Air-Con | 42,000 BTU | 20 SEER | Mixed Indoor Heads | 3-Zone Multi-Zone Mini Split System | 208-230V | AMSCI4H4S42-3ZONE

This is a 3-zone ductless mini split system for cooling and heating three separate rooms from one outdoor condenser. It's built for homeowners who need independent temperature control in three spaces — bedrooms, additions, or a multi-room retrofit — without running new ductwork.

The AMSCI4H4S42 outdoor condenser is AHRI-certified and Energy Star listed as part of Air-Con's Multi Split Series, pairing with up to three or four indoor heads depending on configuration. This listing covers 3-zone combinations mixing wall-mounted (ABXEM), concealed duct (ASLEK), and ceiling cassette (ASLEC) indoor units. Note: If you would like to review the manufacturer Product Specifications, Warranty, Brochure, etc., for this system, please refer to the "Resources (System Manuals and Warranty)" Tab above on this page.

System Components

• 1x Outdoor Condenser Unit — Model AMSCI4H4S42, 42,000 BTU/h rated capacity, 20 SEER, 208-230V
• 3x Indoor Heads — available in wall-mounted (ABXEM4H4S09/12/18 series), concealed duct (ASLEK4H4S09/12 series), or ceiling cassette (ASLEC4H4S09/12 series), matched per the variant selected below
• Mixed-architecture zone combinations are supported — you can pair different indoor unit types (e.g., wall mount + cassette) on the same outdoor condenser, per the variant options listed

Installation Requirements & Accessories

• Voltage: 208-230V — this system is NOT compatible with 115V-only circuits
• Line set required for each indoor head — sold separately, size and length per manual (Resources tab)
• Professional installation required — this is a flare-connection system, not a pre-charged DIY kit
• Not compatible with outdoor unit/indoor unit combinations outside the published Air-Con compatibility table (e.g., do not pair AMSCI4H4S42 with indoor heads from unrelated series)
• Wall sleeve, mounting bracket, and disconnect box are NOT included unless explicitly listed in the variant

Pro-Installer Tip

Flare connections on multi-zone branch lines are a common source of slow refrigerant leaks and recurring "E1" communication faults if over- or under-torqued. Undersized torque leaves a micro-gap that bleeds refrigerant charge over months; overtorquing cracks the flare face. Use a digital torque wrench set to the flare size's spec, and pull the system down below 500 microns with a calibrated micron gauge before opening the service valves — a rushed vacuum leaves moisture and non-condensables in the line set, which shows up later as poor superheat and iced coils. Under EPA Section 608, any technician connecting or evacuating this system must be certified to handle refrigerant, and proper evacuation is not optional — it protects both the compressor and the SEER-rated efficiency you're paying for.

Key Benefits

• Inverter-driven variable speed compressor for steady temperature control across all three zones
• Independent zone operation — run one, two, or three indoor heads at different setpoints simultaneously
• Energy Star certified and AHRI-matched for verified performance ratings
• Mixed indoor unit architecture lets you match the head style (wall, duct, cassette) to each room's layout
• 20 SEER outdoor unit rating for the AMSCI4H4S42 condenser

Technical Table

Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.

Compatibility & Fitment

• Compatible with dedicated 208-230V single-phase circuits only — NOT compatible with 115V-only circuits.
• Matched to AHRI-certified 3-zone BTU combinations for the AMSCI4H4S42 outdoor unit (e.g., 9K+9K+9K, 9K+9K+12K, 9K+9K+18K, 12K+12K+12K per the manufacturer combinability table).
• Indoor heads available in wall-mounted (ABXEM), concealed duct (ASLEK), and ceiling cassette (ASLEC) architectures — select the combination matching your rooms in the Options table below.
• Line set is NOT included — this is not a pre-charged DIY kit.
• Not a listed match for indoor/outdoor model families outside the Air-Con Multi Split Series compatibility table.
• Wall sleeve and mounting bracket are NOT included unless stated in the specific variant.

Options & SKUs

FAQ

What breaker size do I need for this system?

[NEEDS VERIFICATION] — breaker size is not specified in the manufacturer data provided. Confirm the required circuit breaker size against the outdoor unit nameplate or installation manual before wiring.

Is professional installation required to keep the warranty valid, or is this a true DIY kit?

This is a standard flare-connection multi-zone system, not a pre-charged DIY kit. Professional installation by a licensed HVAC technician is required to maintain the manufacturer warranty.

Is the line set included, and if not, what size do I need to buy?

The line set is not included. Exact line set sizes per indoor head are [NEEDS VERIFICATION] — refer to the manufacturer installation manual in the Resources tab for the correct diameter and maximum run length per zone.

Will the ceiling cassette fit between standard 16-inch on-center joists?

Joist spacing compatibility for the ASLEC cassette models is [NEEDS VERIFICATION] in the manufacturer data provided. Confirm cassette dimensions against your joist bay before ordering.

Does this system work in cold climates (low-ambient heating)?

Low-ambient heating performance and minimum operating temperature are [NEEDS VERIFICATION] — not specified in the manufacturer data provided for this outdoor unit.

Compliance & Warranty

Installation by a licensed HVAC professional is required to maintain warranty. This system operates on a 208-230V circuit and uses standard flare connections requiring EPA Section 608 certified handling of refrigerant during installation and evacuation. Full warranty terms, manuals, and AHRI certificates are available in the "Resources (System Manuals and Warranty)" tab above. Ask us before you order if you're unsure which zone combination fits your space — we always reply back.