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Selection of which override valve motor to use (through the P310 standby power management panel)

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Control of the position (OVRD/NORM) of the right motor in the override valve (through the P310 standby power management panel).

*
Left supply fan ON/OFF and left motor of the override valve OVRD/NORM position (through the left ECC cross talk)

The left ECC outputs are similar except it does not control which motor of the override valve to use.
Fault Indication
Status messages show if a controller has a malfunction.
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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -CONTROLLER

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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -SUPPLY FANS

General
Only one of the two fans operate at a time. The right fan is primary and the left fan is the backup. Each time the airplane gets power, the right ECSMC does a test of the left fan. The right fan is set to off and the left fan is set to on. At the end of the test of the left fan, it is set to off and the right fan is set to on and tested.
The right ECSMC gives primary control of the supply fans when the airplane gets power and the left card gives backup control. When the airplane changes from air to ground, the card in control changes.
Supply Fan Control
The ECSMCs control through the right and left ECCs and the right and left power panels. Either card can control both fans. For example, these signals occur when the right card wants to turn on the left fan:
*
Right ECSMC sends FAN ON signal to right ECC

*
Right ECC sends FAN ON signal to left ECC (cross talk)

*
Left ECC sends FAN ON signal to left power panel

*
Left power panel turns on the left fan if no overcurrent condition is detected.

Both cards get information about the left and right fan overheat switches either directly from the fan or from the other card through the ARINC 629 buses.
During ground test the fans operate in the ground test sequence. See the section on equipment cooling -ground test for more information.
During normal conditions, the right fan operates if none of these conditions are true:
*
System commanded to override

*
Override valve in the override position

*
ELMS detected fault conditions (no power, open circuit breaker, overcurrent, no current, or failed relay)

*
Supply fan motor overheat

*
Converter supplemental cooling fan (VSCF fan) in test (automatic)

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Ground test -fan off command.

If the right fan stops, the left fan starts automatically.
Fault Indication
Status messages show if a fan or the circuit that controls a fan has a malfunction.
The ECSMCs monitor information from ELMS. This information helps the cards isolate supply fan malfunctions.
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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -SUPPLY FANS

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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -OVERRIDE VALVE

General
The override valve has two positions: NORM and OVRD. The valve is usually in the NORM position. The override valve has two motors: left and right. Only one motor will operate the valve at a time.
The right ECSMC gives primary control of the override valve when the airplane gets power and the left card gives backup control. When the airplane changes from air to ground, the card in control changes.
Normal Control
The ECSMC controls the primary motor through the left and right equipment cooling controllers and the P310 standby power management panel. Either card can control both motors and can set which motor is primary. For example, these signals occur when the right card wants to set the left motor as primary and make it go to the NORM position:
*
The right ECSMC sends L MOTOR PRIMARY and NORM signals to the right ECC

*
The right ECC sets the left motor as the primary motor through a relay in the standby power management panel.

*
The right ECC sends the NORM signal to left ECC (through cross talk)

*
The left ECC sets the override valve to the NORM position through a relay in the standby power management panel

*
The standby power management panel gives power so that the left motor moves the valve to NORM.

Limit switches (not shown) in each motor remove power from the motor when the valve gets to the commanded position. The same limit switches give valve position feedback directly to the ECSMCs.
　
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