Whirlpool · Microwave Moderate

F3T — Exhaust Fan Thermostat Fault

The exhaust fan thermostat is reading outside the expected range (below 41°F / 5°C or above 140°F / 60°C). The vent fan over the cooktop won't kick on automatically in response to heat.

Keep using it?
Yes, with caution
DIY difficulty
Moderate
Verified against
applianceaid.com ↗

How to fix it

  1. Confirm normal kitchen temperature (above 41°F, below 140°F). Let the microwave equalize.
  2. Power down at the breaker for 1 minute and retest.
  3. Unplug the unit, locate the exhaust fan thermostat per the tech sheet, and check continuity at room temp.
  4. Replace the thermostat if it reads open or wildly out of spec.
  5. If a new thermostat doesn't clear F3T, suspect the appliance control board.

Why it happens

Typical signs: F3T on the display · Vent fan doesn't auto-start when the cooktop below is hot · Microwave cooks normally otherwise

  • Failed exhaust fan thermostat Cycles open or shorts with age.
  • Wiring open at the thermostat Inspect the harness in the vent path.
  • Ambient temperature truly out of range If the kitchen is freezing or above 140°F, the code is valid — let the unit reach normal temp.

Parts you may need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • Whirlpool microwave exhaust fan thermostat Common replacement
    Amazon →

More Whirlpool microwave codes

AccuPop Fail AccuPop Fail — Popcorn Sensor Fault Demo Demo Mode — Not Heating Door Door / Open Door Closed — Safety Reminder F1E4 F1E4 — Appliance Manager or Power Relay Fault F1E5 F1E5 — Inverter Internal Fault F2 F2 — Keypad / Control Fault

All Whirlpool codes → All microwave codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: applianceaid.com.