I'm working on a 4-stop, hydraulic wheel-o-vator destiney model.

If left on the highest floor on a hot day, trying to descend results in the cab lowering just 6 inches, stopping, then returning to the top floor. Calling the elevator down without any load gives the same results. Resetting the PLC doesn't help. The magnets appear to still be properly placed. With the heat wave subsided, it started working again.

Has anyone seen this problem or have a suggestion?

Why would the heat have anything to do with it? And why do you say without a load? Does it travel down with a load?

I mentioned heat because it was significantly hotter here in RI when it failed to work. When I resumed troubleshooting and found it was working again, the only difference I noted was much cooler air temperature. Nothing else changed.

By without a load, I meant with an empty cab - no people or objects that might trip an overload circuit. When the problem was happening, it would not travel down more than the 6 inches with or without a load.

Thanks for your interest.

It sounds like one of the sensors in your selector is being affected by the heat. I had a similar issue on a Destiny and it was the DZ sensor.

All electrical components that are csa approved should be more than capable to operate properly during any heat wave. The outside ambient temperature has crap to do with a sensor not functioning. I doubt it is 100º+ in the hoistway or machine room, and if it is, buy air conditioning for it. Now if this home lift has some type of tape selector with magnets... they could possibly come "ungled." But that's very doubtful since it started working again normally without making any adjustments or repair. If it moved at all (6") you can be assured the safety circuit was good. I'd be checking that upper floor door lock since the lock cam was probably opening it at the 6" point. Good luck.

Thanks for the helpful advice. I'll do another close inspection, but otherwise wait for it to stop working again and troubleshoot.

Tom,
Try a heat gun or hair dryer!

I would check out the door locked circuit really well......I'm willing to bet that's where the problem is. What kind of locks are on this thing?