CUTTING EDGE 4T6388 - Caterpillar

Illustration 1 g02351113
(1) Relays (Compressor, Condenser Fan Motor, and Blower Motor) Note: The three relays (1) for the compressor, condenser fan motor, and blower motor are identical. In order to determine which relay is for which component, identify the color variations of the wires on each of the relay connectors.Compressor Relay
Illustration 2 g02501376
Compressor Relay Diagram
(P) Connector A relay is used to control the clutch on the refrigerant compressor. The compressor relay is turned ON/OFF by receiving a ON/OFF signal thermally controlled at the control panel.Condenser Fan Motor Relay
Illustration 3 g02502036
Condenser Fan Motor Relay Diagram
(U) Connector A relay is used to control the fan for the refrigerant condenser. When the compressor relay is ON and the pressure switch is ON, the condenser fan motor is turned ON. If either the compressor relay or the pressure switch is turned OFF, the condenser motor is turned OFF.Blower Motor Relay
Illustration 4 g02502098
Blower Motor Relay Diagram
(F) Connector A relay is used to control the power to the fan control for the blower motor. The blower motor relay is turned ON with a signal from the control module. Power voltage is supplied to the blower motor through the fan control.Relay Specifications
Illustration 5 g02391357Type of relay ... 24-4PECoil resistance ... 320 OhmsVoltage range ... 20 VDC to 30 VDCNote: Be careful, there is a polarity in the coil side of the relay.Check the continuity between terminals (3) and (4) under the following conditions. When 20 VDC to 30 VDC is applied between terminals (1) and (2), continuity exists between terminals (3) and (4). When no voltage is applied between (1) and (2), continuity does not exist between terminals (3) and (4).