Low Pressure Cutoff Switch; Ambient Temperature Switch - Hummer H1 Service Manual

11-34 Heating/Ventilation/Air Conditioning (HVAC)

LOW PRESSURE CUTOFF SWITCH

The low pressure cutoff switch is mounted on the receiver/
dryer. The switch is wired in series with the compressor activa-
tion circuit. Should pressure drop below the switch's setting,
the switch will open and interrupt current flow to the compres-
sor clutch. The switch will prevent damage to the system from
lack of oil flow due to inadequate charge or very low ambient
temperatures. The switch will close when the system pressure
rises to safe levels (Figure 11-48).
AMBIENT TEMPERATURE
SWITCH HARNESS
LOW PRESSURE
CUTOFF SWITCH
S11-053
Figure 11-48: Receiver/Dryer with Low Pressure Cut-
off Switch
RECEIVER/DRYER
The receiver/dryer provides storage for high pressure liquid re-
frigerant. Desiccant inside of the receiver/dryer assists in re-
moving moisture from the refrigerant. The receiver/dryer also
act as a filter, filtering out particles of debris and preventing
bubbles of vapor form entering the expansion valve
(Figure 11-48).

AMBIENT TEMPERATURE SWITCH

The ambient temperature switch is mounted on the right front
of the condenser. The switch, which monitors ambient air tem-
perature, is wired in series with the compressor activation cir-
cuit. The switch interrupts current flow to the compressor
clutch when outside temperature drop below 45°F (10°C)
(Figure 11-49).
AMBIENT TEMPERATURE
SWITCH
S11-054
Figure 11-49: Ambient Temperature Switch
RECEIVER/DRYER
CONDENSER
______________________
CONDENSER
The condenser provides heat exchange for the A/C system. The
condenser is located on the front of the radiator and cooler as-
semblies. Air from forward movement, and the engine cooling
fan is forced through the fins of the condenser, removing heat
from the highly pressurized refrigerant. Refrigerant enters the
condenser as a vapor, and exits as a liquid.
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