B737 Window Heat Panel

Window OVERHEAT Lights

• Illuminated (amber): Overheat condition is detected.
• Note: OVERHEAT lights also illuminate if electrical power to the window(s) is interrupted.

Window Heat ON Lights

• Illuminated (green): Window heat is being applied to selected window(s).
• Extinguished:
  • Switch is OFF, or
  • An overheat is detected, or
  • A system failure has occurred, or
  • System is at the correct temperature.

WINDOW HEAT Switches

• ON: Window heat is applied to selected window(s).
• OFF: Window heat not in use.

WINDOW HEAT Test Switch (spring-loaded to neutral)

• OVHT: Simulates an overheat condition.
• PWR TEST: Provides a confidence test.
• Note: Refer to Supplementary Normal Procedures for Window Heat Test procedures.