How to Test Frigidaire Dishwasher Start Capacitor

The start capacitor gives the induction pump motor the jolt it needs to break away from a standstill. Without it the motor draws power and hums but cannot turn, so no water reaches the spray arms. The trap is assuming a humming pump means a dead pump; the winding is usually fine and just needs its capacitor. A meter check settles it in minutes and can save an unnecessary pump replacement.

Tools and Parts#

Before You Start#

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#

1. Match the symptom precisely#

A start-capacitor failure has a distinctive signature: the dishwasher fills normally, then at the wash phase a low hum or buzz comes from underneath with no spray-arm movement. The hum often runs half a minute before the motor's thermal overload trips it, and the board may retry and hum again before giving up. Total silence at the wash phase instead means a burned winding or no power; normal running with weak spray means a blocked impeller or failed seal.

2. Access the capacitor#

Kill power at the breaker and pull the kick plate off with its two screws. The capacitor is a small cylinder — an inch or two across and a couple of inches long — clipped to the pump body, a bracket, or the frame near the circulation motor, with two spade wires.

3. Discharge it before touching#

Hold the insulated screwdriver by its handle and bridge both terminals at once; a small pop or spark is the stored charge releasing. Do this even if you are sure the capacitor is dead — it is the one non-negotiable safety step of the job.

4. Note the rating and test#

Photograph the two wires, pull the spade connectors, and read the printed rating (its microfarad value and a voltage such as 250 VAC or 370 VAC). On capacitance mode, a good capacitor reads within about a tenth of its rating; a zero reading, an open reading, or a value far below rating condemns it, as does any swelling, leaking, or cracking. No capacitance mode? Set DC volts, briefly touch a 9V battery across the terminals, then read the capacitor — it should show near nine volts and bleed down slowly, while a dead one holds nothing.

5. Match the replacement#

The new capacitor must match the microfarad value exactly, since too much overdrives the winding and too little will not start the motor. Its voltage rating must equal or exceed the original, so stepping a 250-volt part up to 370 volts is fine but never down. These are non-polarized, so either wire goes on either terminal.

6. Install and test#

Clip the new capacitor into the old position, push the spade connectors firmly onto the terminals per your photo, and refit the kick plate. Restore power, run a Normal cycle, and listen at the wash phase for a clean start followed by steady running with the spray arms turning. If the motor still only hums, the pump bearings are likely seized.

Capacitor or Motor?#

Why Start Capacitors Fail#

• Age dries out the dielectric, so after many years the value drifts below what the motor needs to start.
• Heat from the nearby motor speeds that breakdown.
• A voltage surge can punch through the dielectric and short it instantly.
• Frequent stop-start cycles stress it more than steady running does.

When to Call a Pro#

Call a technician if discharging a capacitor is outside your comfort, if the motor still will not start after a new capacitor (seized bearings mean a pump replacement), if the wiring is burnt at the terminals, or if your newer Frigidaire uses an electronically commutated motor with no separate capacitor to service.

Need Professional Help?#

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