A ductless mini-split pairs an outdoor unit with one or more indoor units, usually mounted high on a wall, joined by a thin refrigerant line, a control cable and a drain through a small hole in the wall. It is a heat pump, so the same system cools on hot afternoons and heats on winter nights in the 40s. In Hayward it solves rooms that ducts never reached and homes that never had ducts. We install, repair and maintain single-zone and multi-zone systems.
Where a mini-split makes sense in Hayward
- Additions to slab ranch homes. Many 1950s ranch homes sit on a slab, with all their ducts in the attic. Running a duct out to a back addition or a converted garage is often awkward, and the end of a long run gets weak airflow. One indoor unit solves the room.
- Hill-home rooms that fight the main system. A bonus room, an upstairs bedroom or a room with a wall of glass facing the bay often runs hotter or colder than the rest. Its own unit lets it have its own setting.
- Homes with wall heaters or no ducts. A multi-zone system adds cooling and efficient heat without opening ceilings for ductwork.
- Townhomes. Little attic or closet space makes slim indoor units and a compact outdoor unit easier to fit.
- Heat-wave nights. In a house without central air, one unit in the main bedroom keeps that room cool enough to sleep when a heat wave lingers.
Single-zone or multi-zone
A single-zone system is one outdoor unit and one indoor unit. It is the simplest layout, and if it fails, only one room is affected. A multi-zone system runs two or more indoor units from one outdoor unit, which saves space outside but puts every room on one compressor. Sizing matters more than with central air because each indoor unit serves one room. One that is too big for a small bedroom cycles on and off and leaves the air clammy; one too small for a sunny hill-home living room falls behind in a heat wave.
Installing on a slab home
With no crawlspace, the lines and drain on a slab house usually run down the outside wall inside a paintable cover to the outdoor unit. The drain needs a steady downhill slope; where the wall layout does not allow one, a small condensate pump does the job. The outdoor unit goes where it gets free airflow and stays easy to service, away from bedroom windows where possible. The lines are pressure-tested and evacuated before the refrigerant valves are opened. If you are still weighing ductless against central air, see AC installation.
Problems we fix most
Mini-split not cooling. The unit runs but the air is warm, or it shuts off quickly. Start with the filters behind the front panel; clogged ones cut airflow sharply. If clean filters do not help, the likely cause is a refrigerant leak, often at a flare connection, or a compressor or control fault. Refrigerant work is for a technician.
Mini-split leaking water. Water drips from the indoor unit, the wall behind it is damp, or you hear gurgling. The drain line is usually partly blocked or has lost its slope. A dirty coil or blower wheel, or a unit that has tilted off level, can also push water out of the front.
Error codes. Blinking lights, a code on the display, or a unit that ignores the remote. Codes differ by brand and usually point to a sensor, a communication fault between the indoor and outdoor units, or a protective shutdown. Note the code before you reset anything and tell us when you call, so we can bring the right parts.
A musty smell when the unit starts usually means mould on the blower wheel or the coil. A deep cleaning removes it; our guide to a musty smell from vents explains why it grows.
Keeping a mini-split clean
| How often | What to do |
|---|---|
| Every 2–4 weeks in heavy use | Rinse or vacuum the indoor filters and let them dry before refitting |
| Monthly | Wipe the indoor unit’s casing and louvres with a soft, damp cloth |
| Each season | Check that the drain outlet outside runs freely and clear leaves from the outdoor unit |
| Once a year | Professional coil and blower-wheel cleaning with a full system check |
Brands and how we work
We service all major ductless brands, including Mitsubishi Electric, Daikin, Fujitsu, LG, Samsung and Gree, plus the ductless lines sold under Carrier and Trane. We are independent, not affiliated with any manufacturer. The price is flat and given after diagnosis, repairs use manufacturer-recommended parts and carry our warranty, and a mini-split also works as a heat pump, so its heating side is covered on our heat pump service page.