Mini-splits are reliable, but when one stops cooling the causes are different from a ducted system. There is no shared duct network, no big filter cabinet, and each head is its own small system with its own failure points.
Blowing warm air
Start with the obvious: confirm the remote is in cool mode with a setpoint below room temperature, and that no one has left it in fan or dry mode. After that, the usual causes are dirty head filters, a blocked outdoor unit, a refrigerant leak at a flare connection, or a failed outdoor fan or capacitor. Flare joints are the classic mini-split leak point, especially on installs that were not torqued to spec.
Water dripping from the indoor head
Mini-splits drain by gravity through a small condensate line. A clogged line, a sagging drain hose, or a head mounted slightly out of level all send water down the wall instead of outside. It is a common failure and usually straightforward to correct — but ignore it and you get drywall and framing damage.
Blinking lights and error codes
Each manufacturer uses its own code set, and the blink pattern on the indoor head points directly at the fault: sensor, communication, high pressure, or inverter board. Note the pattern before you power cycle the unit; it saves diagnostic time.
One head works, another does not
On a multi-zone system that points at the individual head, its line set, or the branch controller — not the outdoor unit. If every head is out, the problem is upstream at the condenser or the power supply.
What a mini-split repair visit covers
- Mode, setpoint and error code confirmed at each head
- Filters and blower wheel inspected and cleaned
- Condensate path checked and cleared
- Refrigerant charge and flare connections checked for leaks
- Inverter board, sensors and communication wiring tested
- Outdoor unit coil, fan and electrical components checked
- Written estimate before any repair work begins
Related reading
Our ductless mini-split page covers repair, installation and maintenance in more detail. If the problem is with a conventional ducted system instead, see our AC repair page.
Frequently asked questions
Why is my mini-split blowing warm air?+
Common causes are a wrong mode setting, dirty head filters, a blocked outdoor unit, a flare-connection refrigerant leak, or a failed outdoor fan or capacitor.
Why is water dripping from the indoor unit?+
Almost always a clogged or sagging condensate drain, or a head that is not level. It needs attention before it damages the wall.
Do mini-splits need maintenance?+
Yes — head filters and blower wheels need regular cleaning, and the condensate path and refrigerant charge should be checked annually.
One room is not cooling but the others are. Why?+
On a multi-zone system that isolates the fault to that head, its line set or the branch controller rather than the outdoor unit.
Can a mini-split heat as well as cool?+
Most systems sold today are heat pumps, so yes — the same head heats the room in winter.
Related posts
September 8, 2026 · 6 min read
Heat Pump Not Heating? A Sacramento Repair Guide
Cold air in heat mode, ice on the outdoor unit, constant running — what each heat pump symptom actually points to.
Continue reading Heat Pump Not Heating? A Sacramento Repair GuideSeptember 4, 2026 · 5 min read
What an AC Tune-Up Actually Covers in Sacramento
Maintenance quotes vary because scope varies. Here is exactly what should be measured on a Sacramento AC tune-up.
Continue reading What an AC Tune-Up Actually Covers in Sacramento