Working with Fujitsu Minisplits you may run into a time when you have no power at the indoor unit. Here are the steps to work through.

1. Check Incoming Power: Measure voltage across L1 and L2 at the outdoor disconnect/terminal block. You should read 187–253 VAC.

• Note: If voltage is outside this range, address line power issues and consider installing a Line Voltage Monitor to protect electronic boards.

2.Check Outdoor-to-Indoor Voltage: Measure voltage across terminals 1 and 2 at the outdoor unit:

• Power present at outdoor 1 & 2, but missing at indoor 1 & 2: Inspect the interconnecting field wiring for breaks, loose connections, or splices.

• No power at outdoor 1 & 2: Proceed to inspect the outdoor board fuses.

3. Inspect the Power Filter Board / Section: Disconnect power to the unit. Locate the fuse(s) on the dedicated power filter board or the power filter section of the main PCB (see photos below).

4. Test Fuse Continuity: Use a multimeter set to resistance/continuity to test the fuse(s). An open (infinite resistance / OL) reading indicates a blown fuse caused by a downstream short or power surge.

5. Isolate the Short: Use a resettable fuse tool (e.g., Lil' Popper) across the fuse holder to trace and isolate the shorted component (e.g., failed indoor PCB, fan motor, or wiring harness) without blowing replacement fuses. Using this as a tool prevents multiple board changes, saving time and money until you find the issue.

6. Finally replace the board that has the blown fuse on it and restore unit back to normal operating condition.