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 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.

 IMPORTANT

The Clean Air Act of 1990 bans the intentional venting of 

refrigerant (CFCs, HCFCs and HFCs) as of July 1, 1992. 

Approved methods of recovery, recycling or reclaiming 

must be followed. Fines and/or incarceration may be 

levied for noncompliance.

 IMPORTANT

This unit must be matched with an indoor coil as specified 

with  AHRI.  For  AHRI  Certified  system  matchups  and 

expanded ratings, visit www.LennoxPros.com. Coils 

previously charged with HCFC-22 must be flushed.

 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.

ML16XP1

Table of Contents

Installation Clearances ...................................................2

Model Number Identification

 ...........................................2

Dimensions .....................................................................3

Specifications

 .................................................................4

Typical Unit Parts Arrangement ......................................6

Operating Gauge Set and Service Valves ......................6

Unit Placement  ..............................................................8

Removing and Installing Louvered Panels .....................9

New or Replacement Line Set ......................................10

Brazing Connections  ...................................................12

Flushing Line Set and Indoor Coil ................................15

Installing Indoor Metering Device .................................16

Leak Test Line Set and Indoor Coil  ..............................17

Evacuating Line Set and Indoor Coil  ...........................18

Electrical .......................................................................19

System Operation   .......................................................21

System Configuration

 ...................................................21

Defrost System   ...........................................................24

Maintenance   ...............................................................26

Wiring and Sequence of Operation    ...........................28

Servicing Units Void of Charge   ...................................32

Start-Up   ......................................................................32

Service Literature

UNIT INFORMATION

Corp. 1818-L8 

March 3, 2020

ML16XP1 (HFC-410A) SERIES OUTDOOR UNITS

General Information 

These instructions are intended as a general guide and do 

not supersede national or local codes in any way. Consult 

authorities having jurisdiction before installation.
The Merit® ML16XP1 model is designed for use with 

HFC-410A refrigerant only. This unit must be installed with 

an approved indoor air handler or coil. For AHRI Certified 

system matchups and expanded ratings, visit www.Len-

noxPros.com.
This outdoor unit is designed for use in systems that use 

the following refrigerant metering device:
•  Check thermal expansion valve (CTXV)

IMPORTANT:

 Special procedures are required for clean-

ing the all-aluminum coil in this unit. See page 26 in this 

instruction for information.

Summary of Contents for ML16XP1 Series

Page 1: ...ay have multiple power supplies ML16XP1 Table of Contents Installation Clearances 2 Model Number Identification 2 Dimensions 3 Specifications 4 Typical Unit Parts Arrangement 6 Operating Gauge Set and Service Valves 6 Unit Placement 8 Removing and Installing Louvered Panels 9 New or Replacement Line Set 10 Brazing Connections 12 Flushing Line Set and Indoor Coil 15 Installing Indoor Metering Devic...

Page 2: ...des may be A clearance of 24 in must be maintained between two units 48 in 1219 mm clearance required on top of unit Model Number Identification Nominal Cooling Capacity 018 1 5 tons 024 2 tons 030 2 5 tons 036 3 tons 042 3 5 tons 048 4 tons 060 5 tons ML 16 X P 1 036 230 A 0 1 Nominal SEER Refrigerant Type X R 410A Revision Level Voltage 230 208 230V 1 phase 60hz Product Tier ML Merit Series Unit...

Page 3: ...6XP1 060 32 1 4 817 43 1 4 1099 42 1 2 1080 SUCTION AND C SIDE VIEW DISCHARGE AIR SIDE VIEW A B A LIQUID LINE CONNECTION OUTDOOR COIL FAN COMPRESSOR OPTIONAL UNIT STANDOFF KIT 4 FIELD INSTALLED 4 3 8 INLET AIR INLET AIR TOP VIEW INLET AIR INLET AIR SUCTION LINE CONNECTION LIQUID LINE CONNECTION 6 3 8 162 TOP VIEW BASE SECTION COMPRESSOR COIL DRAIN OUTLETS Around perimeter of base OPTIONAL UNIT STA...

Page 4: ... Power factor 0 98 0 98 0 96 0 99 Outdoor Fan Motor Full load amps 1 0 1 0 1 0 2 6 Locked rotor amps 1 9 1 9 1 9 OPTIONAL ACCESSORIES ORDER SEPARATELY iComfort M30 Smart Wi Fi Thermostat 15Z69 Remote Outdoor Temperature Sensor X2658 Compressor Crankcase Heater 94M04 93M05 Compressor Hard Start Kit LG 88M91 Compressor Sound Cover 69J03 Compressor Low Ambient Cut Off 45F08 Freezestat 3 8 in tubing 9...

Page 5: ... 0 99 0 99 0 99 Outdoor Fan Motor Full load amps 2 6 2 6 2 6 OPTIONAL ACCESSORIES ORDER SEPARATELY iComfort M30 Smart Wi Fi Thermostat 15Z69 Remote Outdoor Temperature Sensor X2658 Compressor Crankcase Heater 93M05 Compressor Hard Start Kit LG 88M91 Copeland 10J42 Compressor Sound Cover 69J03 Compressor Low Ambient Cut Off 45F08 Freezestat 3 8 in tubing 93G35 5 8 in tubing 50A93 Indoor Blower Off ...

Page 6: ...prevent stripping of the various caps used the appropriately sized wrench should be used and fitted snugly over the cap before tightening TABLE 1 Torque Requirements Parts Recommended Torque Service valve cap 8 ft lb 11 NM Sheet metal screws 16 ft lb 2 NM Machine screws 10 28 ft lb 3 NM Compressor bolts 90 in lb 10 NM Gauge port seal cap 8 ft lb 11 NM USING MANIFOLD GAUGE SET When checking the sys...

Page 7: ... 7 8 9 10 11 12 1 12 TURN To Access Service Port A service port cap protects the service port core from contamination and serves as the primary leak seal 1 Remove service port cap with an appropriately sized wrench 2 Connect gauge set to service port 3 When testing is completed replace service port cap and tighten as follows With torque wrench Finger tighten and torque cap per table 3 Without torq...

Page 8: ...ment of unit in relation to a window see the provided illustration in figure 3 detail A PLACING UNIT ON SLAB When installing unit at grade level the top of the slab should be high enough above grade so that water from higher ground will not collect around the unit The slab should have a slope tolerance as described in figure 3 detail B ROOF MOUNTING Install the unit a minimum of 6 inches 152 mm ab...

Page 9: ...ions that may cause panels to be blown around and battered WARNING REMOVAL STEP 1 INSERT PANEL UNDER UNIT TOP CAP LIP AND LIFT SLIGHTLY TO CLEAR SIDE LIP OF PANEL FROM BASE STEP 2 PANEL INSTALLATION TO REMOVE PANEL REMOVE MOUNTING SCREWS SECURING PANEL TO THE UNIT SLIGHTLY LIFT PANEL IN ORDER TO CLEAR SIDE LIPS OF PANEL FROM BASE OF UNIT STEP 3 TILT PANEL OUT SLIGHTLY AND PULL DOWNWARD TO REMOVE S...

Page 10: ...the amount of refrigerant charge in the system No need to add oil in system with 20 pounds of refrigerant or less For systems over 20 pounds add one ounce for every five pounds of refrigerant Recommended topping off POE oils are Mobil EAL ARC TIC 22 CC or ICI EMKARATE RL32CF MATCHING WITH NEW OR EXISTING INDOOR COIL AND LINE SET The RFC1 metering line consisted of a small bore copper line that ran...

Page 11: ... be used if line set is to be installed on exterior of outside wall PVC PIPE FIBERGLASS INSULATION CAULK OUTSIDE WALL VAPOR LINE WRAPPED WITH ARMAFLEX LIQUID LINE OUTSIDE WALL LIQUID LINE VAPOR LINE WOOD BLOCK BETWEEN STUDS STRAP WOOD BLOCK STRAP SLEEVE WIRE TIE WIRE TIE WIRE TIE INSIDE WALL REFRIGERANT LINE SET INSTALLING VERTICAL RUNS NEW CONSTRUCTION SHOWN INSTALLATION LINE SET NOTE Insulate li...

Page 12: ...rdous to your health Avoid breathing vapors or fumes from brazing operations Perform operations only in well ventilated areas Wear gloves and protective goggles or face shield to protect against burns Wash hands with soap and water after handling brazing alloys and flux IMPORTANT Allow braze joint to cool before removing the wet rag from the service valve Temperatures above 250ºF can damage valve ...

Page 13: ... SERVICE VALVE Flow regulated nitrogen at 1 to 2 psig through the low side refrigeration gauge set into the liquid line service port valve and out of the suction vapor line service port valve CUT AND DEBUR CAP AND CORE REMOVAL Cut ends of the refrigerant lines square free from nicks or dents and debur the ends The pipe must remain round Do not crimp end of the line Remove service cap and core from...

Page 14: ...ctions for the next step in preparing the unit WHEN BRAZING LINE SET TO SERVICE VALVES POINT FLAME AWAY FROM SERVICE VALVE PREPARATION FOR NEXT STEP 7 WARNING 1 FIRE PERSONAL INJURY OR PROPERTY DAMAGE may result if you do not wrap a water saturated cloth around both liquid and suction line service valve bodies and copper tube stub while brazing in the line set The braze when complete must be quenc...

Page 15: ...XISTING INDOOR UNIT GAUGE MANIFOLD INVERTED CYLINDER CONTAINS CLEAN HCFC22 TO BE USED FOR FLUSHING LIQUID LINE SERVICE VALVE INLET DISCHARGE TANK RETURN CLOSED OPENED RECOVERY CYLINDER RECOVERY MACHINE NEW OUTDOOR UNIT VAPOR LINE SERVICE VALVE VAPOR LIQUID 1 A Inverted HCFC 22 cylinder with clean refrigerant to the vapor service valve B HCFC 22 gauge set low side to the liquid line valve C HCFC 22...

Page 16: ...hreads and expose surface of the Teflon ring with refrigerantoil E Attach the liquid line assembly to the expansion valve Finger tighten and use an appropriately sized wrench to turn an additional 1 2 turn clockwise as illustrated in the figure above or 20 ft lb ON 7 8 AND LARGER LINES MOUNT SENSING BULB AT EITHER THE 4 OR 8 O CLOCK POSITION NEVER MOUNT ON BOTTOM OF LINE 12 ON LINES SMALLER THAN 7...

Page 17: ...closed connect the cylinder of HFC 410A refrigerant to the center port of the manifold gauge set Open the valve on the HFC 410A cylinder vapor only B Open the high pressure side of the manifold to allow HFC 410A into the line set and indoor unit Weigh in a trace amount of HFC 410A A trace amount is a maximum of two ounces 57 g refrigerant or three pounds 31 kPa pressure Close the valve on the HFC ...

Page 18: ...or unit until the absolute pressure does not rise above 500 microns 29 9 inches of mercury within a 20 minute period after shutting off the vacuum pump and closing the manifold gauge valves F When the absolute pressure requirement above has been met disconnect the manifold hose from the vacuum pump and connect it to an upright cylinder of HFC 410A refrigerant Open the manifold gauge valve 1 to 2 p...

Page 19: ...r to unit nameplate for minimum circuit ampacity and maximum overcurrent protection size 24VAC TRANSFORMER Use the transformer provided with the furnace or air han dler for low voltage control power 24VAC 40 VA mini mum 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 un...

Page 20: ...S TO PREVENT DAMAGE TO CONTROL SEE INSTALLATION INSTRUCTION FOR FURTHER DETAILS Typical Field Wiring Heat Pump Application with CBA38MV FIGURE 12 YELLOW BLUE NOT REQUIRED FOR SINGLE STAGE RED BLACK PURPLE PURPLE BLACK BLUE RED FAN RELAY NOT REQUIRED WITH SINGLE SPEED OUTDOOR FAN OUTDOOR SENSOR X2658 COMFORTSENSE 7500 THERMOSTAT OUTDOOR UNIT CUT ON BOARD LINK R O CUT ON BOARD LINK Y1 Y2 FOR TWO STA...

Page 21: ...ge pressure rises above the factory setting The switch is normally closed and is permanently adjusted to trip open at 590 15 psig 4068 103 kPa NOTE A Schrader core is under the pressure switches Crankcase Heater HR1 and Thermostat Switch S40 Certain units are equipped with a belly band type crank case heater HR1 prevents liquid from accumulating in the compressor The HR1 is controlled by a single ...

Page 22: ...T CONNECTIONS TEST PINS P1 Note Component locations vary by board manufacturer SENSOR CONNECTION COIL AND AMBIENT SENSORS P4 REVERSING VALVE O OUT DELAY PINS P5 LOW AMBIENT THERMOSTAT PINS P3 DEFROST TERMINATION PIN SETTINGS P1 Demand Defrost Control A108 FIGURE 14 Demand Defrost Control A108 ...

Page 23: ... of the defrost mode When a jumper is installed on the DELAY pins the compressor will be cycled off for 30 seconds going in and out of the defrost mode Units are shipped with jumper installed on DELAY pins NOTE The 30 second off cycle is NOT functional when TEST pins on P1 are jumpered P6 TST PS DF C R O Y1 Y2 Factory Test Connectors No field use DS1 RED LED Diagnostic LED Demand defrost control L...

Page 24: ...rature probe is de signed with a spring clip to allow mounting to the outside coil tubing The location of the coil sensor is important for proper defrost operation NOTE The demand defrost control accurately measures the performance of the system as frost accumulates on the outdoor coil This typically will translate into longer running time between defrost cycles as more frost accumulates on the ou...

Page 25: ...stem Remove any blockages or restrictions from coils and or fans Check indoor and outdoor fan motor for proper current draws Check system charge using subcooling method Check system operating pressures and compare to unit subcooling tables in this instruction or located on unit access panel Make sure all pressure switches and sensors have secure connections to system to prevent refrigerant leaks o...

Page 26: ...he outdoor unit s coil should be performed by a trained service technician Contact your dealer and set up a schedule preferably twice a year but at least once a year to inspect and service your outdoor unit The follow ing maintenance may be performed by the homeowner IMPORTANT After testing has been completed properly reposition test jumper across desired timing pins Maintenance DEALER WARNING Ele...

Page 27: ...ur dealer show you the location of the drain line and how to check for obstructions This would also apply to an auxiliary drain if installed Thermostat Operation See the thermostat homeowner manual for instructions on how to operate your thermostat Heat Pump Operation Your new Lennox heat pump has several characteristics that you should be aware of Heat pumps satisfy heating demand by delivering l...

Page 28: ...Page 28 Wiring and Sequence of Operation FIGURE 15 Typical Unit Wiring 018 thru 030 units ...

Page 29: ...Page 29 FIGURE 16 Typical Unit Wiring 036 thru 060 units ...

Page 30: ...Page 30 FIGURE 17 Typical Factory Wiring 018 thru 030 units ...

Page 31: ...Page 31 FIGURE 18 Typical Factory Wiring 036 thru 060 units ...

Page 32: ...demand cycle If the coil sensor temperature is still below the selected termination temperature the control will continue the defrost cycle until the cycle is terminated in one of the methods mentioned above If a defrost is ter minated by time and the coil temperature did not remain above 35 F 2 C for 4 minutes the control will go to the 30 minute Time Temperature mode Servicing Units Void of Char...

Page 33: ...mum Fuse or Circuit Breaker Electrical Connections Tight Indoor Filter clean Supply Voltage Unit Off Indoor Blower RPM S P Drop Over Indoor Dry Outdoor Coil Entering Air Temp Discharge Pressure Vapor Pressure Refrigerant Charge Checked Refrigerant Lines Leak Checked Properly Insulated Outdoor Fan Checked Service Valves Fully Opened Caps Tight Thermostat Voltage With Compressor Operating Calibrated...

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