Hvac Controls; Mode Dial - Hummer H1 Service Manual

11-36 Heating/Ventilation/Air Conditioning (HVAC)

HVAC CONTROLS

REAR DEFROST (OPTIONAL)
Figure 11-52: HVAC Control Panel
The HVAC system is operated using a control panel. The panel
has controls for:
• Blower speed
• Air temperature
• Mode
• Air conditioning
• Rear window defrost (Optional)
Status for all of the controls is shown using painted marks on
the faceplate of the control panel. Operation is based on driver
input, no automatic function is incorporated. Controls for the
HVAC system are based on (vacuum) door motors and water
valve controls, and (electric) blower motor and temperature
door motor controls (Figure 11-52).
Blower Speed Dial
The blower speed dial has 4 positions.
• Low
• Med 1
• Med 2
• High
The operator selects the fan speed by rotating the dial clock-
wise (Figure 11-53).
Figure 11-53: Blower Speed Dial
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HVAC CONTROL HEAD
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Temperature Dial
The temperature dial controls the temperature of the air exiting
the HVAC unit. When the dial is rotated to the cold position,
the water valve is shut off and the temperature door isolates the
heater core. When the dial is rotated to the HOT position, the
water valve opens and the temperature blend door directs air
through the heater core. Between COLD and HOT, tempera-
ture is regulated by changing the amount of air that passes
through the heater core (Figure 11-54).
Figure 11-54: Temperature Control Dial

Mode Dial

The mode dial allows the operator to direct air to a selected
area. When the driver rotates the dial clockwise and chooses a
mode, vacuum is sent to the vacuum motors that must close
(Figure 11-55).
NOTE: When the main HVAC unit is without vacuum, air will
be directed to the defrost and floor vents, and fresh air will be
used. The blower motor on the HVAC unit will not function if
the mode dial is set at the OFF position. When the dial is posi-
tioned on an A/C position, the compressor clutch will be acti-
vated.
Figure 11-55: Mode Dial
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