Chevrolet 2007 TrailBlazer Owner's Manua page 191

The passenger's side temperature setting also
resets and relinks to the driver's side temperature
setting if the vehicle has been off for more
than three hours.
Outside Air Temperature Display
A new outside temperature reading will be
displayed if the vehicle has been off for more
than three hours. If the vehicle has been off for
less than three hours, the old temperature
reading may be displayed because underhood
heat is affecting the true outside temperature.
Underhood heat can also affect the outside
temperature while the engine is running.
It may also take several minutes of driving
before the display updates to the actual
outside temperature.
Automatic Operation
AUTO (Automatic): When automatic operation
is active, the system will control the inside
temperature, the air delivery mode, and the
fan speed.
Use the steps below to place the entire system
in automatic mode:
1. Press the AUTO button.
When AUTO is selected, the air conditioning
operation and air outlet mode will be
automatically controlled. The air conditioning
compressor will run continuously when the
outside temperature is over approximately
40°F (4°C). The air inlet will normally be set to
outside air. If it's hot outside, the air inlet will
automatically switch to recirculate inside air to
help quickly cool down your vehicle.
2. Set the driver's and passenger's temperature.
To find your comfort setting, start with a
72°F (22°C) temperature setting and allow
about 20 minutes for the system to adjust.
Turn the driver's or passenger's side
temperature knob to adjust the temperature
setting as necessary. If you choose the
temperature setting of 60°F (15°C), the system
will remain at the maximum cooling setting.
If you choose the temperature setting of
90°F (32°C), the system will remain at the
maximum heat setting. Choosing either
maximum setting may not cause the vehicle
to heat or cool any faster.
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