How to Test and Replace the Motor Start Capacitor on a Frigidaire Dishwasher

The motor start capacitor on a Frigidaire dishwasher provides the initial burst of energy needed to get the circulation pump motor spinning. It is a small cylindrical component (typically 4-8 microfarad, rated at 250V or higher) mounted near the circulation pump underneath the tub. When the capacitor fails, the pump motor cannot overcome its starting inertia. You will hear a humming or buzzing sound from underneath the dishwasher during the wash phase, but the spray arms will not spin because the motor is stuck trying to start.

This is a commonly misdiagnosed problem. Many homeowners (and even some technicians) replace the entire circulation pump motor when only the $15-$40 capacitor has failed. The pump motor itself is perfectly fine; it just needs the capacitor to help it start. Testing the capacitor with a multimeter takes 2 minutes and can save you the cost of an unnecessary $100-$180 pump replacement.

Before You Start

• Tools needed: Phillips #2 screwdriver, insulated screwdriver (for discharging), digital multimeter with capacitance testing (uF mode), needle-nose pliers
• Parts needed: Motor start capacitor 4-8 microfarad ($15-$40, rating must match original)
• Time required: 20-30 minutes
• Difficulty: Intermediate
• Safety warning: Capacitors store electrical energy even after power is disconnected. ALWAYS discharge the capacitor before handling by shorting across both terminals with an insulated screwdriver. A charged capacitor can deliver a painful shock. Disconnect power at the circuit breaker before starting any work.

Step-by-Step Instructions

Step 1: Confirm the Symptom Pattern

The specific symptom of a failed start capacitor is distinctive:

• The dishwasher fills with water normally (you hear the inlet valve open and water enter).
• When the wash phase begins, you hear a low-pitched humming or buzzing from underneath, but no spray arm movement.
• The humming may continue for 30-60 seconds before the motor thermal overload trips and the humming stops.
• After a cool-down period, the board may attempt to restart, producing the same hum again.
• Eventually the control board gives up and may display an error or the cycle stalls.

If instead you hear nothing during the wash phase (complete silence from the motor), the problem is more likely the motor winding itself (burned out) or the control board not sending power. If you hear normal motor operation but weak spray, the impeller is blocked or the pump seal has failed.

Step 2: Disconnect Power and Access the Capacitor

Turn off the circuit breaker. Remove the lower access panel (kick plate, 2 Phillips screws). The capacitor is typically mounted near the circulation pump motor, either clipped to the pump body, attached to a nearby bracket, or mounted to the dishwasher frame. It is a cylindrical component about 1-2 inches in diameter and 2-3 inches long, usually black or silver, with two terminal wires.

Step 3: Discharge the Capacitor

This step is critical for safety. Before touching the capacitor terminals or disconnecting wires, discharge any stored energy. Hold an insulated screwdriver by the insulated handle only. Touch the metal blade across both capacitor terminals simultaneously. You may hear a small pop or spark. This is normal. The capacitor is now discharged and safe to handle.

Step 4: Disconnect and Remove the Capacitor

Note the wire connections (photograph them). The capacitor has two terminals. Disconnect the wires by pulling the spade connectors off the terminals (use needle-nose pliers if they are tight). Release the capacitor from its mounting clip or bracket. Note the capacitance rating printed on the side (e.g., "6 uF" or "4.5 uF") and the voltage rating (e.g., "250 VAC" or "370 VAC").

Step 5: Test the Capacitor

Set your multimeter to the capacitance (uF) setting. Touch the probes to the capacitor terminals. A good capacitor should read within 10% of its rated value. For example, a 6 uF capacitor should read between 5.4 and 6.6 uF.

Failure indicators:

• Zero or very low reading (0.0-0.1 uF): Capacitor is shorted or completely failed. Replace.
• Open circuit (no reading / OL): Capacitor has opened internally. Replace.
• Reading more than 20% below rated value: Capacitor has degraded and cannot provide adequate start energy. Replace.
• Capacitor case is swollen, leaking, or cracked: Replace regardless of test results. Physical damage means the dielectric has broken down.

If your multimeter does not have a capacitance mode, you can perform a charge/discharge test: set to DC volts, briefly touch a 9V battery to the capacitor terminals (observing polarity on polarized caps), then measure voltage across the capacitor. It should read near 9V and slowly decrease. A dead capacitor will show 0V or not hold any charge.

Step 6: Purchase the Correct Replacement

The replacement capacitor must match the original in:

• Capacitance (uF): Must be the same value (4, 5, 6, or 8 uF depending on model)
• Voltage rating: Must be equal to or higher than the original (250V or 370V is common). A higher voltage rating is acceptable; lower is not.
• Physical size: Must fit the mounting clip

Frigidaire motor start capacitors are not model-specific. Any capacitor with the correct uF and voltage rating will work. They are available at appliance parts stores and electrical supply houses.

Step 7: Install the New Capacitor

Mount the new capacitor in the same clip or bracket position as the old one. Reconnect the wires to the same terminals as documented in your photo. Push the spade connectors on firmly. The capacitor connections are not polarity-sensitive on AC motor start capacitors (they are non-polarized), so either wire can go to either terminal.

Step 8: Test the Repair

Reinstall the kick plate. Restore power at the breaker. Run a Normal cycle. When the wash phase begins, listen for the pump motor starting cleanly (a brief surge sound followed by smooth running). Open the door mid-wash and verify the spray arms are spinning. The humming/buzzing symptom should be completely gone. If the motor still hums without starting, the problem may be the motor itself (seized bearings preventing rotation even with adequate start energy).

Understanding Why Start Capacitors Fail

• Age: Electrolytic capacitors degrade over time as the dielectric material dries out. After 8-12 years, the capacitance value drops below the threshold needed to start the motor.
• Heat exposure: The capacitor sits near the pump motor which generates heat. Prolonged heat accelerates dielectric breakdown.
• Power surges: Voltage spikes can puncture the capacitor dielectric, causing an immediate short.
• Frequent starts: Each start cycle stresses the capacitor. Short cycles (like canceling and restarting frequently) stress it more than normal operation.

Capacitor vs. Motor: Decision Table

When to Call a Professional

• You are not comfortable discharging a capacitor. The shock from a charged start capacitor is painful and can cause injury if you jerk your hand into nearby sharp components.
• The motor still does not start after capacitor replacement. The motor bearings may be seized, requiring full pump replacement.
• The capacitor wiring is burned or melted at the connectors, indicating a sustained short that may have damaged the control board relay.
• You cannot locate the capacitor on your specific model (some newer Frigidaire models have the capacitor integrated into the motor housing and it is not separately replaceable).

Cost Comparison: DIY vs Professional

Need Professional Help?

• Dishwasher repair service
• Frigidaire appliance repair
• Dishwasher repair cost guide

FAQ

Q: My Frigidaire dishwasher pump hums but does not wash. Is it the capacitor or the motor? A: In approximately 70% of cases where the pump hums but does not start, the start capacitor has failed. This is because the motor winding is intact (it draws power and creates the hum) but cannot overcome starting inertia without the capacitor boost. Test the capacitor first (should read within 10% of rated uF). If the capacitor tests good, then the motor bearings are likely seized (rare but possible).

Q: Can I use a higher microfarad capacitor than the original? A: It is not recommended. A significantly higher capacitance can cause excessive starting torque that stresses the motor windings. Stay within 10% of the original value. Using a higher voltage rating (e.g., 370V instead of 250V) is acceptable and actually provides a safety margin, but the uF value must match.

Q: How do I safely discharge a dishwasher motor capacitor? A: Disconnect power at the breaker. Wait 30 seconds. Hold an insulated screwdriver by the insulated handle only. Touch the metal blade simultaneously across both capacitor terminals. A small pop or spark indicates the stored charge was released. After discharge, the capacitor is safe to handle. Do not skip this step even if you think the capacitor is dead.

Q: Do all Frigidaire dishwashers have a start capacitor? A: Not all models. Newer Frigidaire models (2020+) may use an electronically commutated motor (ECM) that does not require a start capacitor. Older models with induction-type circulation pump motors typically have a separate start capacitor. Check underneath your unit: if you see a cylindrical component with 2 wires near the large pump motor, your model has one.

---

Need a certified technician? Book same-day repair →