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2010 Lennox Industries Inc.
Revised October 12, 2010
XC21
Service Literature
Corp. 1007−L2
XC21 (HFC−410A) SERIES UNITS
(non−icomfortt and icomfortt ENABLED)
THIS SERVICE MANUAL IS APPLICABLE TO BUILD
XC21−XXX−230−04 OR LATER.
NOTICE
A thermostat is not included and must be ordered
separately.
D The Lennox icomfort Touch thermostat must be used
in communicating applications.
D In non−communicating applications, the Lennox
ComfortSense
®
7000 thermostat may be used, as well
as other non−communicating thermostats.
In all cases, setup is critical to ensure proper system
operation.
Field wiring examples for non−communicating
applications begin on page 24.
See the icomfort Toucht thermostat Quick Start Guide
for communicating and partial communicating field wiring
connections.
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause personal injury, loss of life, or
damage to property.
Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.
Accessories
For update−to−date information, see any of the following
publications:
S Lennox XC21 Engineering Handbook
S Lennox Product Catalog
S Lennox Price Book
TABLE OF CONTENTS
Model Number Identification 2. . . . . . . . . . . . . . . . . . . .
Typical Serial Number Identification 2. . . . . . . . . . . . . .
Specifications 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Data 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Dimensions 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Parts Arrangement 5. . . . . . . . . . . . . . . . . . . . . . . .
Operating Gauge Set and Service Valves 6. . . . . . . . .
Unit Placement 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing and Installing Panels 11. . . . . . . . . . . . . . . . .
New or Replacement Line Set 12. . . . . . . . . . . . . . . . . .
Brazing Connections 14. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing the System 17. . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing the System 19. . . . . . . . . . . . . . . . . . . . . . .
Evacuating the System 21. . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Field Control Wiring 24. . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Conditioner Control (A175) Jumpers
and Terminals 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Refrigerant 27. . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating and Temperature Pressures 31. . . . . . . . . .
System Operations 32. . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Status, Fault and Lockout LED Codes 36. . . .
Component Field Configuration and
Troubleshooting 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SunSource
®
Home Energy System 50. . . . . . . . . . . . . .
Checklists 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Wiring Diagrams 52. . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Sequence of Operations 54. . . . . . . . . . . . . . . . . . .
The XC21 is a high efficiency residential split−system air
conditioner unit, which features a one−stage scroll
compressor, icomfortt control and HFC−410A refrigerant.
Units are available in 2, 3, 4 and 5−ton sizes. This model
series is designed for use with an expansion valve
metering device only. Refer to the XC17 Engineering
Handbook for ordering the correct indoor coil expansion
valve.
This model is also SunSourcet ready beginning with
XC21−XXX−230−05 build.
This document provides information only on build
XC21−XXX−230−04 and later which features the new air
conditioner control hardware and other enhancements.
Refer to Corp. 0504−L2 for earlier model version service
related information.
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