B737 Air Conditioning Control Panel

Air Temperature (TEMP) Indicator

  • Indicates temperature at location selected with AIR TEMP source selector.

ZONE TEMP Lights

  • Illuminated (amber) –
    • CONT CAB indicates a duct temperature overheat or failure of the flight deck primary and standby temperature control.
    • FWD CAB or AFT CAB indicates duct temperature overheat.
  • During Master Caution light recall:
    • CONT CAB indicates failure of the flight deck primary or standby temperature control
    • Either FWD CAB or AFT CAB indicates failure of the associated
      zone temperature control.
    • Lights will extinguish when Master Caution is reset.

Temperature Selector

  • AUTO: Provides automatic temperature control for the associated zones. Rotating the control toward C (cool) or W (warm) manually sets the desired temperature.
  • OFF: Closes the associated trim air modulating valve.

Air Conditioning PACK Switch

  • OFF:
    • Turns pack OFF.
  • AUTO:
    • With both packs operating, each pack regulates to low flow.
    • With one pack operating, the operating pack regulates to high flow in flight with flaps up.
    • When operating one pack from APU (both engine BLEED air switches OFF), regulates to high flow.
  • HIGH:
    • Pack regulates to high flow.
    • Provides maximum flow rate on ground with APU BLEED air switch ON.

AIR Temperature (TEMP) Source Selector

  • SUPPLY DUCT: Selects appropriate zone supply duct temperature.
  • PASS CAB: Selects forward or aft passenger cabin temperature.
  • PACK: Selects left or right pack temperatures.

TRIM AIR Switch

  • ON: Trim air pressure regulating and shutoff valve signaled open.
  • OFF: Trim air pressure regulating and shutoff valve signaled closed.

Recirculation (RECIRC) FAN Switches

  • OFF: Turns fan off.
  • AUTO:
    • In-flight:
      • The left recirculation fan operates if both packs are operating unless either PACK switch is in HIGH.
      • The right recirculation fan operates if both packs are operating unless both PACK switches are in HIGH.
    • On the ground:
      • The left recirculation fan operates unless both PACK switches are in HIGH.
      • The right recirculation fan operates even if both PACK switches are in HIGH.

PACK Light

  • Illuminated (amber):
    • Indicates pack trip off or failure of both primary and standby pack controls, or
    • Indicates failure of the Flow Control Valve to open when commanded on, or
    • An incorrect pack switch configuration after takeoff – turning either PACK switch ON will extinguish both PACK lights if lights illuminated because of a configuration problem.
    • During Master Caution recall:
      • Indicates failure of either primary or standby pack control.
      • Extinguishes when Master Caution is reset.

TRIP RESET Switch

  • Push (if fault condition is corrected):
    • Resets PACK, ZONE TEMP, and BLEED lights.
    • Related engine bleed valve opens, or related pack valve opens, or related trim air modulating valve opens.
    • Lights remain illuminated until reset.