) AC line”, then dripped on passengers feet, burning them.
* water droplets were spitting out of passenger-center vent.
* Next day AC "seems to work"
Have only seen mentions of "cooling fan problems" on this car. Could this be the issue? I was driving Highway speeds the whole time....so never say engine temp go up.
Can this cause the refrigerant line to frost over?
Someone please point me to another post if it rings a bell.
Im trying to avoid being placated with jive nonsense, or worse, for <60 days, when I will fully own the "real" problem with this car. Thank you in advance!
#13 of 19 Re: Help A/C prob pls! Only 2 mos Warranty Remains! [natb1]
Jun 04, 2012 (2:00 pm)
Your system is low on refrigerant. Could be due to many reasons. You need to recharge the system and check for leaks. Read your warrenty to see what is covered, don't just quote b-b warrenty.
#14 of 19 I think I found the issue
Jun 05, 2012 (5:28 am)
Thanks, but I think I found the issue.
I found the cabin filter last night (first car Ive had with one) and it was caked with yard debris. The "grating/screen" for recirculation is large....like a chain link fence. I even found a leaf the size of a 50 cent piece. Im 95% this is the problem, because it would certainly explain the frosting and excessive water after thawing. I would think the drain line could be more effectivie though....water running out of the box and onto the floor? Perhaps it was condensing on the outside of the plastic housing? Hmmm..
I just need to take it for a long drive on a hot day.
I will report any developments for the benefit of others.
#15 of 19 Re: Help A/C prob pls! Only 2 mos Warranty Remains! [natb1]
Jun 05, 2012 (6:52 pm)
I do not know whether this is directly relevant to Mazda6 or not, but for Mazda3 there was a TSB for AC freezing over and starting to blow warm air after driving for extended periods of time at highway speeds with AC on and fan on low. I do not know what the resolution of that was, and my car has done this once, but if anything, the best remedy for future situations like that would be to crank up the fan a bit.