Lennox ML17KC2 Series Unit Information
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Lennox ML17KC2 Series Unit Information

Lennox ML17KC2 Series Unit Information

Units with all-aluminum coil
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Service Literature
ML17KC2 (R-454B) SERIES UNITS WITH ALL-ALUMINUM COIL
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer or
equivalent, service agency, or the gas supplier.
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
WARNING
Electric Shock Hazard. Can cause injury or
death. Unit must be properly grounded in
accordance with national and local codes.
Line voltage is present at all components when
unit is not in operation on units with single-
pole contactors. Disconnect all remote electric
power supplies before opening access panel.
Unit may have multiple power supplies.
WARNING
To prevent serious injury or death:
1. Lock-out/tag-out before performing maintenance.
2. If system power is required (e.g., smoke detector
maintenance), disable power to blower, remove fan
belt where applicable, and ensure all controllers
and thermostats are set to the "OFF" position before
performing maintenance.
3. Always keep hands, hair, clothing, jewelry, tools, etc.
away from moving parts.
UNIT INFORMATION
Corp. 100132
February 3, 2025

Table of Contents

Model Number Identification ...........................................5
Specifications ................................................................6
Unit Dimensions - Inches (mm) ....................................7
Typical Unit Parts Arrangement .....................................8
Component Specifications .............................................9
Installation .................................................................... 11
Unit Placement ............................................................ 11
New or Replacement Line Set ......................................14
Brazing Connections ...................................................17
Flushing Line Set and Indoor Coil ................................20
Installing Indoor Metering Device .................................21
Leak Testing the System .............................................22
Evacuating Line Set and Indoor Coil ...........................23
Maintenance ...............................................................27
Typical Field Wiring ......................................................29
Unit Start-Up ...............................................................30
System Refrigerant .....................................................30
Decommissioning ........................................................32
Start-Up Test Procedure ...............................................35
This unit must be matched with an indoor coil as
specified with AHRI. For AHRI Certified system match-
ups and expanded ratings, visit www.LennoxPros.com.
General Information
This ML17KC2 outdoor air conditioner with all-aluminum
coil is designed for use with R-454B refrigerant only. This
unit must be installed with an approved indoor air handler
or coil. For AHRI Certified system match-ups and expand-
ed ratings, visit www.LennoxPros.com. These instructions
are intended as a general guide and do not supersede
local codes in any way. Consult authorities having jurisdic-
tion before installation.
This outdoor unit is designed for use in systems that use
the following refrigerant metering device:
• Thermal expansion valve (TXV)
IMPORTANT: Special procedures are required for clean-
ing the aluminum coil in this unit. See page 27 in this man-
ual for information.
Page 1
ML17KC2

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Summary of Contents for Lennox ML17KC2 Series

  • Page 1: Table Of Contents

    UNIT INFORMATION ML17KC2 Corp. 100132 February 3, 2025 Service Literature ML17KC2 (R-454B) SERIES UNITS WITH ALL-ALUMINUM COIL Table of Contents Model Number Identification ...........5 Specifications ..............6 Unit Dimensions – Inches (mm) ........7 Typical Unit Parts Arrangement ........8 Component Specifications ..........9 Refrigerant Metering Device –...
  • Page 2 WARNING CAUTION • Do not use means to accelerate the defrosting pro- Under no circumstances shall potential sources of cess or to clean, other than those recommended by ignition be used in the searching for or detection of the manufacturer. refrigerant leaks.

  • Page 3: Refrigerating System

    IMPORTANT IMPORTANT When breaking into the refrigerant circuit to make When removing refrigerant from a system, either for repairs – or for any other purpose – conventional servicing or decommissioning, it is recommended good procedures shall be used. However, for flammable practice that all refrigerants are removed safely.
  • Page 4 IMPORTANT IMPORTANT Prior to beginning work on systems containing Where electrical components are being changed, they FLAMMABLE REFRIGERANTS, safety checks are shall be fit for the purpose and to the correct specification. necessary to ensure that the risk of ignition is minimized. At all times the manufacturer’s maintenance and service guidelines shall be followed.

  • Page 5: Model Number Identification

    NOTE – R-454B is an A2L refrigerant. The system installation must meet the following parameters based upon total refrigerant charge (line set included). TAmin (Total minimum conditioned area) is the minimum allowable conditioned area based upon the total system charge at sea level. Values must be multiplied by altitude adjustment factor at installed altitude. Qmin table refers to minimum airflow requirements during refrigerant leak mitigation by the refrigerant detection system, based upon total system charge.

  • Page 6: Specifications

    Specifications Size Nominal Tonnage Sound Rating Number Connections Liquid line (OD) - in. (Sweat) Suction line (OD) - in. 1-1/8 Compressor Type 2-Stage Scroll 2-Stage Scroll 2-Stage Scroll 2-Stage Scroll Refrigerant R-454B charge furnished 6 lbs. 4 oz. 6 lbs. 8 oz. 7 lbs.

  • Page 7: Unit Dimensions - Inches (Mm)

    Unit Dimensions – Inches (mm) 4-3/8 4-3/8 (111) (111) INLET 4-3/8 4-3/8 (111 111) OPTIONAL UNIT INLET INLET STAND-OFF KIT (4) COMPRESSOR (Field Installed) COIL DRAIN OUTLETS (Around perimeter of base) 6-3/8 SUCTION LINE 4-3/8 (162) CONNECTION (111) LIQUID LINE INLET 6-3/8 4-3/8...

  • Page 8: Typical Unit Parts Arrangement

    Typical Unit Parts Arrangement CAPACITOR (C12) GROUND LUG CONTACTOR 1-POLE (K1-1) CONTROL BOX FIGURE 1 Page 8...

  • Page 9: Component Specifications

    Using an Allen wrench rated at less than 50Rc risks rounding or breaking off the wrench, or stripping the valve stem recess. See the Lennox Service and Application Notes #C-08-1 for further details and information. Page 9...

  • Page 10: Service Valves

    SERVICE VALVES ANGLE AND BALL Operating Angle Type Service Valve: 1. Remove stem cap with an appropriately sized wrench. 2. Use a service wrench with a hex-head extension (3/16” for liquid line valve sizes and 5/16” for vapor line valve sizes) to back the stem out counterclockwise as far as it will go.

  • Page 11: Unit Placement

    Installation The slab should have a slope tolerance as described in Unit Placement figure 4, detail B. See Unit Dimensions on page 7 for sizing mounting slab, NOTE – If necessary for stability, anchor unit to slab. platforms or supports. ROOF MOUNTING CAUTION Install the unit a minimum of 6 inches (152 mm) above the...
  • Page 12 DETAIL B DETAIL A Install unit level or, if on a slope, maintain slope tolerance of 2 degrees INSTALL UNIT AWAY (or 2 inches per 5 feet [50 mm per 1.5 m]) away from building structure. FROM WINDOWS DISCHARGE AIR BUILDING STRUCTURE MOUNTING...

  • Page 13: Removing And Installing Louvered Panels

    Removing and Installing Louvered Panels WARNING To prevent personal injury, or damage to panels, unit or structure, be sure to observe the following: While installing or servicing this unit, carefully stow all removed panels out of the way, so that the panels will not cause injury to personnel, nor cause damage to objects or structures nearby, nor will the panels be subjected to damage (e.g., being bent or scratched).

  • Page 14: New Or Replacement Line Set

    RDS Control. Refer to the instructions provided with the sensor or the RDS controller to enable the second To obtain the correct information from Lennox, be sure to sensor. communicate the following points: New or Replacement Line Set •...
  • Page 15 A replace- LIQUID LIQUID LINE LINE LINE SERVICE VALVE ment filter drier is available from Lennox. See Brazing LIQUID LINE FILTER DRIER Connections on page 17 for special procedures on braz- ing filter drier connections to the liquid line. OUTDOOR UNIT FIGURE 6.
  • Page 16 LINE SET IMPORTANT — Refrigerant lines must not contact structure. INSTALLATION REFRIGERANT LINE SET — INSTALLING Line Set Isolation — The following illustrations are VERTICAL RUNS (NEW CONSTRUCTION SHOWN) examples of proper refrigerant line set isolation: NOTE — Insulate liquid line when it is routed through areas where the surrounding ambient temperature could become higher than the REFRIGERANT LINE SET —...

  • Page 17: Brazing Connections

    Polyol ester (POE) oils are used in to a pressurized system may result in ignition Lennox units charged with R-454B refrigerant. Residual of the refrigerant and oil mixture. Check the mineral oil can act as an insulator, preventing proper high and low pressures before applying heat.

  • Page 18: Cap And Core Removal

    CAP AND CORE REMOVAL CUT AND DEBUR Cut ends of the refrigerant lines square (free from nicks or dents) Remove service cap and core from and debur the ends. The pipe must remain round. Do not crimp end both the suction / vapor and liquid line of the line.

  • Page 19: Braze Line Set

    WRAP SERVICE VALVES To help protect service valve seals during brazing, wrap water-saturated cloths around service valve bodies and copper tube stubs. Use additional water-saturated cloths underneath the valve body to protect the base paint. FLOW NITROGEN Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration gauge set into the valve stem port connection on the liquid service valve and out of the suction / vapor valve stem port.

  • Page 20: Flushing Line Set And Indoor Coil

    Flushing Line Set and Indoor Coil TYPICAL EXISTING EXPANSION VALVE REMOVAL CONNECT GAUGES AND EQUIPMENT FOR PROCEDURE (UNCASED COIL SHOWN) FLUSHING PROCEDURE STUB END INVERTED CYLINDER GAUGE TWO PIECE PATCH PLATE LIQUID LINE CHECK CONTAINS CLEAN MANIFOLD (UNCASED COIL ONLY) ORIFICE EXPANSION HCFC22* TO BE USED...

  • Page 21: Installing Indoor Metering Device

    Installing Indoor Metering Device This outdoor unit is designed for use in systems that use The expansion valve unit must be installed inside the cab- an expan sion valve metering device (purchased separate- inet. In applications where an uncased coil is being in- ly) at the indoor coil.

  • Page 22: Leak Testing The System

    IMPORTANT Leak Testing the System The Environmental Protection Agency (EPA) prohibits IMPORTANT the intentional venting of HFC refrigerants during maintenance, service, repair and disposal of appliance. Leak detector must be capable of sensing A2L refrigerant. Approved methods of recovery, recycling or reclaiming must be followed.

  • Page 23: Evacuating Line Set And Indoor Coil

    Evacuating Line Set and Indoor Coil EVACUATION HIGH CONNECT GAUGE SET NOTE - Remove cores from service valves (if not already done). A - Connect low side of manifold gauge set with 1/4 SAE in-line tee to vapor line service valve B - Connect high side of manifold gauge set to OUTDOOR MANIFOLD...

  • Page 24: Electrical - Circuit Sizing And Wire Routing

    Use copper wire only with this product. corrode copper piping and compressor parts. WARNING Unit must be installed with Lennox approved refrigerant detection system (RDS) and sensor. Failure to use properly sized wiring and circuit breaker Do not operate system until refrigerant detection system is may result in property damage.
  • Page 25 ROUTING HIGH VOLTAGE, GROUND AND CONTROL WIRING HIGH VOLTAGE / GROUND WIRES WIRE RUN LENGTH AWG# INSULATION TYPE Any excess high voltage field wiring should be LESS THAN 100' (30 METERS) TEMPERATURE RATING trimmed and secured away from any low voltage field MORE THAN 100' (30 METERS) 16 35ºC MINIMUM.
  • Page 26 FIGURE 16. Typical Factory Wiring Diagram Page 26...

  • Page 27: Maintenance

    (less than 50psi). If the ture reaches 70° F. coil cannot be cleaned using water alone, Lennox recommends use of a coil cleaner with a pH in the range of 5 to 9. The coil must be rinsed thoroughly after cleaning.

  • Page 28: Start-Up And Performance Checklist

    Indoor Unit (Air Handler or Furnace) 8. Check for bearing/bushing wear on indoor blower mo- tor. Replace as necessary. 1. Inspect component wiring for loose, worn or damaged connections. Confirm proper voltage plus amperage in- 9. Indoor unit inspections of gas- or oil-fired furnaces will door unit.

  • Page 29: Typical Field Wiring

    RATING, INSULATION THICKNESS, AND TERMINATION. NOTE-MINIMUM TRANSFORMER REQUIRED IN INDOOR UNIT-40 VA LINE VOLTAGE FIELD INSTALLED CLASS II VOLTAGE FIELD WIRING DENOTES OPTIONAL COMPONENTS COOLING - LENNOX CONDENSING 2 STAGE AC Supersedes 2011 Litho U.S.A. FIGURE 17. Typical Field Wiring...

  • Page 30: Sequence Of Operations

    NOTE – The thermostat used may be electromechanical Unit Start-Up or electronic. IMPORTANT NOTE – Transformer in indoor unit supplies power (24 VAC) to the thermostat and outdoor unit controls. If unit is equipped with a crankcase heater, it should SEQUENCE OF OPERATIONS be energized 24 hours before unit start-up to prevent First and second stage cooling operate independent of...

  • Page 31: Indoor Coil

    MANIFOLD GAUGE SET HIGH GAUGE SET OUTDOOR UNIT CONNECTIONS FOR TESTING AND CHARGING REFRIGERANT TANK CHARGE IN LIQUID PHASE SUCTION LINE DIGITAL SCALE TO LIQUID TEMPERATURE SENSOR LINE SERVICE (LIQUID LINE) PORT TEMPERATURE SENSOR CLOSE MANIFOLD GAUGE SET VALVES AND CONNECT THE CENTER HOSE TO A CYLINDER OF R-454B SET FOR LIQUID PHASE CHARGING. CONNECT THE MANIFOLD GAUGE SET'S LOW PRESSURE SIDE TO THE SUCTION LINE SERVICE PORT.

  • Page 32: Decommissioning

    ML17KC2 unit is factory-charged with enough R-454B re- Charging frigerant to accommodate a 15-foot length of refrigerant piping. For line lengths over 15 feet, add 3 oz of refrigerant Verify the unit is electrically grounded before charging the for every 5 feet of piping beyond 15 feet. system.
  • Page 33 h) Do not overfill cylinders (no more than 80% volume liq- IMPORTANT uid charge). i) Do not exceed the maximum working pressure of the Equipment shall be labelled stating that it has been cylinder, even temporarily. decommissioned and emptied of refrigerant. The label shall be signed and dated.
  • Page 34 R‐454B Refrigerant Pressure‐Temperature Chart Saturated  Saturated  Saturated  Saturated  Saturated  Saturated  Saturated  Saturated  Pressure Pressure Pressure Pressure Liquid  Vapor  Liquid  Vapor  Liquid  Vapor  Liquid  Vapor  (psig) (psig) (psig) (psig) Temp (°F) Temp (°F) Temp (°F) Temp (°F) Temp (°F) Temp (°F) Temp (°F) Temp (°F) ‐58.9 ‐57.1 58.9 61.3 93.0 95.4 113.4 115.6 ‐19.2 ‐17.2...

  • Page 35: Start-Up Test Procedure

    4 - Press the Test button to terminate the simulated Start-Up Test Procedure Leak Detected mode upon test completion. The RDS Blower Control Board is equipped with a Test/ Heating Demand Reset button. After the RDS Blower Control Board has 1 - Prompt a heating demand at the thermostat.

  • Page 36: Important

    ML17KC2 Charging Procedures R454B CHARGING INFORMATION The unit is factory charged with the amount of R454B refrigerant indicated on the unit rating 3. Compare stabilized pressures with those provided in table 3, “Normal Operating Pres- plate. This charge is based on a matching indoor coil and outdoor coil with 15 feet (4.6 m) sures.”...

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