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Product Description 
 
MRCOOL® Signature Series 42K Multi-Position Air Handler (230V)
The MRCOOL® Signature Series 42K Multi-Position Air Handler is engineered for homeowners and installers who need strong airflow, quiet performance, and installation flexibility in a 3.5-ton split-system setup. Designed to pair perfectly with MRCOOL® Signature Series top-discharge condensers and heat pumps, this air handler supports upflow, downflow, and horizontal installations, making it a reliable choice for both new construction and retrofit projects. 
At the heart of the system is a high-efficiency ECM blower motor, delivering smoother airflow, improved humidity control, and reduced electrical consumption compared to traditional blower designs. When paired with a compatible condenser or heat pump, the system provides consistent, year-round heating and cooling while helping homeowners keep long-term energy costs under control.
The cabinet is constructed from heavy-gauge galvanized steel to resist corrosion and wear over time. Inside, copper “A” coils with enhanced aluminum fins maximize heat transfer and moisture removal, improving system efficiency and indoor comfort. Internal thermal insulation minimizes condensation and reduces sound transmission, allowing the unit to operate quietly at just 54 dBA, ideal for residential environments where noise matters.
Installation is straightforward thanks to an installer-friendly design that reduces labor time and simplifies service access. A built-in filter rack allows for quick maintenance, while support for optional electric heat kits provides added heating capacity in colder climates. The system is also compatible with most third-party smart thermostats, giving homeowners flexibility without locking them into proprietary controls.
Backed by a 10-year limited parts warranty, the MRCOOL® Signature Series 42K Multi-Position Air Handler delivers dependable airflow, efficient performance, and flexible installation—making it an excellent indoor solution for 3.5-ton residential HVAC systems.
 
 SYSTEM COMPATIBILITY
✔ MRCOOL® Signature Series top-discharge AC condensers
✔ MRCOOL® Signature Series heat pump condensers
✔ Split-system HVAC applications
✔ Optional electric heat kits
1. 5kW,      Model- MCAEHFD5X1AA
2. 7.5kW,   Model- MCAEHFD7X1AA
3. 10kW,    Model- MCAEHFD10X1AA
✔ R-454B refrigerant systems
 
 TECHNICAL SPECIFICATIONS 
Brand: MRCOOL
Series: Signature Series
Model: MCAEAMPEF42C21AA
Unit Type: Air Handler
Mount Type: Multi-Position
 
Capacity: 42,000 BTU
Tonnage: 3.5 Ton
Airflow: 1,254 CFM
 
Voltage: 208/230V
Phase: 1
Frequency: 60 Hz
Max Breaker: 10A
Min Circuit Ampacity: 7.2A
 
Refrigerant Type: R-454B
 Liquid Line: 3/8”
Suction Line: 3/4”
Drain Connection: 3/4”
 
Blower Motor Type: ECM
Blower Motor HP: 3/4 HP
Blower Speeds: 5
Blower RPM: 1,040
Sound Rating: 54 dBA
 
Filter Type: Replaceable
Filter Size: 18 × 21 × 1
 
Metering Device: Orifice
 Auxiliary Heat Included: No
Auxiliary Heat Available: Yes
Aux Heat Sizes: 5kW, 7.5kW, 10kW
 
Certifications: AHRI, UL, CSA, ETL
ENERGY STAR®: No 
Warranty:
• 10-Year Limited Parts Warranty
 
 DIMENSIONS & WEIGHT
Net Dimensions:
• Width: 19.625”
• Depth: 22”
• Height: 45.75”
Net Weight: 131 lbs
Shipping Dimensions:
• Width: 22.83”
• Depth: 25.6”
• Height: 47.875”
Shipping Weight: 144 lbs
 
frequently Asked Questions 
What systems work with this air handler?
This unit pairs with MRCOOL Signature Series top-discharge AC and heat pump condensers.
 
Does this air handler use a variable-speed blower?
Yes. It features a high-efficiency ECM blower motor with 5 speed settings.
 
Can this unit be installed horizontally?
Yes. It supports upflow, downflow, and horizontal installations.
 
Is it compatible with R-454B refrigerant? 
Yes. The unit is fully designed for R-454B systems.
 
Can auxiliary heat be added?
Yes. Optional 5kW, 7.5kW, and 10kW electric heat kits are supported.
 
Why Buy From MRCOOL DIRECT?
When you order from MRCOOL Direct, you get:

✅ Authorized MRCOOL® dealer – Your warranty is protected
✅ Factory-fresh units – No refurbished or mystery sources
✅ Fast U.S. shipping – Most in-stock items ship in 1–3 business days
✅ Financing options – Make high-efficiency comfort more affordable
✅ Real product support – Help with sizing, line set selection, and DIY questions
✅ No third-party marketplace middlemen – Just genuine MRCOOL® systems from a trusted MRCOOL® dealer.

BUY DIRECT!
Feel Free to call us anytime. Family Friendly help just a dial away. We love talking HVAC615-553-8118
Family owned & USAs #1 MRCOOL® Authentication Dealer.
 
Brand:MRCOOL®Category:AIR HANDLERSKU:MCAEAMPEF42C21AATags:230V Air Handler, 3.5 Ton Air Handler, 42K Air Handler, Air Handler, ECM Blower, Indoor Unit, MCAEAMPEF42C21AA, MRCOOL, Multi-Position Air Handler, R-454B, Residential HVAC, Signature Series