AD30 Underground Articulated Truck Machine Electrical System Heating and Air Conditioning Caterpillar


Heating and Air Conditioning
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AD30 Underground Articulated Truck Machine Electrical System [RENR6921]
ELECTRICAL AND STARTING SYSTEM
WARNING GP
AD30 Underground Articulated Truck Machine Electrical System Backup Alarm
AD30 Underground Articulated Truck Machine Electrical System Heating and Air Conditioning



Illustration 1g00999542

Heating and air conditioning circuit

The components of the heating and air conditioning circuit are the fan speed switch, the relay, the air conditioning control knob, the air conditioning thermostat switch, the fan motor, the refrigerant pressure switch, the compressor clutch solenoid, and the pressurizer fan motor.




Illustration 2g00997228

Cab

(1) Fan speed switch

(2) Air conditioning control knob




Illustration 3g01009993

Internal components of the air conditioning unit

(1) Fan speed switch

(3) Air conditioning thermostat switch

(4) Fan motor

(5) Relay




Illustration 4g00997230

Right side view of cab

(6) Pressurizer fan motor




Illustration 5g00997231

Right side view of engine

(7) Refrigerant pressure switch

(8) Compressor clutch solenoid

With the key start switch in the ON position, 24 volt power is supplied from the batteries via circuit breaker #8 to the fan speed switch and to the relay.

Fan speed switch (1) is a four position switch which controls the operation of fan motor (4) and pressurizer fan motor (5). When the fan speed switch is turned to the LOW, MEDIUM or HIGH position, 24 volt power is supplied to air conditioning thermostat switch (3), relay (5), fan motor (4), and pressurizer fan motor (6) .

The air conditioning thermostat switch controls the required level of cooling and protects the system from over-cooling. When the air conditioning thermostat switch contacts are closed, 24 volt power is supplied to the relay coil. The relay will energize and 24 volt power will be supplied to refrigerant pressure switch (6). When the air conditioning system is charged with refrigerant, the refrigerant pressure switch is closed. 24 volt power is then supplied to energize compressor clutch solenoid (7). This activates the compressor causing the refrigerant pressure to rise.

When the refrigerant pressure increases higher than the set value of the refrigerant pressure switch, the refrigerant pressure switch opens interrupting the power supply to the compressor clutch solenoid. The compressor is now deactivated and refrigerant pressure will slowly decrease.

When the refrigerant pressure decreases to the normal set value of the refrigerant pressure switch, the refrigerant pressure switch will close and the compressor will be activated.

If the refrigerant pressure decreases below the normal operating pressure, the refrigerant pressure switch will be open. This will interrupt the power supply to the compressor clutch solenoid and the compressor will not operate. The system will not activate until the system has been serviced.

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