Repair guides
Pick a type, an appliance or a brand. Every guide lists the tools, the safety call-outs, the steps and the reading you should expect.
Diagnostic · 374
Symptom → most likely cause, step by step
Component tests · 69
How to test a specific part, with expected readings
Installation · 33
Install, replace and hook up appliances correctly
Fundamentals · 24
Core skills every appliance tech uses
Appliance
Brand-specific guides
12 guides · Garage Door Openers
Diagnostic · 12
Guide · Garage Door OpenerDoor stops short or reverses at the floor (travel limits and force)
Usually travel limits or force need reprogramming, or the door is binding/out of balance. Test the door by hand first.
Guide · Garage Door OpenerGarage door reverses or will not close (safety sensors)
Nearly always the photo-eye safety sensors: blocked, misaligned, sun-blinded or miswired. Sensors must be repaired, never bypassed. If sensors are fine, look at force/limits and door binding.
Guide · Garage Door OpenerGarage door won't move with the opener after the red release cord was pulled
The emergency release disconnects the door arm from the trolley. Re-engaging it is usually a matter of setting the release back to its connected position and running the opener so the trolley catches the carriage. First confirm the door is balanced; a heavy door means a spring problem, which is blocked work.
Guide · Garage Door OpenerGarage opener light stays on, or will not light
A light that stays on is usually a feature (light button, motion detection, safety-light on beam break) or a door control/wiring fault; Chamberlain gives a test that separates the door control from the logic board. A dead light is usually the bulb, its type, or the socket.
Guide · Garage Door OpenermyQ Wi-Fi opener offline or will not connect
myQ openers join only 2.4 GHz networks. Read the Wi-Fi LED, power-cycle opener and router, clear Wi-Fi and rerun setup in the app.
Guide · Garage Door OpenerNoisy garage door opener
Loose fasteners, poor lubrication, slack chain, worn drive gear or an unbalanced door. Separate opener noise from door noise by running each alone.
Guide · Garage Door OpenerOpener beeping (battery backup)
Beeps come from the battery backup: running on battery, low battery or a worn-out battery. Replace the 12 V battery when the LED is solid red.
Guide · Garage Door OpenerOpener light or LED blinking
Blinks are diagnostic. Count the pattern and look it up by brand: LiftMaster arrows/Learn LED, Genie powerhead LED, Overhead Door round/long LED.
Guide · Garage Door OpenerOpener runs or hums but the door does not move
Separate a disconnected trolley, a stripped gear/sprocket, a jammed trolley or a door problem (lock, broken spring). Door-side spring problems go to a door technician.
Guide · Garage Door OpenerOpener strains or door won't lift: broken spring (diagnose and refer)
Springs carry the door weight; the opener only guides it. A broken torsion or extension spring makes the door too heavy, and the opener strains, reverses or strips gears. Spring and cable work is blocked: confirm the symptom safely and refer to a garage-door technician.
Guide · Garage Door OpenerRemote or keypad will not operate the opener
Check lock/vacation mode first, then the remote battery, then reprogram using the Learn/SET button. Short range is often radio interference from nearby LED bulbs.
Guide · Garage Door OpenerWall button not working (or door opens by itself)
A shorted or reversed wall-control wire is the usual cause, often from a staple. Phantom operation is commonly a shorted wall button or a stuck remote.