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Warranty Information

All units come with full manufacturer warranty covering parts. Register your warranty within 60 days of purchase for extended coverage.

R-32 System Compatible 21" Wide Cabinet Multi-Position Installation Multi-Speed ECM Blower 10-Year Parts Warranty

Performance at a Glance

4.0

Ton

Nominal Capacity

48,000

BTU/h

Cooling Capacity

3/4

ECM Blower

21"

Wide

Cabinet Size

R-32

Refrigerant

Key Features

Why this air handler works

Built-In R-32 Evaporator Coil

All-in-one air handler with factory-installed evaporator coil and TXV. Pairs with an R-32 outdoor condenser or heat pump to complete a split system — no separate coil to buy.

Multi-Position Installation

Installs four ways — upflow, downflow, horizontal-left, horizontal-right. A single unit fits basements, closets, attics, crawlspaces, and utility rooms. One air handler, every scenario.

3/4 HP Multi-Speed ECM Blower

The 3/4 HP electronically commutated motor matches airflow precisely to heating and cooling demand. ECM blowers use far less electricity than old PSC motors, especially during long low-speed operation.

Engineered for R-32 Systems

Built for R-32 outdoor condensers and heat pumps — the new residential refrigerant replacing R-410A. Not compatible with R-410A or R-22 equipment. For R-32 installs only.

Accommodates Electric Heat Kits

Field-installable electric heat kits (sold separately) add supplemental heat for a heat pump, or serve as primary heat in all-electric homes. Kit sizing depends on your heating load and outdoor unit pairing.

Backed by Ace Air

10-Year Parts Limited Warranty when registered within 60 days of installation by a licensed HVAC pro. Simple, documented, backed.

The AMST multi-position air handler is designed for 4.0 ton R-32 systems and supports upflow, downflow, or horizontal installation. A direct-drive 9-speed ECM blower motor and factory-installed thermal expansion valve match airflow and refrigerant flow to system demand, and a built-in A2L refrigerant sensor monitors for leaks. AHRI Certified and ETL Listed; UL 60335-2-40 compliant.

A2L refrigerant compliance — designed and tested to UL 60335-2-40 requirements for R-32 mildly flammable refrigerant safety.
Factory-installed RDS leak sensor — designed for the lifespan of the coil to detect refrigerant leaks.
Direct-drive 9-speed ECM blower motor — variable airflow speeds for matched comfort and efficiency.
Internal factory-installed TXV — thermal expansion valve included for cooling and heat pump applications.
All-aluminum evaporator coil — high-performance coated fin stock for durability and heat transfer.
Multi-position installation — upflow, downflow, or horizontal — adapts to closets, attics, or basements.
Coil mounting track — allows quick repositioning during install or service.
Low cabinet air leakage — less than 2.0% at 1.0 inch H₂O per ASHRAE Standard 193.
Optional electric heat kits — field-installed kits from 3 kW to 25 kW for supplemental heating.

Why R-32 Refrigerant?

R-32 versus the older R-410A standard

Feature	R-32 (This Unit)	R-410A (Old Standard)
Energy Efficiency	Up to 10% higher	Baseline
Refrigerant Charge Required	Up to 30% less	Standard
Thermodynamic Performance	Superior heat transfer	Standard
Regulatory Status	Future-ready	AIM Act phase-down

Complete Specifications

AAD-AMST48CU13 — 4.0 Ton Multi-Position ECM Air Handler (R-32)

Model & Configuration
Model Number	AMST48CU13
Nominal Capacity	4.0 Ton
Cooling Capacity (BTU/h)	48,000
Cabinet Size	C (21" wide)
Installation	Multi-Position — Upflow, Downflow, Horizontal Left, Horizontal Right
Refrigerant Compatibility	R-32 only
Evaporator Coil	Built-in, factory-installed with TXV
Blower
Blower Motor HP	3/4 HP
Blower Motor FLA	5.7
Blower Type	Multi-Speed ECM
Electrical
Voltage	208/240V Single-Phase / 60 Hz
Minimum Circuit Ampacity (MCA)	7.1 A
Maximum Overcurrent Protection (MOCP)	15 A
Electric Heat Kit	Field-installable (sold separately)
Line Set & Connections
Liquid Line Size	3/8"
Suction Line Size	7/8"
Physical
Shipping Weight	153 lbs

Dimensions

Cabinet dimensions for AAD-AMST48CU13

21 1/8"

Width

21"

Depth

58"

Height

Warranty Coverage

Coverage that kicks in at registration

Year Parts Limited Warranty

Documentation

Manufacturer spec sheets for this product

Air Handler Spec Sheet
PDF — Tap to download

Frequently Asked Questions

What is an air handler?

An air handler is the indoor half of a split HVAC system. It houses the blower motor that circulates air through your home — and in all-in-one units like the AAD-AMST48CU13, a factory-installed evaporator coil. It pairs with an outdoor condenser (cooling only) or a heat pump (heating plus cooling). No fuel burning — an air handler relies on refrigerant and supplemental electric heat kits for heat.

Air handler vs. gas furnace — what's the difference?

A gas furnace burns natural gas or LP to produce heat. An air handler has no burner. Air handlers are the standard indoor partner for heat pump systems and for all-electric homes where electric heat strips do the heating. Gas service + prefer gas heat? Go furnace. Heat pump or all-electric home? Go air handler.

What size home does a 4.0-ton air handler serve?

4.0-ton units typically handle homes in the 2,100–2,600 sq. ft. range for cooling. Heating load, climate zone, insulation, and window area all change the math — a professional Manual J load calculation is the right way to size. The air handler's tonnage should match the outdoor condenser or heat pump tonnage.

What does "Multi-Position" mean?

The AAD-AMST48CU13 installs four ways: upflow (air enters bottom, exits top — basement/utility room), downflow (air enters top, exits bottom — attic), horizontal-left and horizontal-right (air moves sideways — crawlspaces and tight attics). One SKU, every configuration. No position-specific ordering.

What is ECM and why does it matter?

ECM stands for electronically commutated motor. Compared to older PSC motors, ECM blowers use less electricity, run quieter, and vary speed smoothly to match demand. Over long heating and cooling seasons the efficiency difference adds up to real savings on your electric bill.

Can I add electric heat strips?

Yes. The AAD-AMST48CU13 accommodates field-installable electric heat kits (sold separately). Typically added for heat pump backup heat in cold climates, or as the primary heat source in all-electric homes. Your contractor picks the kW rating based on your heating load and local electrical service.

Can I use this with an R-410A condenser?

No. R-32 only. R-32 and R-410A run at different pressures with different oils — mix them and you'll damage the equipment and void warranties. Pair with an R-32 condenser or heat pump, period.

How do I know if this cabinet size fits?

Cabinet widths: A = 14", B = 17-1/2", C = 21", D = 24-1/2". The AAD-AMST48CU13 is a Cabinet C (21" wide). The cabinet has to fit both your install space and — if you're replacing — your existing ductwork connections. Your contractor can verify fit.

How do I register for the 10-year warranty?

Register at Ace Air's warranty page within 60 days of installation. You need: model number (AAD-AMST48CU13), serial number (from the data plate), install date, and installing contractor info. Miss the 60-day window and you drop to the shorter base warranty.