What F3C Means
Over-the-Range Microwave: KitchenAid publishes for F3C "There may be a problem with the Cavity Temperature Thermistor or the associated wiring." A thermistor changes resistance with temperature, and this one watches the cooking cavity. The control uses it to know that the space it is heating is behaving, and a value that cannot be a real temperature stops the cycle rather than being acted on.
Common Causes of F3C
- A cavity thermistor failed or drifted out of range
- Thermistor wiring damaged or unseated
- A control channel no longer reading the thermistor
🔧 One Safe Check You Can Try
Switch off the cooking surface underneath and let it cool before you stand at the appliance at all - an over-the-range unit puts your forearms directly above a range, and a burn from a hot hob is the injury that actually happens while people are troubleshooting a microwave. Then power the unit down by switching off the circuit breakers for one minute, power it back up, watch the microwave for one minute to see whether the code returns, and verify the microwave operates.
⚠ Why You Shouldn't Go Further Than That
- Losing the cavity temperature reading means losing the check that would catch the cavity running hot, which matters more on an appliance mounted above a range.
- The high-voltage capacitor inside a microwave can hold a lethal charge after the unit is unplugged and the display is dead, so the inside of the cabinet is not an owner check at any point in this process, whatever the code turns out to mean.
- An over-the-range unit hangs on a wall bracket above a cooking surface and is bolted through the cabinet above it; taking it down is a two-person job over a cooktop, and dropping it is the usual way this goes wrong.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.