Here’s a puzzling scenario on a Samsung refrigerator: the ice dispenser door keeps opening and closing nonstop.

When you encounter a weird problem like this, it’s easy to lose your head and just start throwing parts at the machine and hoping one of them will fix it. But it’s always important to keep our fundamental troubleshooting principles firmly in mind. In this particular case, troubleshooting is made even more difficult by Samsung providing us with a very low-resolution schematic — but we can power through even that! Here’s how you would begin troubleshooting this situation.

If the ice chute door is moving without any input from the customer, that means that the control is for some reason choosing to run the ice door motor. Instead of just throwing up our hands and declaring it a bad board, let’s think about how boards operate. A control board has an algorithm that makes decisions based on inputs, so maybe we have an input that the control board is reacting to.

Samsung is often kind enough to include a pinout in their docs, and here’s the one for our particular case. They’ve gone through and labelled the purpose of each pin on each control board connector — very handy. Let’s look through those pins for something that seems related to our scenario.

See those two pins on CN90 that I’ve circled? Those are both pins that go to the two position switches for the ice chute door. The control board monitors the state of those switches by sending a small 5 VDC signal to them. If it senses that signal at CN90 pin 1 or 2, it can tell that that switch is closed. Simple as that.

If one of those switches is stuck open or closed, that could be the input that’s confusing the control board. We can easily test this by measuring for that small DC voltage at CN90 pins 1 and 2 — with respect to DC ground, of course, which we can find conveniently on the same connector at pin 8.

We can confirm what the pinout is telling us by looking at the schematic:

You see what I mean when I say that this schematic is almost unreadable — good thing we at least have the pinout to help us. Since the ice door is constantly opening and closing, we expect to see 5 VDC appearing and disappearing regularly on pins 1 and 2 as the door changes positions. That is, if they’re operating within spec. If you get nothing on one or both of those switches, then you’ve identified the bad input to the board.

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