door opener just clicks once when i press the button, nothing moves

Diagnosis

The single "click" you hear is the sound of the logic board's relay engaging, which confirms that the wall button, remote, and control board are receiving power and communicating correctly. However, the motor fails to turn because it lacks the necessary electrical "kick" to overcome static friction and move the heavy garage door. In the Craftsman 54930, this is almost always caused by a failed start capacitor. The start capacitor acts like a temporary battery that provides a high-voltage burst to the motor windings to initiate rotation. Over time, the electrolytic fluid inside the capacitor dries out or the internal foil degrades, leading to a loss of capacitance. You can confirm this by observing the motor: if you hear the relay click and perhaps a very faint hum for a split second before silence, the capacitor is dead. Visually, you may see a "bulged" top or a brownish leak emanating from the bottom of the cylindrical component on the board.

How to Fix It

To resolve this, you must replace the failed capacitor with one matching the exact microfarad (µF) and voltage ratings.

1. Disconnect the opener from the 120V AC power outlet. This is critical as capacitors can hold a lethal charge even after the power is off.
2. Remove the plastic motor housing cover by unscrewing the side panels and sliding the shroud backward.
3. Locate the start capacitor on the logic board. It is a small, cylindrical component. Note the specifications printed on the side (e.g., 12µF 125VAC).
4. Using a multimeter with a capacitance setting, place the probes on the capacitor terminals. If the reading is significantly lower than the rated µF or reads "OL" (Open Loop), the part is defective.
5. Desolder the old capacitor from the logic board using a soldering iron and a solder sucker/wick. Be careful not to overheat the board traces.
6. Insert the new capacitor, ensuring the polarity is correct if it is a polarized model. Solder the connections firmly and use heat-shrink tubing to prevent any short circuits against the chassis.
7. Reassemble the housing, plug in the unit, and test the operation.

If That Didn't Work

• Check the Motor Thermal Overload: If the opener was used frequently just before it failed, the internal thermal overload protector may have tripped. This is a safety switch that cuts power to prevent the motor from burning out. Unplug the unit for at least 30 minutes to allow the bimetallic strip to cool and reset, then try again.
• Inspect the Drive Chain Tension: A chain that is too tight puts excessive load on the motor, preventing it from starting even with a good capacitor. Check the tension of the chain; it should have a slight sag of about 1/4 to 1/2 inch in the middle. If it is tight as a guitar string, loosen the adjustment nuts on the carriage.
• Test the Door Balance: Disengage the emergency release cord (the red handle) and try to lift the door manually. If the door is heavy or sticks, the motor is simply stalling under the load. If the door doesn't stay open halfway on its own, your torsion springs are worn out and need professional replacement.
• Verify Logic Board Relay Continuity: Use your multimeter to check if the relay is actually sending voltage to the motor. If the relay clicks but no voltage reaches the motor terminals, the relay contacts inside the logic board may be charred or pitted, requiring a full replacement of the logic board.

Heads Up

• Capacitor Safety: Always discharge a capacitor before touching the terminals by bridging them with a resistor or an insulated screwdriver to avoid a severe electric shock.
• Avoid Cheap Generic Parts: Use high-temperature rated capacitors. Cheap replacements often fail within months because the interior of the motor housing reaches temperatures that cause low-grade capacitors to leak.
• Chain Lubrication: Lubricate the drive chain every six months with a white lithium grease. A dry chain increases the amperage draw on the start capacitor, shortening its lifespan.
• Voltage Spikes: If you live in an area with frequent power surges, consider plugging your opener into a high-quality surge protector to prevent the logic board's sensitive components from frying.