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Service Literature
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
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
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.
CAUTION
Servicing shall be performed only as recommended by
the manufacturer.
UNIT INFORMATION
ML14KP1 (R-454B) SERIES OUTDOOR UNITS
100108
February 24, 2025
Table of Contents
Installation Clearances ...................................................6
Model Number Identification ...........................................7
Dimensions .....................................................................8
Specifications .................................................................9
Typical Unit Parts Arrangement .................................... 11
Operating Gauge Set and Service Valves .................... 11
Unit Placement ............................................................13
Removing and Installing Louvered Panels ...................14
New or Replacement Line Set ......................................15
Brazing Connections ...................................................17
Flushing Line Set and Indoor Coil ................................20
Installing Indoor Metering Device .................................21
Leak Test Line Set and Indoor Coil ..............................22
Evacuating Line Set and Indoor Coil ...........................23
Electrical .......................................................................24
System Operation .......................................................25
Charging ......................................................................26
System Configuration ...................................................26
Defrost System ...........................................................29
Maintenance ...............................................................32
Servicing Units Void of Charge ...................................36
Start-Up ......................................................................36
Decommissioning ........................................................37
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® ML14KP1 model 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 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 30 in this
instruction for information.
NOTE - This unit ML14KP1 is a PARTIAL UNIT AIR CON-
DITIONER, complying with PARTIAL UNIT requirements
of this Standard, and must only be connected to other
units that have been confirmed as complying to corre-
sponding PARTIAL UNIT requirements of this Standard,
UL 60335-2-40/CSA C22.2 No. 60335-2-40, or UL 1995/
CSA C22.2 No 236.
Page 1
ML14KP1
...........................34
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Table of Contents
Related Manuals for Lennox ML14KP1-036
Summarization of Contents
Typical Unit Parts Arrangement
Operating Gauge Set and Service Valves
Details torque requirements and usage of gauge sets and service valves.
Service Valves Angle and Ball
Operating Angle Type Service Valve
Explains the operation and steps for angle-type service valves.
Operating Ball Type Service Valve
Explains the operation and steps for ball-type service valves.
To Access Service Port
Describes how to access and reconnect service ports for testing.
Unit Placement
Positioning Considerations
Factors to consider when positioning the unit for optimal performance and sound.
Placing Unit on Slab
Guidelines for properly mounting the unit on a slab.
Roof Mounting
Instructions and considerations for installing the unit on a roof.
New or Replacement Line Set
Refrigerant Line Set
Information on selecting and sizing refrigerant lines for installation.
Line Set Isolation
Methods for isolating refrigerant lines to prevent vibration and noise.
Brazing Connections
Brazing Procedures
Step-by-step guide for brazing refrigerant line set connections to service valves.
Installing Indoor Metering Device
Indoor Expansion Valve Installation
Instructions for installing the expansion valve at the indoor coil.
Sensing Bulb Installation
Guidelines for correctly positioning and installing the sensing bulb.
Equalizer Line Installation
Steps for connecting the equalizer line to the expansion valve.
Electrical
24VAC Transformer
Specifies the transformer requirements for low-voltage control power.
Install Thermostat
Guidelines for selecting the proper location for thermostat installation.
System Operation
Unit Components
Overview of key components within the system and their functions.
Charging
System Configuration
Details on system setup, including defrost control and configurations.
Defrost System
Emergency Heat
Explains the function and usage of emergency heat mode.
Defrost System Overview
General explanation of how the defrost system monitors and operates.
Defrost Cycle Actuation
How defrost cycles are initiated based on system conditions.
Demand Defrost Operation
Detailed description of the demand defrost algorithm and operation.
Frost Accumulation Time
Explanation of how frost accumulation time affects defrost cycles.
Cold Climate Defrost
Specific defrost operation adjustments for cold weather conditions.
Defrost Control Connections, Jumpers Settings and Features
Information on connecting, setting up, and features of the defrost control.
Maintenance
Outdoor Unit
Procedures for inspecting and cleaning the outdoor unit's coil and components.
Indoor Unit
Maintenance tasks for the indoor unit, including filters and blowers.
Homeowner
Recommended maintenance tasks for homeowners to perform.
ML14KP1 Operating Sequence
Servicing Units Void of Charge
Procedures for servicing the unit when it is void of refrigerant.
Start-Up
Steps for starting up the unit after installation or servicing.
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