Why Commercial Overhead Doors Close Then Reopen at the Bottom

A commercial overhead door that closes fully then immediately reopens is typically experiencing a false obstruction signal from the safety system. This is not a random fault—it’s a repeatable sequence where the door travels down, contacts the floor, triggers the bottom astragal switch, and the controller interprets that as an obstacle, commanding reversal. The issue almost always originates at the door’s lower threshold where mechanical alignment, switch function, or track geometry disrupts normal operation.

How the Close Cycle Should Work

During a normal close, the door descends under motor power until the bottom astragal seal compresses against the floor. This activates a mechanical or electrical switch mounted on the door’s bottom bar. The switch sends a signal to the controller confirming full closure. The controller then cuts power to the motor and engages the brake. If the switch fails to activate, or activates too late, the controller assumes an obstruction and reverses the door to prevent damage or entrapment.

Common Mechanical Causes of False Obstruction

Several physical issues can prevent the bottom switch from triggering at the right moment. A worn or compressed bottom astragal seal may not make sufficient contact with the floor to actuate the switch. If the door panel has sagged or the bottom bar is bent, the seal may lift off the floor on one side, creating uneven pressure. Debris like ice, gravel, or packaging straps caught under the door can also block full closure. In older systems, the switch itself may be corroded, misaligned, or have loose wiring, causing intermittent signals.

What the Failure Looks and Sounds Like

You’ll observe the door closing normally, then stopping abruptly about an inch above the floor before reversing upward. There’s often a distinct clutch slip or motor strain sound as the controller detects resistance and cuts power. The door may pause for a half-second before accelerating upward. Some systems flash an error code on the wall station or log a fault in the controller’s history. Unlike a hard stop from an actual obstruction, there’s no visible object blocking the path—just the door’s refusal to stay down.

What Facility Staff Can Safely Check

Before calling a technician, inspect the door’s path for obvious obstructions. Clear ice, dirt, or debris from the threshold and check that the bottom seal is intact and not torn or hardened. Manually lift the door to waist height and release it—it should stay put if the springs are balanced. If it drifts down, spring tension may be off, but do not adjust springs yourself. Check the bottom bar for visible bends or damage. Listen for unusual grinding during travel, which could indicate track or roller issues.

When Professional Service Is Required

If the door reverses consistently despite a clear threshold and intact seal, the problem likely lies in the switch mechanism, controller logic, or door alignment. A technician will test the switch circuit with a multimeter, verify controller input, and inspect the door’s lateral and vertical track alignment. They may shim the track, replace the astragal, or recalibrate the close force settings. Never attempt to disassemble the bottom bracket assembly or tamper with the torsion spring system—these components store lethal energy and require specific tools and training to service safely.

Frequently Asked Questions

Can a misaligned photo eye cause the door to reopen after closing?

Photo eyes prevent closing if obstructed but do not trigger reversal after the door has already closed. Once the door is fully down, the photo eye circuit is irrelevant to the close cycle. A reversing door after full closure points to the bottom switch or controller, not the photo eyes.

Does cold weather make this problem worse?

Yes. Rubber seals harden in freezing temperatures, reducing their ability to compress and activate the bottom switch. Ice buildup under the door can also block full closure. In unheated facilities, this issue appears more frequently in winter months as seal flexibility decreases.

Is adjusting the close force limit a safe fix?

Increasing close force to overcome a false obstruction signal masks the underlying problem and creates a safety hazard. The door may then fail to reverse when encountering a real person or object. Close force should only be set to the minimum needed to latch the door, not to overcome mechanical resistance from a fault.

CCGDS (604) 206-5727