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Brian, Architect
Category: Home Improvement
Satisfied Customers: 3123
Experience:  Licensed Architect- 17 years, L.E.E.D. AP
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About two weeks ago my garage door was open and I attempted

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About two weeks ago my garage door was open and I attempted to close it. It traveled about 18" and went back up. I attempted to close it a couple more times and even continually held the button down, but it did the same thing. I checked the sensors and there was no obstruction. The one green light was very dim, so I adjusted the sensors a little and pushed the button and the door closed. I cycled through open and close three times and it worked fine.
After about two days it did the same thing, so I ordered a new set of sensors from Sears. I installed and adjusted them and it worked fine for another two days. Then it did the same thing. Both sensor lights are on bright. I wiggled and adjusted both of them a little and the door worked fine again for another day. That brings me to last evening when the door wouldn't close again. As I said it travels about 18" and then reverses and goes up all the way. I checked the wiring from the sensors to the opener and everything looks fine. The connections at the opener are tight. Anyone have any ideas out there?
Hi, my name is XXXXX XXXXX I will be helping you today.

If the sensors and wiring are good and they are aligned then most likely the RPM sensor is defective and needs to be replaced or you disrupted it if you recently replaced anything inside the motor unit. Let me know if you recently replaced anything and if you didn't, proceed with the following information.

The RPM sensor is a little circuit board located at the door end of the motor shaft, inside the motor unit. They are relatively easy to purchase and install.

The RPM sensor is what causes the door to reverse when it hits something. When the door hits something the logic board doesn't receive the pulses sent by the sensor and it reverses. When this sensor goes bad the door will start down (or up) and the logic board will not receive the electronic pulses and it will reverse, just like yours is doing.

Take the cover off the unit and you will see a black cap on the end of the shaft that rotates between infrared sensors. That small circuit board is the RPM sensor.

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Customer: replied 4 years ago.
Nothing inside the motor unit has been replaced, so it's probably the RPM sensor as you said. I will open up the unit when I get home this evening and see if I can find it. If so, I'll try to order one and install it. I'll let you know.

Great, good luck with it Gary.
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