Maybe this will help you understand the system a little better. again i think this should be stickied somewhere. oh well.
Someone should sticky this as this is maybe one of the most discussed topics on the board. I know ove copy and pasted it atleast 3 times. i am 99.9 pecent certain this is the way it operates.....
Say it is 90* outside. You want the air in the car to be cold. You could set the system to 76*. The system sees that you want the air to be colder, so it blows fully cooled air at the highest fan speed from the dash vents until the cabin starts to cool down, at which time it gradually slows the fan speed. When the temperature is finally reached (which it rarely is) the fan speed will be at the lowest or second lowest speed, and the system then begins to alternate between warm and cold air to hold the temperature at the set 76* and not to let it get warmer or colder than that. It will even alternate between dash vents and floor vents to keep the balance of air temp.
Say it is 35* outside. You obviously want the air in the car to be warmer. Say the system is set at 76*, same as in the summer example. When you first start the car, the fan speed will be at the first bar, barely blowing, until the engine generates enough heat to actually heat the air coming from the vents. Once this happens, the system will turn the fan speed all the way up and direct airflow to the floor due to the fact that warm air rises. This way the cabin will warm in a more uniform manner, as opposed to the air coming from the dash vents, and heating the upper part of the car while leaving the floor still fairly cool. Once the cabin nears the 76* setting, the fan speed will gradually decrease. Once the temperature is reach, the system will alternate between cool and warm air, and switch between floor and dash vents to maintain the set temperature.
Full-Auto:
Automatically adjusts fan speed
Automatically adjusts air direction
Automatiaclly adjusts air temperature blown
I understand this mode to be the same weather or not the AC is selected to be on or off. The system still behaves totally automatically, however the car may not cool down as fast inside if it is hot outside with the AC off, just like with any AC system. (if you press the AC button to turn off the AC compressor, the display will not light up the "AUTO" light because Mazda got stupid and didnt use the "ECO" light given to us on the display. This would have allowed the display to read "AC AUTO" or "ECO AUTO"depending on if the compressor was on or off.)
Semi-Auto 1:
Automatically adjusts fan speed
DOES NOT automatially adjust air direction
Automatically adjusts air temperature blown
Enter this mode by starting in full auto mode, and telling the system what you want the air direction to be. In this mode, the display will not light up the auto light because it isnt fully automatic. The system will remain in this mode untill you tell it to return to Full-Auto mode by pressing the auto button (which will reactivate the AC compressor if it was turned off), or by going into Full-Manual mode by adjusting the fan speed useing the fan speed knob.
Semi-Auto 2:
DOES NOT automatically adjust fan speed
Automatically adjusts air direction
Automatically adjusts air temperature blown
Enter this mode from Full-Auto mode by adjusting fan speed by useing the fan speed knob.
Full-Manual:
DOES NOT automatically adjust fan speed
DOES NOT automatiaclly adjust air direction
Automatically adjust air temerature blown (except when 60* or 90* selected)
Enter this mode from Full-Auto by adjusting the fan speed useing the fan speed knob (far left knob) and telling the system where you what you want the air direction to be. If you want totally cold air, adjust temp to 60. If you want totally hot air, adjust the temp to 90. If you want air of any temp in between, adjust it to that number. The system will do very little to see that the temperature is reached. That part is now up to you. For example, if you select 60, the car will constantly blow the coldest air possible. If you select 72*, the system will vary temperature to acheive 72*, but will not vary fan speed or air direction because you have told the system where you want the air to come from and at what speed. If you select 90*, you will get constant hot air reguardless of interior temperature. In this setting, you will need to tell the system how you want the fan to operate as well as the air direction.