Stuck for two days on a door zone fault that was just a bad limit switch

Got a call for a hotel downtown where the elevator kept stopping about six inches high. The controller kept throwing a door zone fault. I checked the sills, the hanger rollers, the whole door operator assembly. Spent maybe 16 hours over two days on it, tracing wires and checking voltages. Finally, on a hunch, I swapped the up limit switch on the car top. The old one was just worn out and sending a weak signal. Has anyone else had a simple part failure mimic a bigger system problem like that?

2 comments

2 Comments

fox.jesse2mo ago

Man, you ever just carry a spare limit switch in your kit now? I got burned by a bad down limit doing the same thing last year. It would pass a basic continuity check but fail under load. Took me forever to figure out it was a voltage drop issue. Those weak signals drive the controller nuts.

blair_green862mo ago

Carrying a spare seems like overkill to me. A proper load test with a meter would catch that voltage drop issue before it causes trouble. I'd rather spend time on solid testing than packing extra parts.