Ductless mini-splits are common in Tiburon, Belvedere and Mill Valley homes that have no ducts, radiant floors, or an addition the central system never reached. When one stops heating or cooling, the cause is usually on a short list: dirty filters or a clogged blower wheel, a blocked condensate drain, a failed temperature sensor, a fan motor, a refrigerant leak at a flare joint, or a fault in the communication between the indoor and outdoor units. Telling them apart takes more than reading the code.
How a mini-split repair works
- Read the code. Each brand reports faults differently: blinking lights on the indoor unit, a code on the remote, or a display on the outdoor board. We note the code and the unit’s history before touching anything.
- Test the circuit it points to. A sensor fault is confirmed by measuring the sensor; a communication fault by checking the voltage and wiring between the units; a compressor or inverter fault by measuring at the outdoor board.
- Check the basics anyway. Filters, blower wheel, coil, drain and refrigerant pressures, because one problem often hides another.
- Quote. You get an upfront price and, if a board or sensor has to be ordered, the expected timeline. Inverter boards and sensors are often specific to one model, so parts availability is part of the conversation.
- Repair and test. The unit is run in heating and cooling, and we confirm the code has cleared.
Leak repairs and recharging are handled by our EPA-certified technicians.
Common problems
| What you notice | Likely cause | What it usually takes |
|---|---|---|
| Blinking lights, unit won’t start | Sensor, communication wiring or board fault | Testing the circuit the code names |
| Water dripping from the indoor head | Blocked drain, failed condensate pump, frozen coil | Drain clearing, pump replacement, airflow fix |
| Weak airflow, musty smell | Dirty filters and blower wheel, growth on the coil | Deep cleaning of the indoor unit |
| Runs but barely heats or cools | Low charge from a leak, often at a flare joint | Leak repair, evacuation and recharge |
| One head works, another doesn’t | Sensor, valve or wiring for that zone | Zone-by-zone testing |
| Outdoor unit silent | Power, fuse, fan motor or inverter board | Electrical diagnosis at the outdoor unit |
Before you call
- Check the remote: the right mode (Heat, Cool, Dry or Auto), a sensible setting and fresh batteries.
- Lift the front panel and look at the filters. If they are grey, rinse them and let them dry before refitting.
- Make sure the breaker or outdoor disconnect has not tripped.
- Write down the blinking pattern or the code on the display.
- Clear leaves and branches away from the outdoor unit.
If the indoor unit is leaking onto a wall or floor, switch it off at the remote and keep it off until the drain is checked.
Repair or replace?
Most mini-split faults come down to a single part and are worth repairing. Replacement becomes a real option when the compressor fails on an older system, when the leak is in a coil rather than a joint, or when boards for the model are no longer available. If you are adding rooms or retiring an older system, see mini-split installation.
Brands and local notes
We work on Mitsubishi, Fujitsu, Daikin, LG and Samsung systems, among others. Near the water in Tiburon and Belvedere, salt air corrodes outdoor coils and the flare connections at the outdoor unit, a frequent leak point. In Mill Valley’s shaded, damp homes, indoor heads run in heating mode for much of the year, and their blower wheels and coils collect dust and mold faster than owners expect. See the local pages for mini-split repair in Mill Valley, Tiburon and Belvedere. Ducted heat pumps with similar symptoms are covered under heat pump repair.