Why does my garage door open but won't close?

Your garage door opens but won't close most commonly due to safety sensor issue, as sensors are designed to prevent closing when obstruction is detected but do not prevent opening, making this classic symptom of sensor fault. Safety sensors are small boxes near bottom of door tracks, one sending infrared beam and one receiving, with LED indicators. When sensors are misaligned, dirty, have loose wiring, or are blocked by leaves or cobwebs, receiving sensor LED blinks or goes off, and opener will open but refuse to close, often with opener light blinking 10 times or motor clicking to indicate sensor fault. To fix, clean sensor lenses with soft cloth to remove dirt and debris, ensure sensors are aligned facing each other with clear line of sight and no obstruction, and adjust by loosening wing nut and tilting until both LEDs are solid, typically sending yellow and receiving green. Check wiring for loose connections at sensors and opener unit, and ensure wires not damaged. Check for sunlight shining directly into sensor causing false blockage, and shade sensor if needed. Another cause is close travel limit set incorrectly causing door to reverse before touching floor, requiring limit adjustment via screws on opener. Door binding due to rollers off-track or broken spring can cause opener to reverse when closing because force sensor detects obstruction. Try holding wall button down continuously, which overrides sensors and forces close if sensors are issue, but fix sensors promptly for safety. Replacement sensors cost 20 to 50 dollars.