When raising a power window, what happens when the window reaches the top of the opening? These "universal" actuators have no fancy limit switch circuitry, so what does the motor do when it can't push the window up any further?

 

I don't know how, but mine just stop. There must be something that stops the motor, maybe it is magic. I got mine from Specialty Power Windows and they work great, bolted right up into the original screw holes for the window roll up hardware.

 

I had the same question when I did mine, wondered if I needed to add micro limit switches. I called the manufacturer, who said they were not required. Don't remember now what his explanation was, but it made sense to me at the time, and they work just fine too....

 

I am almost positive they have a clutch set up like factory.

 

Clutch sounds reasonable although I wonder why the actuator doesn't chatter when the clutch engages...ala power drill clutch? The power window actuator that I am using has a longer travel than the height of the window glass. Assuming the clutch kicks in at the top, I am going to assume that I can place a stop on the track to keep the glass from dropping too far into the door and that the clutch will activate again on the downward path. I have a couple of spare window motors laying around here someplace, maybe I'll just take on apart and see what "magic" lies within.

 

I believe its the same as some servo motors, once the motor has recieved a drop in movement it triggers off. Basically the window will roll up until closed all the way, then the motor will shut off. Its not a powerful motor and normally they have internal saftey switches.

 

I'm curious which kit you used? I'm needing one for my '53 C500. Thanks, Ken.

 

Most just have an internal circuit breaker (self-resetting.) The motor is made to stall for quite a while without damage but if it begins to overheat the breaker will kick out. It's normally not an issue as most peeps will get bored with holding the button before the motor overheats. ;-)