*
Right and left equipment cooling supply fans off

*
Ground test command to override.

The override valve relays in P310 standby power management panel are fail safe to make the valve go to the OVRD position. This makes sure the override valve will go the OVRD position if the ECCs or the ECSMCs have a malfunction.
Override Indication
The EQUIP COOLING OVRD advisory message shows and the OVRD light comes on when the equipment cooling override valve is in the OVRD position.
Fault Indication
Status messages show when a motor or the circuit that controls the motor have a malfunction.
The ECSMCs monitor information from ELMS. This information helps the ECSMCs isolate malfunctions with the override valve.
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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -OVERRIDE VALVE

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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -DUCT PRESSURE SENSORS

Functional Description
The duct pressure sensors measures the pressure in the equipment cooling ducts. The E5 and converter supplemental cooling fan duct pressure sensors send information to the right ECSMC. The E4 and flight deck duct sensors send information to the left ECSMC. The cards use the low pressure information for indication purposes only.
Low Pressure Indication
The EQUIP COOLING advisory message shows when there is a low pressure condition on the ground for more than five minutes. The advisory message also shows when there is a test of the converter (CONV) supplemental cooling fan and there is a low pressure condition for more than fifteen seconds. There are no flight deck indications for a low pressure condition when the airplane is in the air.
Fault Indication
Status messages show when a sensor has a malfunction.
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A/C -EQUIPMENT COOLING -VENT FAN -FUNCTIONAL DESCRIPTION

General
The vent fan gets primary control from the right ECSMC when the airplane gets power and backup control from the left ECSMC. When the airplane changes from air to ground, the card in control changes.
Control
The ECSMCs control the fan through the EEU in the left power management panel and the ELCU in the left power panel. Either card can control the fan. These signals occur when the right card controls the vent fan on:
*
The right ECSMC sends a FAN ON CMD signal to the EEU in the left power management panel

*
If the EEU does not find a malfunction, it sends a FAN ON CMD signal to the ELCU in the left power panel

*
The ELCU turns on the vent fan.

Both cards get information about the fan overheat switches. The left card gets it directly from the fan. The left card shares the information with the right card through the ARINC 629 buses.
During a ground test, the test controls fan on/off control logic. See the section on equipment cooling ground tests for more information on the ground test.
During normal conditions, the fan operates continuously if all of these conditions are true:
*
Vent valve or forward cargo heat valve is open

*
No vent fan motor overheat

*
System is not commanded to OVRD

*
Override valve is in the NORM position

*
Left or right supply fan is on

*
Ground test does not command the fan off

*
ELMS does not find a malfunction (no power, open circuit breaker, overcurrent, under current, failed relay).

Fault Indication
Status messages show when a fan motor overheats or the circuit that controls the fan has a malfunction.
The ECSMCs monitor information from the ELMS. This information helps the cards isolate malfunctions with the vent fan.
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A/C -EQUIPMENT COOLING -FWD CGO HT & VENT VLVS -FUNCTIONAL DESCRIPTION

General
　
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