Ductless Mini-Split Installation and Repair in the South Bay
Mitsubishi mini-splits for additions, garages, ADUs and the rooms your ducts miss, installed and serviced by the family-run Morgan Hill team since 2009.
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Mini-Splits Heat and Cool the Rooms Your Ducts Don’t Reach
A ductless mini-split is a heat pump with no ductwork. An outdoor unit connects through a thin refrigerant line to one or more indoor heads, and each head heats and cools its own room. It makes sense for additions, converted garages, ADUs, older homes without ducts, and any room your current system never cooled properly.
We install and service mini-splits across 13 South Bay and Santa Cruz County cities, from Morgan Hill and San Jose to Watsonville and Ben Lomond, and Mitsubishi is our go-to brand for ductless work.
Where a Mini-Split Makes Sense
The rooms we get called about are rarely a surprise. Converted garages, additions built over a slab, back bedrooms that were never on the original duct run, and older homes that never had ducts at all.
- Additions and ADUs. Extending an existing duct system into a new space often means a bigger system and a lot of cutting. A single-zone mini-split conditions the new room on its own.
- Garages and workshops. One head and one outdoor unit, no ducts, and a thermostat that only cares about that room.
- Older homes without ducts. Adding ductwork to a finished home is invasive and expensive. A mini-split needs one small opening per head.
- The room that never feels right. If one bedroom runs hot every summer on an otherwise fine system, a single head can fix it without touching the rest of the house.
A mini-split is not always the right call. If your home already has sound, well-sealed ducts, a ducted heat pump is often simpler and cheaper for the whole house. We will tell you which side your house leans toward when we see it.
Single-Zone or Multi-Zone
Single-zone means one outdoor unit and one indoor head for one space. Multi-zone means one outdoor unit feeding several heads, each with its own control, so the bedrooms can run at night while the living room sits idle.
Our records include 2-zone and 3-zone Mitsubishi systems in San Jose and Los Altos, and multi-zone outdoor units set in Los Altos and San Martin in 2026. A few jobs were ducted mini-splits, where the indoor unit feeds short duct runs instead of mounting on the wall. Indoor heads also come as wall-mounted, ceiling cassette, floor-mounted and concealed-duct styles, so the room usually decides the style.
Multi-zone adds up fast. One head is affordable, and covering a four-bedroom two-story home with enough heads for even comfort costs real money. Under-zoning is the other mistake: too few heads for the layout leaves rooms uneven. We size each room properly, not by a square-footage rule of thumb.
Comparing brands before you decide? Our view is that the installer matters more than the badge. Mitsubishi is what we install most, and our records also include Fujitsu, Bryant and Daikin systems we have serviced.
Heating and Cooling From One Unit
Most mini-splits are heat pumps. In summer the unit moves heat out of the room. In winter it moves heat in, using electricity to carry heat instead of burning gas to make it. One system, one outdoor unit, both seasons.
South Bay winters are mild, so you do not need the extreme cold-climate lines built for single-digit temperatures. A mountain property in the Santa Cruz hills is the exception worth a conversation.
There is no duct network to leak, either. ENERGY STAR estimates that 20% to 30% of the air moving through a typical duct system is lost to leaks and poor connections. A mini-split delivers air straight into the room. For a deeper look at the heating side, see our heat pump hub.
How We Install a Mini-Split
A mini-split lives or dies on where the head goes and how the line set is run. That is decided on site, not from a brochure.
- We look at the rooms. Which space needs conditioning, where the head should mount, where the outdoor unit can sit, and how the refrigerant line will get from one to the other.
- We size it with a real load calculation. Oversized heads short-cycle and never dehumidify properly. Undersized ones never keep up.
- You get a free written estimate. The person who quotes your job is a working installer, and our own crew does the install.
- We set the equipment. Outdoor unit on a pad or brackets, indoor head on the wall, insulated line set, condensate drain, and the electrical connection. Zone count, line-set run and electrical work are what move the price.
- We commission and register it. The system gets charged and tested, and the equipment is registered so the manufacturer warranty stays valid.
- It is backed in writing. Installations carry a three-year labor warranty on top of the manufacturer’s coverage.
Install time depends on the head count and the line-set run. In our job records, a single-head install was done in one day. Multi-zone installs mostly ran one to three working days, and the largest multi-head projects ran closer to a week. Permit requirements vary by city and scope, so ask us what applies at your address.
Mini-Split Repair and Maintenance
Every head has a filter that needs cleaning, and the outdoor coil, the condensate drain and the wiring between head and outdoor unit all need attention over time.
Our job records include a condensate pump replacement, zone cable repair and routine mini-split maintenance. If yours is blowing weak air, leaking at the head, throwing an error code or not heating, call us with the make and model.
Repair visits start with a $110 diagnostic that goes toward the repair if you move forward. You get an upfront price in writing before any work starts, and repairs carry a two-year labor warranty. Our maintenance plan is $15 a month per system with two tune-ups a year, and a mini-split can go on it as a system. A tune-up covers every indoor head and its filters. Tell us how many outdoor units and heads you have and we will confirm how it is counted.
Rebates, Financing and Honest Numbers
Heat pump incentives change constantly. State programs, utility programs and federal credits open, close and change their rules as funding runs out. Whether a given mini-split qualifies depends on the program, your utility and the exact model, so we check what is open before you commit and tell you what you actually qualify for.
Our heat pump rebate guide covers what South Bay homeowners can still get, and the federal tax credit explainer covers what has closed. For monthly payments, see our financing page. Wisetack lets you check options with a soft credit check that does not affect your score.
Getting other bids? Good. Here is how to compare heat pump quotes so you can tell a real number from a cheap one that leaves out the work. Replacement estimates are free, and you can call or text (408) 497-0444. Modern Air is licensed and insured, CSLB #935704.
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Frequently Asked Questions
How much does a ductless mini-split cost?
It depends on how many zones you need, how far the line set has to run, and what electrical work the install requires, so we price it after we see the rooms. Estimates on new systems are free, and the person who quotes the job is the installer, not a commissioned salesperson. Financing is available through Wisetack on qualifying work.
Do I need ductwork to install a mini-split?
No. An outdoor unit connects to each indoor head through a slim refrigerant line and a small opening in the wall, so there is no duct network to build, seal or balance. That is why mini-splits suit additions, converted garages, ADUs and older homes that never had ducts.
Does a mini-split heat as well as cool?
Yes. Most mini-splits are heat pumps, so the same unit cools in summer and heats in winter. South Bay winters are mild enough that a standard heat pump model handles them, and you rarely need the extreme cold-climate lines built for much colder regions.
Should I choose a single-zone or multi-zone system?
Single-zone fits one space such as a garage, ADU or addition. Multi-zone runs several indoor heads from one outdoor unit, which suits a few separate rooms. We decide by the layout and how you use each room, because head count and placement affect comfort more than the brand name does.
Which mini-split brands do you install?
Mitsubishi is our go-to for ductless. Modern Air is also a Trane dealer, and we can quote other major brands. We service other ductless brands too, and our job records include Fujitsu, Bryant and Daikin systems. We only install equipment we can register and warranty, because manufacturers will not honor the warranty on units bought online.
What warranty comes with a mini-split installation?
Installations carry a three-year labor warranty from Modern Air on top of the manufacturer’s equipment warranty, and repairs carry a two-year labor warranty. When a problem traces back to our workmanship, we have honored it even after the warranty ran out.
What does a mini-split repair visit cost?
Repair visits start with a $110 diagnostic that goes toward the repair if you move forward. After the diagnosis you get an upfront price in writing before any work starts.
Are there rebates for ductless mini-splits?
Sometimes. Heat pump incentives from the state, your utility and other programs open and close as funding runs out, and eligibility depends on the program and the exact equipment. We check what is open before you commit and tell you plainly what you qualify for.
Can a mini-split go on your maintenance plan?
Yes, a mini-split can go on the plan as a system. It costs $15 a month per system and includes two tune-ups a year, and a mini-split visit covers every indoor head and its filters, not just the outdoor unit. Tell us how many outdoor units and heads you have when you call 408-497-0444 and we will confirm how it is counted before you sign anything.
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