MANIFOLD GP-CONTROL 4372886 - Caterpillar

Illustration 1 g00396227
(5) Relays for controlling fan speed (6) Relay switch for the a/c clutch (7) Control module
Illustration 2 g00396299
(7) Bar graph (fan speed) (8) Fan speed switch (decrease) (9) Fan speed switch (increase)The resistor and the relays (5) regulate the amount of voltage that is supplied to the blower motor. The relays are operated in a sequential manner from low speed to high speed. The first three relays route electricity through the resistor. Each speed is routed through a different resistance on the resistor.
The highest resistance corresponds to the low speed.
The next highest resistance corresponds to the medium low speed.
The third highest resistance corresponds to the medium high speed.
The relay for high speed bypasses the resistor. Electricity is directly routed to the blower motor.Switches (8) and (9) control the amount of voltage that is sent to the resistor.The bar graph for fan speed (7) will light accordingly. Low speed is at the bottom and high speed is at the top.Thermal protection is provided by a thermal fuse. The thermal fuse is mounted above the resistor. The thermal fuse will disconnect power in the event of extreme temperatures. The thermal fuse is rated for 300°F.