National Crane 1-21-2019 Control # 104-07 3-9
1400A SERVICE MANUAL ELECTRIC SYSTEM
HYDRAULIC OIL COOLER
The hydraulic oil cooler (Figure 3-8) is mounted on the boom
rest. An electric fan in the cooler housing circulates air
through the cooling core when the hydraulic oil reaches 49°
C (120° F).
Not all return flow is routed through the oil cooler. A check
valve 206 kPa (30 psi) limits the flow through the cooler.
Since hydraulic oil is thicker when it is cold, less oil is routed
through the cooler when it is cold than when it is hot.
The cooler electrical system is made up of the following:
• Electric Fan
• Fan Relay
• Temperature Senor
The temperature sensor is located in the cooling core and
energizes the fan relay when the hydraulic oil reaches 49° C
(120° F). The fan relay is in the VEC module and turns the
fan on when energized. If the fan does not run when the
hydraulic oil is hot check the temperature sensor, relay, and
fan motor.
NOTE: The fan runs constantly if the sensor fails.
HYDRAULIC TEMPERATURE SENSOR
WARNING LIGHT
A warning light on the crane cab console is illuminated when
the hydraulic oil has exceeded the maximum recommended
temperature. A sensor in the hydraulic swivel port #4
monitors the temperature of the return oil and turns the light
on when the hydraulic oil reaches 96° C (205° F). If the light
fails to illuminate, check the light and the temperature sensor
in swivel port #4.
Item Solenoid
1 Passenger Side Stabilizer
2 Passenger Side Beam
3 Driver Side Beam
4 Driver Side Stabilizer
1
2
3
4
FIGURE 3-7
NOTE: Solenoid as
viewed from the
rear of the truck.
FIGURE 3-8
Fan
Temperature
Sensor
Fo
r
Reference
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