The short answer on F3T4
F3T4 means there may be a problem with the magnetron temperature thermistor or its associated wiring. The magnetron is the part that generates the microwaves, and its thermistor lets the control protect it from overheating. Microwave cooking may stop or be refused while F3T4 shows, and because the magnetron sits beside the unit's high-voltage parts, every check beyond a reset and clear vents belongs to a technician.
Error codes
Reference| Code | Meaning |
|---|---|
| F3T4 | There may be a problem with the Magnetron Temperature Thermistor or the associated wiring. |
Behaviour that comes with F3T4
- Microwave heating stopping mid-cycle with F3T4 — The control halts the magnetron when it loses the temperature reading.
- Microwave functions refused at the start — A reading missing even before the magnetron runs.
- F3T4 after long or back-to-back cooking — Heat building around the magnetron, or a connection opening as it warms.
- The cooling fan running loudly or not at all — A cooling problem that may sit alongside the thermistor fault.
Why F3T4 appears, in likelihood order
- The magnetron temperature thermistor — First: the documentation names it, and it lives on one of the hottest parts in the unit.
- Its wiring or connector — Second: heat close to the magnetron ages terminals and insulation.
- Restricted cooling — Third, and not on the documented list: blocked vents let heat build up around the magnetron and its sensor.
- A one-off misread — Last: a code that clears with a reset and never returns.
Diagnosing F3T4: the order that saves time
- Check the vents — Blocked vents are free to clear and rule out a cooling problem.
- Let the unit cool and reset — A code triggered by a passing condition clears with a restart.
- Note the pattern — At the start of a cycle or only after long use tells the technician where to look first.
- Have the thermistor, wiring and cooling tested — A technician opens the unit safely, discharging its capacitor before testing anything.
Clearing F3T4 and checking it safely
- Clear the vents — Remove anything stored against the vent openings or on top of the unit.
About 2 min
- Let it cool, then reset — Leave the unit off to cool, then unplug it or switch off its breaker for a minute and restore power.
Tools: breaker panel accessAbout 15 min
- Retest with water inside — Heat a microwave-safe cup of water briefly; never run the unit empty.
Tools: microwave-safe cupAbout 3 min
- Leave the cabinet closed — The magnetron area holds the unit's high-voltage parts, and nothing inside is an owner repair.
Safety on this appliance
Safety
Unplug the unit or switch off its breaker before cleaning it, and never remove its outer cabinet: the high-voltage capacitor inside can hold a lethal charge long after unplugging, and it sits beside the magnetron this code concerns. Never defeat the door switches or try to run the unit with the door open, and never run it empty, which can damage the magnetron.
Reset or repair: where the line is
Call if F3T4 returns once the vents are clear and the unit has cooled and been reset, or if microwave heating stops repeatedly. Every part this code names sits next to the high-voltage circuit, so the repair is always a technician's; they discharge the capacitor, test the thermistor and wiring, and check the cooling fan and vents.
More Amana oven code pages
Model coverage and limits
This reading of F3T4 applies to Amana units whose control reports the magnetron temperature thermistor or its wiring with this code, as the table states, which are units with a microwave function. The thermistor's location and the protective behaviour vary by model, and a model-specific page, where one exists, is the better guide. None is listed for F3T4 yet; begin at the Amana oven code index below.
The Amana oven code list
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