2004 GMC Envoy Owner's Manual - Page 146

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. Since underhood heat can also affect the outside temperature while the engine is running, it may take several minutes of driving before the display updates to the actual outside temperature. OFF: Press this button to turn off the entire climate control system. Outside air will still enter the vehicle, and will be directed to the floor. Press the AUTO button, the mode button, the fan arrows, or either temperature knob to turn the system on. MODE: Press this button to manually select the air delivery mode to the floor, instrument panel, or windshield outlets. The system will stay in the selected mode until the mode button is pressed again or the AUTO button is pressed. Driver's Side Temperature Knob: Turn this knob clockwise or counterclockwise to manually raise or lower the temperature on the driver's side of the vehicle. The display will show the temperature setting decreasing or increasing and the word DRIVER will appear on the display. This knob can also adjust the passenger's side temperature setting simultaneously if the two zones are linked. The words DRIVER and PASS will then appear on the display. Passenger's Side Temperature Knob: Turn this knob clockwise or counterclockwise to manually raise or lower the temperature on the passenger's side of the vehicle. The display will show the temperature setting decreasing or increasing and the word PASS will appear on the display. The passenger's temperature setting can be set to match and link to the driver's temperature setting by pressing and holding the AUTO button for three seconds. Now, by adjusting the driver's side temperature setting, the passenger's side temperature setting will follow and both DRIVER and PASS will appear on the display. 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 two hours. 3-26