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

Older KitchenAid dishwashers (pre-2016 models, particularly KUDS, KUDL, and early KDTE series) use a motor start capacitor to provide the initial electrical boost needed to start the circulation pump motor spinning. When this capacitor fails, the motor hums or buzzes during the wash phase but cannot start rotating. You may hear a brief hum followed by a click (the overload protector tripping), then silence, then the hum-click pattern repeating.

Newer KitchenAid models (2016 and later) use electronically-commutated motors (ECM) that do not require start capacitors. If your dishwasher is from 2016 or newer, a no-start condition is more likely a motor or control board failure rather than a capacitor.

Before You Start

• Tools needed: 1/4" hex nut driver (kick plate), multimeter with capacitance testing mode, insulated screwdriver (for discharge), needle-nose pliers, Phillips screwdriver
• Parts needed: Motor start capacitor (~$15-$35). Match capacitance rating (microfarads) and voltage exactly
• Time required: 25-40 minutes
• Difficulty: Intermediate to Advanced
• Safety warning: CRITICAL: Capacitors store electrical energy even after power is disconnected. You MUST discharge the capacitor before handling it. Failure to discharge can result in painful electric shock. See Step 5 for safe discharge procedure. Disconnect power at the circuit breaker before beginning any work.

Does Your Model Have a Start Capacitor?

• Models WITH start capacitor: KUDS, KUDL series, early KDTE (pre-2016). These have single-phase induction motors that need a capacitive boost to start
• Models WITHOUT start capacitor: KDTE/KDTM/KDFE from 2016 onward. These use ECM motors with built-in electronic start circuits

To check: remove the kick plate and look for a small cylindrical or oval black plastic component (about the size of a C-battery) mounted near the circulation pump motor or attached to the frame. It will have two wires connecting to the motor circuit.

Symptoms of Capacitor Failure

• Motor hums during wash phase but does not spin (no spray arm rotation, no water splashing)
• Repeated hum-click-silence pattern (motor tries to start, overload trips, resets, tries again)
• Cycle starts normally (fill phase works) but fails when wash phase begins
• Burning smell from underneath (overheating motor winding as it stalls)
• Breaker trips after several minutes of the hum-click cycle

Step-by-Step Instructions

Step 1: Disconnect Power

Turn off the circuit breaker for the dishwasher. Verify no display lights are on. Wait 60 seconds before proceeding.

Step 2: Remove the Kick Plate

Remove the two 1/4" hex screws at the lower front. Pull the panel forward and down.

Step 3: Locate the Capacitor

The start capacitor is a cylindrical or oval plastic component (black or brown) typically mounted to the dishwasher frame near the circulation pump motor using a metal bracket and screw. It has two wires connecting to the motor start circuit. On some models, it is mounted directly on the motor housing.

Step 4: Identify the Capacitor Specifications

Before disconnecting, note the markings on the capacitor body:

• Capacitance: Measured in microfarads (uF or MFD). Common values: 10-30 MFD
• Voltage rating: Must match or exceed original (typically 250V or 370V AC)
• Both values must be matched in the replacement. Using wrong capacitance = motor won't start properly or overheats

Step 5: SAFELY Discharge the Capacitor

This step is CRITICAL for safety. Even with power off, the capacitor may hold a charge.

1. Place an insulated screwdriver (rubber or plastic handle) across the two terminals simultaneously
2. You may see/hear a small spark. This is the stored energy discharging safely through the screwdriver blade
3. Hold for 2-3 seconds to ensure complete discharge
4. Alternatively, use a resistor (20K ohm, 5W) across the terminals for a gentler discharge
5. Verify discharge by measuring DC voltage across terminals with multimeter. Should read 0V

Step 6: Disconnect and Remove the Capacitor

With the capacitor safely discharged, pull the wire connectors off the terminals (use needle-nose pliers for spade connectors). Remove the mounting bracket screw holding the capacitor to the frame. Slide the capacitor out of its bracket.

Step 7: Test the Old Capacitor

Using a multimeter with capacitance mode (often marked with a capacitor symbol):

1. Set meter to capacitance mode
2. Touch probes to the two capacitor terminals
3. Reading should be within 10% of the marked value (e.g., 15 MFD capacitor should read 13.5-16.5)
4. If the reading is 0, very low (under 50% of rated), or OL: capacitor has failed
5. If your meter does not have capacitance mode: a failed capacitor often shows as either completely open (no reading) or shorted (zero ohms) on a resistance test

Step 8: Install the New Capacitor

Mount the new capacitor in the same bracket location. Secure with the mounting screw. Connect the two wires to the terminals. The capacitor is non-polarized on motor-start types, so either wire goes to either terminal.

Step 9: Test the Repair

Restore power at the breaker. Start a cycle. After the fill phase completes (water stops flowing in), the circulation pump should start immediately with a smooth motor spin-up rather than the previous hum-click pattern. The spray arms should begin rotating within 5 seconds of the wash phase starting.

Troubleshooting After Replacement

• If the motor still hums and does not start with a new capacitor, the motor itself may have failed (seized bearings, shorted winding). Test motor resistance: 3-10 ohms normal
• If the new capacitor gets hot during operation, the capacitance value may be wrong for your motor. Verify it matches exactly
• If the motor starts but sounds rough (grinding, squealing), the bearings are worn. The capacitor got you running temporarily, but the motor needs replacement
• If the overload protector continues clicking even with a new capacitor and the motor tests good, the overload protector itself may be failed

Start Capacitor vs. Run Capacitor

Some older KitchenAid models use both:

• Start capacitor: High capacitance (100+ MFD), energized only during startup via a relay, gives the motor an initial torque boost. Fails more commonly
• Run capacitor: Lower capacitance (5-30 MFD), energized continuously while motor runs, maintains efficiency and proper phase angle. Less common failure

Most KitchenAid dishwashers use only a start capacitor. If your model has both, test each independently.

When to Call a Professional

• If you are not comfortable working with components that store electrical charge
• If the motor does not start even with a confirmed-good new capacitor (motor replacement is more involved)
• If you smell burning from the motor area (potential fire hazard if motor winding has shorted)
• If your model number indicates 2016 or newer (ECM motor; no capacitor present, different failure mode)

Cost Comparison: DIY vs Professional

Need Professional Help?

• dishwasher repair service
• kitchenaid appliance repair
• dishwasher repair cost guide

FAQ

Q: How do I know if my KitchenAid dishwasher has a motor start capacitor? A: Pre-2016 models (KUDS, KUDL, early KDTE) have them. Remove the kick plate and look for a cylindrical black/brown component mounted near the motor with two wires. Newer models (2016+) use electronically-commutated motors without external capacitors.

Q: Can a bad capacitor damage my KitchenAid dishwasher motor? A: Yes. When the capacitor fails, the motor stalls and draws locked-rotor current, which overheats the windings. Each hum-click cycle damages the motor slightly. Replace the capacitor promptly once symptoms appear to avoid motor damage.

Q: Why does my KitchenAid dishwasher hum but not wash? A: The hum-but-no-wash pattern on older models is almost always the start capacitor. The motor receives power (hum) but cannot generate starting torque without the capacitor's phase-shifted current. The overload protector trips (click) to prevent overheating, then resets and the cycle repeats.

Q: Where can I buy a replacement start capacitor for my KitchenAid dishwasher? A: Appliance parts suppliers carry exact replacements by model number. Alternatively, match the capacitance (MFD) and voltage rating and purchase from any electrical supply. The capacitor does not need to be brand-specific; it is a standard electrical component.

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