This is the indoor high-wall unit only — Carrier model 45MAHAQ33XA3, a 33,000 BTU/h component from the 45MAHA family. It's for homeowners and contractors building or replacing one zone of a ductless system who already have (or are sourcing separately) a matched Carrier outdoor unit, line set, and mounting accessories.
This listing is for the 45MAHAQ33XA3 indoor high-wall unit only — a 33,000 BTU/h wall-mounted fan coil designed to pair with a matched Carrier outdoor condenser in single or multi-zone ductless configurations. It uses Puron Advance™ (R-454B) refrigerant, an A2L mildly flammable classification per ASHRAE, which is why installation, evacuation, and refrigerant handling must be performed by an EPA Section 608-certified technician. 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 included in this listing: Carrier 45MAHAQ33XA3 high-wall fan coil, 33,000 BTU/h cooling class, wall-mounted architecture.
- Outdoor condenser: NOT included. Requires a matched Carrier 37MAHA-series (or AHRI-certified compatible) outdoor unit, sold separately.
- Wireless remote controller: included with the indoor unit per manufacturer data.
Installation Requirements & Accessories
- Voltage: 208/230V; 1-Phase; 60Hz (outdoor unit power supply, per manufacturer data for this size class).
- Refrigerant lines for this size: 3/8 in (9.52mm) liquid pipe, 3/4 in (19mm) suction pipe.
- Line set: sold separately. Not included with this indoor unit.
- Wall sleeve, mounting bracket, and grille: sold separately. Not included with this indoor unit.
- Professional installation is required. This is not a DIY pre-charged kit — refrigerant is R-454B (A2L), requiring licensed handling.
- Not compatible with outdoor units outside the AHRI-certified 45MAHA/37MAHA matched-pairing list.
- Refrigerant lines must not be buried in the ground, per manufacturer installation notes.
Pro-Installer Tip
Flare connections on R-454B systems are unforgiving of shortcuts — a slightly undersized or over-torqued flare on the 3/8 in liquid line or 3/4 in suction line for this size class is a common source of slow leaks that show up as capacity loss or nuisance fault codes months after startup. Torque every flare joint to the connection size's spec using a Digital Torque Wrench, and don't rely on "feel." Because this unit runs a mildly flammable A2L refrigerant, proper evacuation and leak-free connections aren't just a comfort issue — they're an EPA Section 608 handling requirement, and they protect the system's rated efficiency over its service life.
Key Benefits
- Inverter-driven compressor pairing (outdoor side) delivers variable-speed comfort rather than on/off cycling.
- Rated as quiet as 16 decibels at low fan speed, per manufacturer data for the Performance High Wall line.
- Compatible with Puron Advance™ (R-454B) refrigerant — 75% lower global warming potential than legacy refrigerants, per manufacturer data.
- Supports both single-zone and multi-zone system configurations from one indoor unit family.
- Rated heating performance published down to 5°F outdoor ambient (ODE H42) for this size, supporting cold-climate use when paired with a compatible outdoor unit.
| Spec | Value | Unit |
|---|---|---|
| Component Role | Indoor High-Wall Unit Only | — |
| Cooling Capacity (Rated, DOE A2 - 95°F) | 33000 | Btu/h |
| Heating Capacity (Rated, DOE H12 - 47°F) | 36000 | Btu/h |
| Cooling Capacity (Rated, DOE B2 - 82°F) | 37000 | Btu/h |
| Heating Capacity (DOE H32 - 17°F) | 30000 | Btu/h |
| Heating Capacity (ODE H42 - 5°F) | 35000 | Btu/h |
| SEER2 / HSPF2 / EER2 | Depends on paired outdoor unit | — |
| Voltage | 208/230V;1Ph;60Hz | V;Ph;Hz |
| Refrigerant Type | R-454B (Puron Advance) | — |
| Sound Level (Performance High Wall line, as low as) | 16 | dBA |
| Liquid Pipe Size | 3/8 (9.52) | in (mm) |
| Suction Pipe Size | 3/4 (19) | in (mm) |
| Cooling Operating Range | -22 to 122 (-30 to 55) | °F (°C) |
| MCA (Minimum Circuit Ampacity, 33K outdoor) | 34 | A |
| MOP (Maximum Overcurrent Protection, 33K outdoor) | 35 | A |
| DIY Status | No — Professional Installation Required | — |
| Zone Count | 1 (component of single or multi-zone system) | — |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
- Compatible with AHRI-certified outdoor units in the matched 45MAHA/37MAHA family for this size class.
- Compatible with dedicated 208/230V single-phase, 60Hz circuits (outdoor unit supply).
- Not compatible with 115V-only circuits — this size class requires 208/230V.
- Not a listed match for outdoor units outside the AHRI-certified 45MAHA/37MAHA pairing list.
- Line set is NOT included. This is not a DIY pre-charged kit.
- Wall sleeve, mounting bracket, and grille are NOT included.
FAQ
Is professional installation required to keep the warranty valid, or is this a true DIY kit?
Professional installation is required. This unit uses R-454B refrigerant (an A2L mildly flammable classification) and is not a pre-charged DIY kit. It must be installed and charged by a licensed HVAC professional.
Is the line set included, and if not, what size do I need to buy?
The line set is sold separately. For the 33K size, the manufacturer data lists a 3/8 inch (9.52mm) liquid line and a 3/4 inch (19mm) suction line for the matched outdoor unit.
What breaker size do I need for this system?
For the 33K outdoor unit paired with this indoor unit, the manufacturer lists a minimum circuit ampacity (MCA) of 34A and a maximum overcurrent protection (MOP) of 35A. Confirm exact breaker sizing against the nameplate of the specific outdoor unit you pair with this indoor head.
Does this system work in cold climates (low-ambient heating)?
The manufacturer data lists a rated heating capacity of 30,000 Btu/h at 17°F (DOE H32) and 35,000 Btu/h at 5°F (ODE H42) for this size when paired with a matched outdoor unit. Actual low-ambient performance depends on which outdoor unit you select.
What is the sound level of this indoor unit?
Carrier lists the Performance High Wall indoor unit line as operating as quietly as 16 decibels at the lowest fan setting; exact dBA for the 33K size specifically is [NEEDS VERIFICATION].
Compliance & Warranty
- Refrigerant: R-454B (A2L, mildly flammable classification). Installation by a licensed HVAC professional is required to maintain warranty.
- Carrier's Consumer Choice Warranty applies upon timely registration on eligible equipment: choice of a 10-year parts-only limited warranty, or a 5-year parts plus 3-year labor limited warranty, per manufacturer data.
- Select sizes are ENERGY STAR® certified; system-level efficiency (SEER2/HSPF2/EER2) depends on the specific outdoor unit paired with this indoor head.
- Installation must comply with ANSI/ASHRAE 15 and applicable local codes, per manufacturer installation notes.
