What Error Code F7 Means on Your Whirlpool Microwave

Is your microwave oven displaying an F7 error code? This usually indicates a problem with power getting interrupted by the internal magnetron tube. Without consistent power, the magnetron can’t generate the microwaves needed to cook foods. With some basic troubleshooting steps, you can diagnose the cause, resolve the F7 Whirlpool microwave error, and get your microwave heating properly again.

If you find out that you need any replacement parts for your appliance while you’re troubleshooting, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

The information in this article may not apply to your specific appliance model. We recommend consulting your manufacturer’s documentation or contact us with any questions.

What causes the error code?

Microwave ovens operate by using a high-voltage transformer called a magnetron. This tube converts electricity into concentrated microwave energy.

These microwaves are directed into the cooking cavity, causing food molecules to rapidly vibrate and heat up. This is how microwave ovens can cook and reheat foods so quickly.

For this process to work properly, the magnetron needs a consistent power supply to generate continuous microwave output. If there is any power failure in electricity reaching the magnetron, it can’t proceed with the proper operation.

The F7 error code is the microwave’s way of signaling there is a power interruption to the magnetron circuit. This is typically caused by an issue with one of the following oven components:

• Cooling fan
• Magnetron 
• Door interlock switches
• Wiring and connections
• Electronic control boards

Without fixing the F7 error, your microwave won’t produce any energy to actually cook the food!

Safety precautions

When working on any appliance, remember to keep safety first. Here are some tips to keep in mind: 

• Always power off and unplug your appliance or switch off the circuit breaker before attempting any maintenance or replacement work. This keeps you safe by preventing any risk of injury from electric shock.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with bare wet hands. Make sure the work area is completely dry.
• Check your user manual to see if there are specific installation or safety instructions for your part or appliance. 
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• If the appliance has recently been used, give it plenty of time for any heating parts to cool down before working on it. 
• Take pictures or make a note of wiring terminals or other connections before disconnecting to prevent any problems with reassembly.

When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.

Microwave safety 

Microwaves contain high-voltage parts and have the capacity to store voltage even when they’re disconnected from a power source. Please be very careful while working on a microwave’s internal parts to avoid electrocution, which has the potential to cause serious injuries or death.

• Always unplug the microwave before troubleshooting or making repairs.
• Discharge the high-voltage capacitor before working on high-voltage parts to eliminate the risk of electric shock. Do not continue if you are uncomfortable or unfamiliar with this process. 
• Never attempt to run the microwave while its casing is open or when internal parts are exposed. Always completely reassemble the microwave before testing or using it.
• Never attempt to bypass any microwave safety features.
• Never run the microwave empty. Use a glass of water for test running. 
• Removing a microwave from over the range is a two person job due to the weight and potential for damage. Follow manufacturer installation instructions for reinstallation over the range after repair. 

Discharging a microwave capacitor 

IMPORTANT: Carefully follow the correct handling and discharge procedures since exposure to the voltage levels inside a microwave can potentially cause severe injury or death. Prioritize safety at all times and follow the instructions and recommendations provided by the manufacturer. If you do not feel comfortable discharging a capacitor, do not attempt to do it yourself.

1. Unplug the microwave from the power source.
2. Grab a screwdriver with good insulation on the handle to protect against electric shock.
3. Gently touch the insulated screwdriver blade to one terminal of the capacitor.
4. Slowly and gently slide the screwdriver forward until it reaches the other terminal of the capacitor. Hold it there for a few seconds. This discharge process often results in a loud and startling ‘POP’ sound.
5. Repeat the process to create a short circuit between each capacitor terminal and the chassis (bare metal mounting plate surface). If the capacitor has three terminals, use the same method.

Troubleshooting steps

With some targeted troubleshooting, you can pinpoint the cause of the power interruption causing the F7 code. Here is a step-by-step guide:

Step 1: Unplug and reset

1. Unplug the microwave or disconnect power.
2. Leave the microwave unplugged for at least 40 seconds.
3. Reconnect the power after 40 seconds.
4. Check if the F7 error persists. If the error is still there, move on to the next step.

Step 2: Check cooling fan operation

1. Open the microwave housing to access the cooling fan.
2. Check for any obstructions around the fan.
3. Inspect the fan blades for dust buildup or visible damage.
4. Spin the fan blades manually to make sure that they can move freely.
5. If the fan does not operate when the microwave is on, or if there are any signs of damage, replace the fan.

Step 3: Test the magnetron

1. Locate the magnetron inside the microwave.
2. Look for visible damage such as burn marks or cracks on the magnetron.
3. Set a multimeter to measure ohms.
4. Place the multimeter probes on the terminals of the magnetron.
5. Check for continuity; a healthy magnetron will show low resistance (a few ohms).
6. If there is no continuity or very high resistance, replace the magnetron.

Step 4: Verify connections (P65, P56/P66)

1. Locate the P65 connector on the relay control board.
2. Check the P65 connector is firmly attached and free from corrosion.
3. Locate the P56 and P66 connectors between the relay board and inverter relay board.
4. Make sure these connectors are secure and free from damage.
5. Reconnect any loose wires.
6. Clean any corroded terminals with an electronic contact cleaner.

Step 5: Inspect wiring to the inverter  

1. Inspect all wiring leading to the inverter for signs of wear, such as frayed insulation or burnt marks.
2. Check each connection point to make sure that the wires are securely attached.
3. Replace any damaged wires.
4. Make sure all connections are tight and secure.

Step 6: Test interlock switches

1. Locate the interlock switches around the door area.
2. Set a multimeter to continuity mode.
3. Place the probes on the switch terminals.
4. Test each switch by opening and closing the door; the switch should show continuity when the door is closed.
5. If a switch does not show continuity when the door is closed, replace the faulty switch.

Step 7: Measure voltage at relay board

1. Plug the microwave back in.
2. Set a multimeter to measure AC voltage.
3. Carefully place the probes on the 4903-1 terminal on the relay board.
4. If the voltage reading is 120V, unplug the microwave.
5. This indicates a problem with the inverter or relay board.

Step 8: Replace inverter if necessary

1. Unplug the microwave.
2. Remove the inverter following the manufacturer’s instructions.
3. Install a new inverter, ensuring all connections are secure.
4. Reconnect the power and test the microwave.
5. If the F7 error persists, move on to the next step.

Step 9: Replace relay control board if problem persists

1. Unplug the microwave.
2. Remove the relay control board.
3. Install a new relay control board, ensuring all connectors are properly attached.
4. Reconnect the power and test the microwave.
5. Verify if the F7 error is resolved.

More information

Thank you for reading! We hope you found this information useful to get your microwave working again.

If you have any other appliance repair needs or projects, don’t hesitate to explore our thousands of free videos and troubleshooting guides available. If you need replacement parts or some extra help, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, order parts, read our DIY blog, and more.

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