If a garage door opener sits idle for a period of time a blown starting capacitor can build up and store enough energy to run the opener a few cycles.
Garage door capacitor symptoms.
My garage door opener stopped working but it isn t a drive gear problem.
After running a few cycles the opener will usually stop running and make a humming or clicking sound.
When the capacitor isn t working in your garage door opener the symptom is usually humming or buzzing without any motion of the door when you press the start button.
Replying to toller matt wrote.
Take safety precautions as usual and follow some pretty fast and easy directions below and you should have no problem getting a reading on your garage door opener capacitor.
The first thing you will want to do before hooking up your voltmeter is to take a look at your capacitor.
Step 1 visual problems first.