We have two Liftmaster Slide Open gates at my work which have been having issues for the last few months. The main control board appears to me to be the LiftMaster Main Control Board (DC Pad-Mount, UL325) | LIF-K1D8389-1CCMC.
We will call the first gate the East Gate, and the second gate the West Gate. The East gate is opened with a hold open code at the keypad in the morning. It forces the trucks to enter the East gate. The West gate is always closed and opens via the ground loop when the trucks drive up to the gate.
For the last few months the East gate will not close with the code. We've had a gate technician out probably 7 or 8 times. He told me initially that the control board was giving 3 codes that typically are not given which signified a dead or fried board. We paid to replace the board, it fixed the issues for a few weeks and then they started up again. He came back out and checked it out, called Liftmaster and they said the board was giving an undervoltage code. There are two motors per entrance, and each motor has it's own dedicated 120v 20amp power.
The Tech showed me how to reset the board by pulling the Safety Eye wires and the Wireless edge, Push the Set Open/Set Close buttons together, the other side of the gate sounds an alarm, after that alarm I press both Set Open/Set Close buttons again, wait a little and plug the eye and wireless edge sensors back in. The gate will then close by code again and sometimes will function for a week, sometimes will function for a day before I need to do the whole process again. The tech seems dumbfounded by the issue and says he's never seen this before.
I've been trying to understand what is happening on the days that the issue arises. My first thought is that we received 4 brand new cherry picker forklifts and installed 4 new chargers. However these charges replaced older forklift chargers and appear to be more efficient. They are also 480v and only pull 4 amps each. The 120v panel that powers the gate is fed by the 480v panel through a transformer. I'm told that because there is a transformer between the panels that a surge will not affect the 120v panel. I also installed Ditek Inline Surge Protectors for each leg feeding the motors. Not sure if this worked or did anything, but the gates functioned for a week before having issues again.
Another thing I thought about is the heat wave we've been having this summer. We are located in southern California and it has been hotter than normal. The problem does seem to happen on the hottest days (motor/control board housing is in direct sun most of the day), but yesterday was a relatively cool day and the gate needed to be reset again. So I'm not sure if heat is the cause of the issue.
I mentioned the West gate earlier, that gate just recently started to not close behind exiting trucks, however, after resetting it will function for several weeks. I've had to maybe reset that gate 3 times in the last two months where the West gate needs to be reset about every other day. The West gate is powered by a completely different 120v panel.
I'm at my wits end, and don't want to throw another $1,500 per gate to replace the control board if that didn't work before. I'm reaching out to the knowledgeable people of Reddit to see if anyone has any experience or troubleshooting tips to figure out this issue.