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Light commercial HVAC

Can anyone assist after a power outage affecting all units in the building, as shown below? The green…

Discussion · Sep 8, 2026

Can anyone assist after a power outage affecting all units in the building, as shown below? The green light continuously blinks. After resetting the power, it starts up for 2-3 minutes with a solid green light and runtime, then shuts down and begins blinking again nonstop.
Field photo
Photo 1 · Field photo

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Reply · Sep 9, 2026

Please include model and serial numbers with such requests. I'm a Mitsubishi DSG. Go to the outdoor unit. Check for a fault code on the board. Check the S2 to S3 voltage on the connection going to the indoor unit. It will be either jumping around(that's good), 24VDC, or less than a volt. If 24VDC, the problem is either an open wire going inside or a bad board inside. If less than a volt, disconnect S3 wire from the terminal and recheck S2 and S3 on the screw terminals. If now 24VDC, likely bad indoor board. if still no voltage, the outdoor board is bad, IF the bus voltage, 300VDC, is on the PINK connector to the PC control board. From this point you really should be helping yourself by looking up the service manual for the model on www.mylinkdrive.com, for R410 units or if R454B, www.mitsubishipro.com. Many R410 units are on there too, but not all, yet.