Ductless systems solve problems central air cannot: a 1940s house with no ducts, a hot bonus room over the garage, a new ADU in the backyard. Back2Cool HVAC handles mini split installation in Los Angeles and across the San Fernando Valley, plus repair and cleaning of existing systems. Our lead tech completed specialized HVAC training courses with Mitsubishi Electric, Daikin and Fujitsu, and ductless work is a big part of what we do every week.
Where a Ductless Mini Split Makes Sense
- Older homes without ducts. Many Spanish Revival, Craftsman and mid-century homes in LA were built with a wall heater and no ductwork. Running new ducts through plaster walls and a shallow attic is invasive. A mini-split needs only a small wall penetration per head.
- ADUs and guest houses. California's ADU laws have put a lot of backyard units on the map, and a mini-split is often the cleanest way to heat and cool one. Our guide to ADU HVAC with mini-splits in Los Angeles goes deeper.
- Garage conversions, home gyms and studios. Spaces that were never connected to the main system.
- Additions and remodels. When the existing central system cannot handle the extra square footage.
- Problem rooms. The upstairs bedroom that is always noticeably warmer than the rest of the house, or a sunroom that bakes every afternoon.
- Condos. Where a compact outdoor unit fits on a balcony or roof within HOA rules.
Weighing ductless against ducted for a whole house? Read mini-split vs. central air in Los Angeles.
Single-Zone vs. Multi-Zone Mini Splits
| Single-zone | Multi-zone | |
|---|---|---|
| Setup | One outdoor unit, one indoor head | One outdoor unit, two or more indoor heads |
| Best for | One room, ADU studio, garage, office | Several rooms or a whole house |
| Outdoor footprint | One unit per room served | One unit serves many rooms |
| Redundancy | Each system runs independently | Heads share one outdoor unit |
| Control | One room, one thermostat | Each zone set separately |
On larger multi-zone systems, a branch box (also called a branch distribution box) sits between the outdoor unit and the indoor heads. It splits the refrigerant circuit to each zone and simplifies the piping runs, which keeps long line sets shorter and makes future service easier.
Indoor Unit Styles
Wall-mounted heads
The most common and most affordable option. Mounted high on a wall, easy to service, and fine for most bedrooms and living areas.
Ceiling cassettes
Recessed into the ceiling with air delivered in several directions. A cleaner look in open living rooms and kitchens, but they need attic or ceiling access above.
Ducted (concealed) air handlers
A slim unit hidden in the attic, a soffit or a closet, feeding a few short duct runs. Good when you want to serve two or three adjacent rooms with no visible equipment.
Choosing Equipment
Our lead tech completed specialized training with Mitsubishi Electric, Daikin and Fujitsu, so we know how each manufacturer's systems are meant to be installed, piped and commissioned. When we quote, we compare a few things that matter more than the logo:
- Capacity range of each head, so small bedrooms are not served by oversized units
- Heating performance on cold Valley and foothill nights
- Indoor unit style options and noise levels for bedrooms
- Control options, from the handheld remote to wall controllers and app control
- Line set length limits for your layout
A Recent Project: 5-Zone Mitsubishi System
One of our recent jobs was a 5-zone Mitsubishi mini-split with a branch box. The scope included all five indoor units, the outdoor unit, refrigerant piping, electrical, condensate drains, and full startup and testing of every zone. Start to finish, it took about 2 days. That is a typical example of how we approach multi-zone work: plan the piping and drain routes first, keep penetrations clean, and test each head individually before calling it done.
Need it fixed today?
$55 service call with code LA55 — inspection, diagnosis and a clear price before any work. Open 7 days · 8 AM – 10 PM.
How We Install a Mini Split
- Load calculation and layout. We size each head to its room, rather than putting the same size everywhere. An oversized head short cycles and leaves the room clammy.
- Written quote with exact model numbers for the outdoor unit, every indoor unit and any branch box or accessories.
- Permit pulled where required.
- Clean mounting and routing. Line sets run in tidy covers, condensate drains sloped properly or routed to a pump.
- Proper flare connections. Flares are made and torqued to spec, then the system is pressure tested and evacuated with a deep vacuum. This step is where many leak problems begin when it is rushed.
- Startup and testing in cooling and heating, zone by zone.
- Walkthrough on the remote, filters and cleaning schedule, then floors uncovered and the site cleaned.
Mini Split Repair
Most ductless problems fall into a handful of categories. Many show up as a blinking light or error code on the indoor head, which helps narrow things down quickly.
Dirty filters and coils
The most common cause of weak airflow, poor cooling, and a frozen coil that then drips when it thaws. Filters should be rinsed regularly; the coil and blower wheel need professional cleaning. Our AC maintenance page covers mini-split deep cleaning.
Drain problems
A clogged drain line, a kinked hose, a failed condensate pump or a head that is not level can send water down the wall. These are usually quick fixes once found.
Refrigerant leaks at flare connections
Flare fittings that were cut, flared or torqued poorly during installation are a classic source of slow leaks, sometimes showing up a year or two later as gradually weaker cooling. Topping off refrigerant does not fix it. The leak has to be found and the connection remade correctly, then the system evacuated and recharged.
"These guys brought my split system back to life after some installers messed it upand its only two years old! They found the leak and fixed everything in one day. They did an amazing job!"
Arina D. · Google
Electrical and communication faults
Failed sensors, fan motors, control boards or wiring between indoor and outdoor units. These need diagnosis with a meter, not guesswork with parts.
"Back2Cool did a great job repairing my mini split. They found the issue quickly, explained what was wrong, and got everything working again the same day!! Professional, friendly, and reasonably priced!!!! Love their service ❤️❤️❤️ P.S.: Thank you for the gift!!!!"
Max A. · Thumbtack
Repair visits start with our $55 service call (code LA55), which includes an inspection, diagnosis and clear recommendations, with the $55 applied toward the repair if you go ahead.
Mini Splits Are Heat Pumps Too
Nearly every modern mini-split heats as well as cools. In LA's mild winters, that can replace an old wall heater or space heaters entirely. If you are thinking about heating the whole house this way, see our heat pump installation page.
Mini Split Service Across LA
We install and repair ductless systems in Sherman Oaks, Studio City, Hollywood, Glendale, Pasadena and throughout Los Angeles. Send us a photo of your space or your current system and we will tell you what makes sense. Call (626) 635-4095, 7 days a week, 8 AM to 10 PM.
