Lennox XC21 Series User Manual

Page 31
XC21
Operating and Temperature Pressures
Minor variations in these pressures may be expected due to differences in installations. Significant differences could mean
that the system is not properly charged or that a problem exists with some component in the system.
IMPORTANT
Use this table to perform maintenance checks; it is not a procedure for charging the
system. Minor variations in these pressures may be due to differences in installations.
Significant deviations could mean that the system is not properly charged or that a
problem exists with some component in the system.
Table 4. Normal Operating Pressures (Liquid +10 and Suction +5 psig)* (−04 build)
XC21−XXX−230−04 Only
−024 −036 −048 −060
5F (5C)** Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor
First Stage (Low Capacity)
65 (18.3) 208 143 214 146 216 142 232 137
75 (23.9) 242 145 247 149 246 144 269 138
85 (29.4) 278 147 288 151 288 146 310 140
95 (35.0) 323 150 333 154 336 147 357 144
105 (40.6) 367 153 383 155 385 149 405 145
115 (46.1) 421 155 441 156 444 153 459 149
Second Stage (High Capacity)
65 (18.3) 209 139 218 141 220 137 236 138
75 (23.9) 242 140 252 141 254 139 281 133
85 (29.4) 274 142 294 144 297 141 323 135
95 (35.0) 325 145 339 147 344 144 370 138
105 (40.6) 373 147 389 150 394 144 421 141
115 (46.1) 419 149 447 152 452 147 476 144
XC21−XXX−230−05 and later
First Stage (Low Capacity)
65 (18.3) 209 144 211 142 215 140 229 134
75 (23.9) 242 145 244 144 250 142 264 137
85 (29.4) 281 146 285 146 288 144 306 140
95 (35.0) 324 148 330 149 338 146 353 144
105 (40.6) 372 151 380 151 387 149 405 146
115 (46.1) 426 152 436 154 459 152 468 146
Second Stage (High Capacity)
65 (18.3) 213 138 214 137 217 124 238 130
75 (23.9) 245 142 247 140 251 133 276 133
85 (29.4) 285 142 288 141 289 138 317 135
95 (35.0) 329 144 330 143 336 141 368 139
105 (40.6) 376 147 384 145 385 144 420 141
115 (46.1) 432 151 445 148 437 146 478 143
* Typical pressures only, expressed in psig (liquid +/− 10 and vapor+/− 5 psig); indoor match up, indoor air quality, and indoor load will cause the
pressures to vary. These operating pressures are also listed on the unit charging sticker (401104S) located on the unit access panel.
** Temperature of air entering outdoor coil.

Lennox XC21 Series Specifications

General

SEER Rating	Up to 21.00
Sound Rating	As low as 69 dB
Energy Star Certified	Yes
Refrigerant	R-410A
Cooling Capacity	2 to 5 tons
Warranty	10-year limited warranty on compressor and covered components

Summary

Electrical Data

Operating Gauge Set and Service Valves

TORQUE REQUIREMENTS

SERVICE VALVES ANGLE AND BALL

Unit Placement

PLACING UNIT ON SLAB

ELEVATING THE UNIT

STABILIZING UNIT ON UNEVEN SURFACES

ROOF MOUNTING

New or Replacement Line Set

REFRIGERANT LINE SET

Information on installation or replacement of existing refrigerant line sets.

Brazing Connections

Flushing the System

TYPICAL FIXED ORIFICE REMOVAL PROCEDURE

TYPICAL CHECK EXPANSION VALVE REMOVAL PROCEDURE

CONNECT GAUGES AND EQUIPMENT FOR FLUSHING PROCEDURE

Procedure for connecting gauges and equipment for the flushing process.

FLUSHING LINE SET

Detailed procedure for flushing the line set and indoor unit coil.

TYPICAL CHECK EXPANSION VALVE INSTALLATION PROCEDURE

Leak Testing the System

IMPORTANT

Notes regarding leak detection capability for HFC refrigerants and EPA regulations.

CONNECT GAUGE SET

TEST FOR LEAKS

Evacuating the System

CONNECT GAUGE SET

Steps for connecting the gauge set for system evacuation.

EVACUATE THE SYSTEM

Procedure to evacuate the line set and indoor unit to a specific vacuum level.

Electrical

SIZE CIRCUIT AND INSTALL DISCONNECT SWITCH

Guidelines for sizing circuits, installing disconnect switches, and wiring.

INSTALL THERMOSTAT

Instructions for installing the room thermostat at the recommended height and location.

Field Control Wiring

ComfortSense® 7000 Thermostats - Non-Communicating Connections - Furnace/Two-Stage Air Conditioner

Air Conditioner Control (A175) Jumpers and Terminals

Unit Start-Up

GAUGE SET CONNECTIONS FOR TESTING AND CHARGING

Procedures for connecting the gauge set for system testing and charging.

System Refrigerant

ADDING OR REMOVING REFRIGERANT

AIRFLOW

INDOOR COIL

WEIGH IN

CALCULATING SYSTEM CHARGE FOR OUTDOOR UNIT VOID OF CHARGE

Method for calculating total refrigerant charge when the system is void of refrigerant.

APPROACH

SUBCOOLING

TEST AND CHARGE METHOD

Procedure for testing and charging the system using the subcooling method.

Operating and Temperature Pressures

Table 4. Normal Operating Pressures

System Operation

COMPRESSOR ANTI-SHORT CYCLE DELAY

Explanation of the compressor's anti-short cycle delay function.

HIGH (S4) AND LOW (S87) PRESSURE SWITCHES

Description of the high and low pressure switches and their operation.

HIGH DISCHARGE LINE TEMPERATURE SENSOR (RT28)

Details on the high discharge line temperature sensor and its fault conditions.

OUTDOOR AMBIENT TEMPERATURE (RT13)

E33 JUMPER (TEST) PINS

System Status, Fault and Lockout LED Codes

DS11 AND DS14 - SYSTEM STATUS, FAULT AND LOCKOUT LED CODES

Explanation of LED codes indicating system status, faults, and lockouts.

DS15 AND DS13 - COMPRESSOR FAULT AND LOCKOUT LED CODES

Explanation of LED codes indicating compressor faults and lockouts.

RESETTING LED FAULT AND LOCKOUT LED CODES

System fault and lockout LED (DS11 / DS14) alarm codes

Field Configuration and Testing

Verifying Correct DC Output Voltage (J2)

VERIFYING CORRECT INPUT VOLTAGE (ECM/Y1, ECM/Y2, ECM C AND EXT ECM/R)

Figure 21. Fan Motor Control One/Two Stage and EDA LED Sequence of Operation

Figure 22. Fan Control, Wiring, Jumper Settings, Testing and LED Location

Figure 23. Testing for External Power to Fan Motor Control

Fan Motor (B4) Test Procedure

FAN MOTOR TEST

AIR CONDITIONER CONTROL (A175) UNIT NOMINAL CAPACITY CODE CONFIGURATION

Figure 26. Main Control (A175) Unit Nominal Capacity Code Configuration

Illustrates the process for configuring the unit's nominal capacity code via LEDs.

Maintenance

OUTDOOR UNIT MAINTENANCE

INDOOR UNIT MAINTENANCE

Start-Up and Performance Checklist

START UP CHECKS

COOLING MODE

Unit Wiring Diagrams

Figure 28. Typical XC21 Wiring (non-icomfort™ enabled (XC21-XXX-230-04 build)

Figure 29. Typical XC21 Wiring (with icomfort™ enabled, Surge Protection and Fan Motor Control (A177) Rewired) (XC21-XXX-230-05 build)

Figure 30. Typical XC21 Wiring (with icomfort™ enabled, New Fan Motor with built-in surge protection and External Surge Protection Device Removed (XC21-XXX-230-06 build)

Unit Sequence of Operations

Figure 31. One-Stage and Two-Stage Cooling Sequence of Operation

Figure 32. Low Pressure (S87) Switch Sequence of Operation

Figure 33. High Pressure (S4) Switch Sequence of Operation

Figure 34. High Discharge Temperature (RT28) Sensor Sequence of Operation