Mini-splits in Daly City run as heat pumps for much of the year, so a breakdown is as likely on a cold January evening as on a warm fall afternoon. Repair covers the indoor heads, the outdoor unit and the refrigerant lines between them, and most problems fall into five groups: refrigerant leaks in the line set, indoor blower motor failures, outdoor compressor problems, electronic control board faults and drainage problems. Most visits take one to four hours.
Start with the error code
Mini-splits monitor themselves. When a reading goes out of range, the head shows a code or blinks a light in a pattern, and the meaning differs between brands and even between model series. We look up your model’s service data and test the circuit the code points to: a temperature sensor, the communication link between the indoor and outdoor units, a pressure or current protection, the outdoor fan.
A code names a symptom, not always a part. A communication error can come from a corroded terminal at the outdoor unit rather than a failed board, and near the coast, damp, salty air on outdoor connections is a common culprit. Testing before replacing keeps you from paying for a board you did not need.
Symptoms and likely causes
| What you notice | Likely cause | What the repair involves |
|---|---|---|
| Mini-split not heating or cooling | Sensor fault, outdoor unit not starting, low refrigerant | Sensor and voltage tests, leak search |
| Error codes on the display | Sensor, wiring, communication fault or protection trip | Testing the circuit the code names |
| Unusual noises from the units | Dirty or unbalanced blower wheel, worn fan motor, loose bracket | Cleaning, motor replacement, re-securing |
| Water leaking from the indoor unit | Blocked drain, head out of level, failed condensate pump | Drain clearing, re-leveling, pump replacement |
| Remote control not working | Batteries, receiver, control board | Receiver or board testing |
| Musty smell, weak airflow | Growth on the coil and blower wheel | Deep cleaning of the head |
Inverter compressors and control boards
Most mini-splits use an inverter-driven compressor: an electronic board varies the compressor’s speed instead of switching it on and off. That is why they run quietly and efficiently, and it is also why many failures that look like a dead compressor turn out to be in the electronics. We measure the compressor windings, the board’s outputs and the sensor readings against the manufacturer’s tables before naming the failed part. Replacement boards for some models take time to arrive, and we tell you what to expect before ordering.
When the compressor itself has failed on an older unit, repair may not be the sensible spend. We put both options in writing and you decide; our installation page covers what a new system involves.
Line-set leaks
The flare connections at each indoor head and at the outdoor service valves are the usual leak points, especially where a flare was poorly made or the lines vibrate. Outdoors, salt air corrodes fittings and valves over time. A repair means finding the leak, remaking the flare or replacing the fitting, a nitrogen pressure test, evacuation and recharging by weight. The full sequence is on our refrigerant leak repair page.
Cleaning heads in a damp climate
Indoor heads in cool, damp homes grow a film on the coil and inside the barrel-shaped blower wheel. You see black specks at the outlet, smell it when the unit starts and feel weaker airflow; in time the wheel goes out of balance and starts to rattle. A deep cleaning takes the covers off, washes the coil and wheel in place with the electronics protected, and flushes the drain. Our page on musty smells covers other sources.
Before you call
- Put fresh batteries in the remote and check the mode (Cool, Heat, Dry or Auto) and the setting.
- Rinse the washable mesh filters behind the head’s front cover.
- Check the breaker and the outdoor disconnect.
- Make sure the outdoor unit is not buried in leaves or blocked by stored items.
- Do not spray water into the head or open its covers with the power on.
Price
Most mini-split repairs run $200 to $1,200, depending on the part, the brand and how much access work is needed. You get a written estimate before work starts, and the repair carries a warranty on parts and labor.