Ductless mini-split annual maintenance checklist

Lock and tag applied before any head cover comes off

Each circuit feeding the outdoor unit and heads locked and proven dead; heads closed up, the charge check run under the procedure's temporary release (locks off by their owner), then re-locked.

Wash bag and floor cover rigged under the head

Room occupant told first, coil cleaning bag fitted to drain into a bucket, wall and floor below covered, and electronics in the head shielded from the rinse water.

Blower wheel and indoor coil cleaned

Head opened, blower wheel and coil cleaned of biofilm and dust, a cleaning that restores airflow rather than just swapping the filter.

Condensate line flushed clear

Full drain line flushed and confirmed flowing, pump reservoir and float cleaned, trap or check verified where fitted.

System charge and operation checked against the data plate

Operating pressures and temperatures read where the system allows, compared against the manufacturer's charging data, a low reading treated as a leak to find rather than a top-off.

Line-set connections and insulation inspected

Flare and connection points checked for oil residue that signals a leak, insulation resealed at the wall penetration and any exposed run.

Flare joints tested with a detector at each head

Beyond the look for oil, flare nuts behind each head and at the outdoor service valves tested with an electronic detector or bubble solution.

Flare repairs and charge changes handed to a certified tech

Flare remakes, recovery and any charge weighed in done by a certified refrigerant technician, noting which head's line set was worked on and the refrigerant used in the system log.

Electrical connections and disconnect checked

Whip and terminal connections tight at the outdoor unit, disconnect intact, no heat discoloration at the lugs.

Interconnect terminals checked inside each head

With the circuits re-locked and proven dead, power and communication wires tight at the head's terminal block, no heat marks, chafing or water tracking along the cable.

Mounting, brackets and clearances verified

Wall bracket and outdoor pad or stand secure, head level so the pan drains, clearances around the condenser maintained.

Covers refitted, locks cleared and system restarted

Head covers, filters and front panels back on, locks removed by the person who hung them, and each head run in heat and cool until it settles.

Supply and return temperatures measured at each head

Thermometer readings at the return and supply of every head in cooling, the split compared with last year's so a head losing capacity stands out.

Annual readings logged by head for next year

Temperature splits, charge readings, cleaning notes and any leak found entered against each head so next year's service starts from this one.