A320 VENTILATION CONTROL PANEL

BLOWER & EXTRACT pb

AUTO : When both pushbutton switches are on AUTO:

• On the ground before the application of TO power, the ventilation system is in open circuit configuration (closed configuration when the skin temperature is below the ground threshold).
• On the ground after the application of TO power, and in flight, the ventilation system is in closed circuit configuration.

OVRD : When either pushbutton switch is on OVRD:

• The system goes to closed circuit configuration.
• Air from the air conditioning system is added to ventilation air. (The blower fan stops if the BLOWER pushbutton switch is in the OVRD position).

When both pushbutton switches are on OVRD: 

• Air flows from the air conditioning system and then overboard.
• The extract fan continues to run.

FAULT light : Lights up amber (and ECAM activates)

• in Blower switch, if :
  • blowing pressure is low (on ground external horn sounds)
  • duct overheats (on ground external horn sounds)
  • computer power supply fails
  • smoke warning is activated
• in Extract switch, if :
  • extract pressure is low (on ground external horn sounds)
  • computer power supply fails
  • smoke warning is activated

CAB FAN pb

• ON : The two cabin fans are on.
• OFF : The two cabin fans are off.