This is a Carrier Performance Series 4-way ceiling cassette indoor unit — the indoor component only. It's built for homeowners or contractors assembling a ductless zone who need the matched indoor head; the outdoor condenser, line set, grille, and mounting sleeve are sold separately.
The Carrier 45MBCA Performance Series cassette is engineered to drop into a suspended ceiling for a clean, low-profile look with no exposed indoor wall unit. It pairs with Carrier outdoor condensers under AHRI-certified combinations; system-level SEER2, HSPF2, and EER2 ratings are determined by that specific outdoor pairing, not by this indoor unit alone. 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
- Indoor Unit: Carrier Performance Series 4-Way Ceiling Cassette, model 45MBCAQ18XA3 (family 45MBCA, size 18K)
- Outdoor condensing unit: sold separately — must be an AHRI-matched Carrier outdoor unit
- Decorative grille: sold separately (see listing title note — grille sold sep.)
- Ceiling mounting sleeve/frame: sold separately
Installation Requirements & Accessories
- Voltage/Power Supply: 208/230V; 1Ph; 60Hz
- Refrigerant: R-454B (Puron Advance), A2L mildly flammable classification — requires EPA Section 608-certified technician handling
- Line set: NOT included — must be purchased separately and sized to match your specific outdoor unit pairing
- Grille: NOT included — sold separately per listing title
- Mounting sleeve/ceiling frame: NOT included
- Not compatible with 115V-only circuits
- Not a stand-alone system — requires a matched outdoor condenser to operate; SEER2/HSPF2/EER2 depend entirely on that pairing
- Professional installation required — this is not a DIY pre-charged kit
Pro-Installer Tip
Flare connections on R-454B systems are unforgiving of shortcuts. A flare nut torqued by feel instead of spec is the single most common cause of a slow refrigerant leak that shows up as reduced capacity or an "E" communication fault months after startup. Use a digital torque wrench set to the fitting manufacturer's spec and re-check the flare surface with an eccentric flaring tool before assembly — a scored or out-of-round flare will never seal reliably, no matter how hard it's torqued. Because this unit uses A2L mildly flammable refrigerant, EPA Section 608 certification and adherence to A2L handling procedures are mandatory for anyone brazing, evacuating, or charging this system.
Key Benefits
- Inverter-driven system compatibility for variable-speed comfort (inverter behavior determined by paired outdoor unit)
- Sound levels as low as 23.5 decibels for quiet operation in occupied spaces
- Four fan-speed settings with Follow Me temperature sensing and adjustable air direction
- Low-profile ceiling cassette design — no ductwork, no ceiling tear-out or repainting required
- Compatible with Puron Advance (R-454B) refrigerant, rated 75% lower global warming potential than legacy refrigerants
- Wireless remote controller included
Technical Table
| Spec | Value | Unit |
|---|---|---|
| Model | 45MBCAQ18XA3 | — |
| Indoor Unit Architecture | Traditional 4-Way Ceiling Cassette | — |
| Cooling Rated Capacity (DOE A2 - 95°F) | 16000 | Btu/h |
| Heating Rated Capacity (DOE H12 - 47°F) | 19000 | Btu/h |
| Power Supply | 208/230V;1Ph;60Hz | — |
| Refrigerant Type | R-454B (Puron Advance) | — |
| Sound Level (as low as) | 23.5 | dBA |
| SEER2 / HSPF2 / EER2 | Dependent on paired outdoor unit | — |
| DIY Status | No — Professional Installation Required | — |
| Grille | Sold Separately | — |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
- Fits a suspended/drop-ceiling installation as a traditional 4-way cassette — this is NOT a slim one-way cassette designed for direct fit between standard 16-inch on-center joists.
- Compatible with 208/230V single-phase, 60Hz dedicated circuits. Not compatible with 115V-only circuits.
- Must be paired with an AHRI-certified matching Carrier outdoor unit to operate — this indoor cassette is not a stand-alone system.
- Grille is NOT included with this listing — must be ordered separately.
- Line set is NOT included — size and length must be confirmed against your outdoor unit pairing.
- Ceiling mounting sleeve/frame is NOT included.
FAQ
What breaker size do I need for this system?
[NEEDS VERIFICATION] — the MCA/MOP data provided is organized by outdoor unit size tables, not tied explicitly to this indoor model. Confirm breaker sizing against the matched outdoor unit's nameplate before installation.
Is professional installation required to keep the warranty valid, or is this a true DIY kit?
This is not a DIY kit. It uses R-454B refrigerant (A2L classification) and requires professional installation by a licensed HVAC contractor to maintain the manufacturer warranty.
Is the line set included, and if not, what size do I need to buy?
The line set is sold separately. Manufacturer piping data for the 18K size class lists a liquid line and suction line, but the exact pairing depends on which outdoor unit you match to this indoor cassette — confirm sizing with your installer before ordering. [NEEDS VERIFICATION] for this specific indoor/outdoor pairing.
Will the ceiling cassette fit between standard 16-inch on-center joists?
This is a traditional 4-way cassette, designed to drop into a suspended/drop ceiling grid rather than fit directly between 16-inch on-center joists. It requires a ceiling cavity and the separately sold mounting sleeve and grille. [NEEDS VERIFICATION] for exact ceiling cutout dimensions on this size.
Does this system work in cold climates (low-ambient heating)?
Heating performance depends on the paired outdoor unit. Manufacturer data shows heating capacity ratings at 47°F, 17°F, and 5°F test conditions across various outdoor unit sizes, but low-ambient performance for this exact indoor/outdoor combination is [NEEDS VERIFICATION].
Compliance & Warranty
Installation by a licensed HVAC professional is required to maintain warranty. This unit uses R-454B (A2L mildly flammable) refrigerant and must be installed, evacuated, and charged by an EPA Section 608-certified technician. Carrier's Consumer Choice Warranty applies upon timely registration on eligible equipment: select either a 10-year parts-only limited warranty, or a 5-year parts plus 3-year labor limited warranty. Confirm exact warranty terms and registration requirements in the manufacturer documentation referenced above.
