Lennox ML193UH045P36B

Page 1
© 2014 Lennox Industries Inc.
Litho U.S.A.
Corp. 1025-L5
ML193UH
Service Literature
Revised 03-2014
ML193UH SERIES UNITS
ML193UH series units are high-efficiency gas furnaces
manufactured with Lennox DuralokPlust aluminized steel
clamshell-type heat exchangers, with a stainless steel con
densing coil. ML193UH units are available in heating input
capacities of 44,000 to 132,000 Btuh (13 to 38.6 kW) and
cooling applications from 2 through 5 tons (7.0 through
17.6 kW). Refer to Engineering Handbook for proper siz
ing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LPG operation. All ML193UH
units are equipped with a hot surface ignition system. The
gas valve is redundant to assure safety shut-off as required
by C.S.A.
The heat exchanger, burners and manifold assembly can
be removed for inspection and service. The maintenance
section gives a detailed description on how this is done.
All specifications are subject to change. Procedures out
lined in this manual are presented as a recommendation
only and do not supersede or replace local or state codes.
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon
nect switch(es). Unit may have multiple
power supplies.
Table of Contents
Specifications 2.................................
Optional Accessories 3..........................
Blower Performance Data 4......................
I-Unit Components 7............................
II Placement and Installation 19....................
III-Start-Up 40...................................
IV-Heating System Service Checks 41..............
V-Typical Operating Conditions 43.................
VI-Maintenance 44...............................
VII-Sequence of Operation and Flow Charts 47......
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person
al injury or loss of life. Installation and service must
be performed by a licensed professional HVAC in
staller (or equivalent), service agency or the gas sup
plier.
WARNING
Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.

Lennox ML193UH045P36B Specifications

General

Brand	Lennox
Model	ML193UH045P36B
Category	Furnace
Language	English

Summary

Unit Information and Safety

Critical Safety Warnings

Critical safety warnings for electrical shock, installation, and sharp edges.

Unit Component Identification

ML193 UH Parts Diagram

Diagram showing major components of the ML193UH unit.

Unit Components Details

Control Box Components and Diagrams

Details of transformer, interlock switch, ignition control, and terminal designations.

Safety and ESD Precautions

Critical safety warnings and ESD precautions for servicing controls.

Integrated Control System

Control System Operation and Settings

Fan control adjustments, terminal designations, and system operation overview.

Diagnostic Codes and Sequence

Diagnostic Codes and Timing Diagrams

Table of diagnostic codes and sequence of operation timing diagram.

Integrated Ignition Control Details

Ignition Control Operation and Safety

Electronic ignition process, safety warnings, and terminal designations.

Diagnostic Codes and Tables

Table of diagnostic codes and terminal designations for troubleshooting.

Integrated Control Diagrams

Control Wiring and Ignition Sequence

Wiring diagram for the integrated control and its electronic ignition sequence.

Heating Components

Burner Box Components and Safety

Details on ignitor, flame sensor, rollout switches, and burner box assembly diagram.

Ignitor Checks and Specifications

Ignitor Testing Procedures and Tables

Procedures and tables for checking ignitor resistance and voltage.

Component Details

Limit, Heat Exchanger, Burners, and Gas Valve

Info on limit control, heat exchanger, burners, orifices, and gas valve.

Combustion Air System Components

Inducer, Header Box, and Pressure Switch

Details on inducer, header box, pressure switch, and orifice sizes.

Pressure Measurement and Blower Compartment

Pressure Differential Measurement and Blower Components

Procedures for measuring pressure differential and accessing blower components.

Installation Cautions and Vent Termination Guidelines

Confined Space Installation Cautions and Vent Termination Guidelines

Cautions for confined spaces and general guidelines for vent terminations, including important notes.

Condensate Trap and Drain Components

Condensate Trap Locations and Drain Components

Diagrams showing condensate trap locations and field-provided drain components.

Trap and Drain Assembly Diagrams (34 Connection)

TrapDrain Assembly Diagrams (34 Connection)

Detailed diagrams for trap and drain assemblies using 3/4" PVC piping.

Trap and Drain Assembly Diagrams (12 Connection)

TrapDrain Assembly Diagrams (12 Connection)

Start-Up Procedures

Preliminary Checks, Heating Start-Up, and Gas Valve Operation

Heating System Service Checks

Gas Piping, Pressure Testing, and Combustion Analysis

Combustion Analysis and Altitude Adjustments

Combustion Analysis Data and Altitude Requirements

Maintenance Procedures

Blower, Filter, Pipe Checks, Electrical, and Condensate Care

Heat Exchanger Cleaning

Heat Exchanger Cleaning Procedure

Burner Assembly Cleaning

Burner Assembly Cleaning Procedure

Wiring Diagram and Sequence of Operation

ML193 UH Wiring Diagram and Heating Sequence Steps

Heating Sequence Flow Chart (Control 100973)

Heating Sequence Continued

Normal and Abnormal Heating Mode Flow Chart Details

Cooling Sequence of Operation

Normal and Abnormal Cooling Mode Flow Charts

ML193 UH Wiring Diagram (Control 103085)

Blower Speed, Jack Plugs, and Heating Sequence Steps

Heating Sequence Flow Chart (Control 103085)

Normal and Abnormal Heating Mode Flow Charts