How to Fix the F3T4 Error Code on a Whirlpool Microwave

Fixing your microwave but confused by an error code? The F3T4 error code on Whirlpool models simply means your magnetron thermistor has detected overheating. This common issue can be easily remedied at home. Following some basic safety steps, most owners can troubleshoot this code themselves, saving both time and money over a service call. Let’s break down the issues that can cause F3T4 and the simple solutions to get your microwave cooking again!

What the F3T4 Error Code Means

The F3T4 error code on a Whirlpool microwave indicates there is an issue with the magnetron thermistor that is preventing the microwave from heating properly. But don’t worry – this is often an easy fix you can do yourself at home!

What is the Magnetron Thermistor?

The magnetron thermistor is a small sensor that monitors the temperature of the magnetron tube inside your microwave.

• The magnetron is what actually generates the microwaves that heat your food.
• As it operates, it gets very hot – up to 300°F!

The thermistor makes sure the magnetron doesn’t overheat.

• It is designed to shut off microwave power if the temperature exceeds 125°C (about 260°F).
• When this happens, the F3T4 error code appears on your display.
• Power will remain off until the thermistor resets as the magnetron cools back down.

So, the F3T4 code is a safety measure to prevent magnetron damage from overheating.

What Causes the F3T4 Error?

There are two common causes for the F3T4 error:

1. The thermistor itself is faulty and incorrectly reports high temps when the magnetron is at normal operating temperatures.
2. There is a wiring issue or a problem with the control board that runs the thermistor.

Safety Precautions

When working on your Whirlpool microwave, safety should always come first. Rushing repairs or ignoring precautions can lead to electric shocks, burns, cuts, and other injuries. Let’s go over some key safety tips:

• Unplug the microwave before troubleshooting or repairs. This may sound obvious, but it’s easy to forget in the heat of the moment. Unplugging cuts power to avoid electric shocks.
• Discharge the high-voltage capacitor. Microwaves store power in capacitors even when unplugged. Use an insulated screwdriver to touch the terminals and discharge stored electricity.
• Never run the microwave with the casing open. Exposed internal parts increase electric shock risk. Only operate the microwave fully assembled.
• Don’t bypass safety features. While tempting to get your appliance working again, disabling safety cut-offs like the F3T4 error can be dangerous.
• Remove the outer case carefully. Once unplugged, take off the outer case to access the internal parts. Watch for sharp edges or screws.
• Use insulated gloves and tools. When testing or handling parts, insulation prevents accidental shocks. Insulated screwdrivers are a must.
• Check for damage before reassembling. Cracked wires, leaky capacitors, or loose connectors can be hazards. Spot and repair issues to operate safely.
• Allow recently used appliances to cool. Parts like the magnetron get extremely hot. Give your microwave time to return to room temperature.
• Work slowly and carefully. Rushing leads to mistakes. Take your time and be cautious to avoid accidents. Keep jewelry or loose clothing out of the way.
• Keep children and pets away. Little fingers exploring hot appliances can get burned. Keep kids and animals out of the work area for their safety.
• Consult your user manual. Your microwave’s manual has model-specific tips for safe installation, operation, and maintenance. Give it a read.
• Handle parts gently. Don’t bend or damage any components. This can negatively impact safety features.
• Avoid exposed wires and terminals. Make sure to cap, tape over, or otherwise insulate bare wires and connections.
• Take photos while disassembling. Snap some pictures to make reassembly easier. Jot down any useful notes, too.
• Use a multimeter safely. When testing live voltage, keep your fingers on the insulated grips to avoid accidental shocks.

Stay safe above all else. Slow down, use caution, and put safety first. Paying attention to these precautions will keep you injury-free during your Whirlpool microwave repairs.

How to Troubleshoot the F3T4 Error Code

Seeing the F3T4 error pop up can be frustrating. But don’t worry – with a few simple steps, you can often fix it yourself. Let’s walk through troubleshooting this error code on your Whirlpool microwave:

Step 1: Discharge the capacitor

Microwaves use capacitors to store electricity even when unplugged. To avoid shocks, you’ll want to drain any leftover charge first.

1. Unplug the microwave from the wall outlet. Safety first!
2. Use an insulated screwdriver to touch together the capacitor’s terminals. This gives electricity a safe path to discharge through the screwdriver.
3. Slowly slide the screwdriver from one terminal to the other. Repeat this process between each terminal and the microwave’s metal chassis.
4. Double check no charge remains by touching the screwdriver to the terminals again. You should feel no shocks.

Step 2: Check the thermistor connection

The F3T4 code means the magnetron thermistor is detecting too much heat. Let’s examine the thermistor itself:

1. Ensure the microwave is unplugged. No power makes it safe to handle parts.
2. Locate the thermistor near the magnetron tube. Consult your manual for the exact placement.
3. Check where the thermistor connects to the wiring. Look for any damage, corrosion, or loose connections that could cause issues. Replace the thermistor if its connections seem faulty.
4. Use a multimeter on the resistance setting to measure the thermistor’s electrical resistance at room temperature.
5. Compare this reading to the resistance range listed in your microwave’s manual, usually around 10kΩ.

• If the thermistor’s resistance is way outside this range, replace it.
• If the reading looks normal, the issue is likely the control board. Replace the relay board instead.

Also Read How to Diagnose and Fix a Non-Responsive Microwave Touchpad

Conclusion

Dealing with microwave error codes can be confusing. But don’t let the F3T4 code intimidate you! As we learned, F3T4 means the magnetron thermistor senses overheating. This shuts down microwaves to prevent damage. But the issue is often an easy DIY fix.

By discharging the capacitor safely, checking thermistor connections, and testing parts with a multimeter, you can troubleshoot F3T4 yourself. No handyperson skills are needed! While repairs always come with some risk, taking proper safety precautions minimizes the chance of shocks or injury. Work slowly, use insulated tools, and unplug appliances before tinkering.

Tackling repairs on your own saves money and gives you confidence. Why wait around for an appliance tech when you can likely resolve errors like F3T4 with basic tools?

Does an F3T4 code still stump you? Don’t sweat it! You can always call the experts. But for many, simple troubleshooting steps will have your Whirlpool microwave heating up leftovers again in no time.

Let the F3T4 error code guide you. It’s your microwave’s way of signaling an easy fix is needed. Stay safe, take it slow, and get ready to DIY those microwave repairs!