Lennox MS8 SERIES

Page 1
2015 Lennox Industries Inc.
Corp. 1244-L9
Revised January 12, 2015
MS8 SERIES
INSTALLATION AND SERVICE
PROCEDURES
MS8 SERIES UNITS — MINI-SPLIT SINGLE-ZONE SYSTEMS (208-230V)
MS8-CO Air Conditioner Outdoor Unit
MS8-HO Heat Pump Outdoor Unit
MS8-CI Air Conditioner Indoor Unit
MS8-HI Heat Pump Indoor Unit
Wireless
Remote Control
(furnished)
CAUTION
Physical contact with metal edges and corners while
applying excessive force or rapid motion can result in
personal injury. Be aware of, and use caution when
working near these areas during installation or while
servicing this equipment.
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.
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
These units must be installed as a matched system as
specified in the Lennox Engineering Handbook.
TABLE OF CONTENTS
I. OVERVIEW
Shipping and Packing List 2......................
Required Tools and Supplies 3....................
Specifications 4.................................
Model Number Identification 6....................
Unit Dimensions and Weights 6...................
Typical System Component Setup 6...............
II. INSTALLATION
General 8......................................
Clearances 8...................................
Torque Requirements for Caps and Fasteners 8....
Setting Outdoor Unit 8...........................
Repositioning Indoor Air Temperature Sensor 10.....
Indoor Unit Placement and Preparation 10..........
Indoor Unit Cable Connections 14..................
Securing Indoor Unit to Wall Mounting Bracket 15....
Outdoor Unit Cable Connections 16................
Operating Service Valves 19.......................
Line Set Requirements 20.........................
Leak Test and Evacuation 22......................
Unit Start-Up 23.................................
Adding Refrigerant for Longer Line Sets 23..........
Checking Large Line Operating Pressures 23........
Wrapping Bundle 25..............................
Maintenance 26....................................
III. OPERATING THE WIRELESS REMOTE
IV. SYSTEM OPERATION AND SERVICE
System Operational Modes 35.......................
System Functions 43...............................
System Protection Features 44......................
Other Functions 46.................................
Temperature Sensors (location, function and
troubleshooting 47.................................
Indoor and Outdoor Control Parts Identifications 53.....
Indoor and Outdoor Error Codes 57..................
Refrigerant System Flow Diagrams 66................
Typical Unit Wiring Diagrams 67...................
Troubleshooting 72.................................
Major System Components 81.......................
Optional Condensate Pump Wiring Connection 88...........
Disassembly Procedures 88.........................

Lennox MS8 SERIES Specifications

General

Category	Air Conditioner
Manufacturer	Lennox
Refrigerant	R-410A
Cooling Stages	Single Stage
Cooling Capacity	1.5 - 5 Ton
Compressor Type	Scroll Compressor
Coil	Aluminum Coil
Product Series	MS8 SERIES

Summary

Overview

Required Tools and Supplies

Specifications

Installation

Important Installer Information

Clearances

Specifies minimum installation clearances required around the units.

Torque Requirements for Caps and Fasteners

Operating the Wireless Remote

Wireless Remote Functions

Overview of the functions available on the wireless remote.

System Operation and Service

Setting Outdoor Unit

Outdoor Unit Positioning Considerations

Indoor Unit Placement and Preparation

Indoor Unit Location

Securing Wall Mounting Bracket to Wall

Indoor Unit Cable Connections

Securing Indoor Unit to Wall Mounting Bracket

Secure Indoor Unit to Wall Mounting Bracket

Outdoor Unit Wiring Connections

Wiring Connections

Outdoor Unit Electrical Connections

Operating Service Valves

Line Set Requirements

Line Set Installation

Line Set Length and Elevation

Connecting Line Set Between Indoor and Outdoor Units

Leak Test and Evacuation

Leak Test

Steps for performing a leak test on the system.

Evacuation

Unit Start-Up

Adding Refrigerant for Longer Line Set

Checking Large Line Operating Pressures

Manifold Gauge Set Connections

Using HFC-410 A Weigh-In Method

Maintenance

Outdoor Unit

Maintenance tasks specific to the outdoor unit.

Indoor Unit

Maintenance tasks specific to the indoor unit.

System Start Up Using Wireless Remote

General Operation

General steps for operating the system via the remote.

Special Functions

Homeowner Maintenance

System Operational Modes

AUTO MODE

Details on how the AUTO mode functions.

Protective Functions

Auto Cool

Auto Heat

Cooling Mode (I FEEL Mode Off)

Cooling Mode (I FEEL Mode On)

I FEEL Mode

How the I FEEL mode affects system operation.

Indoor Fan Operation - Cooling

Dehumidification Mode (I FEEL Mode Off)

Dehumidification Mode (I FEEL Mode On)

Cool ON

Cooling activation conditions with I FEEL mode.

Cool OFF

Cooling deactivation conditions with I FEEL mode.

Indoor Fan Operation - Dehumidification

FAN MODE

Heat Mode (I FEEL Mode Off)

Heat Mode (I FEEL Mode On)

Heat ON

Heating activation conditions with I FEEL mode.

Heat OFF

Heating deactivation conditions with I FEEL mode.

Indoor Fan Operation - Heating

Reversing Valve Operation

Defrost Mode (Heat Pump Only)

Defrost Initiation

Conditions that trigger the defrost cycle.

Defrost Termination

Conditions that terminate the defrost cycle.

Cold Blow Prevention

System Functions

SLEEP

Details the Sleep function for temperature management.

TURBO

Explains the Turbo function for accelerated heating or cooling.

System Protection Features

COMPRESSOR PROTECTION

Protection mechanisms for the compressor.

INDOOR COIL FREEZE PROTECTION

How the system prevents the indoor coil from freezing.

Intelligent Power Module (IPM) Protection

Power Factor Correction (PFC) Protection

Compressor Over-Current Protection

Compressor Over-Load Protection

Outdoor Coil High Temperature Protection

Communication Fault (E6)

Outdoor Unit Control Protection

Other Functions

System Refrigerant Recovery Function

Procedure to recover refrigerant into the outdoor unit.

Indoor Mode Conflict Protection (E7)

Temperature Sensors

Discharge Line Temperature Sensor (RT5)

DISCHARGE LINE TEMPERATURE PROTECTION SEQUENCE (RT5)

How discharge line temperature affects operation.

Temperature Sensor Faults

Testing Temperature Sensor Resistances

Indoor and Outdoor Ambient Sensor Resistance Values (15 K)

Indoor and Outdoor Coil Sensor Resistance Values (20 K)

Outdoor Discharge Line Sensor Resistance Values (50 K)

System Temperature Sensors

INDOOR UNIT

Identification of indoor unit sensors.

OUTDOOR UNIT

Identification of outdoor unit sensors.

Indoor and Outdoor Control Parts Identification

INDOOR CONTROLS

Identification of parts on indoor unit control boards.

Typical Indoor Unit Control

Typical 30 kBtu Indoor Unit Control

Outdoor Controls

Typical 9-12 kBtu Outdoor Controls

Diagram and labels for 9-12 kBtu outdoor control boards.

Typical 18 - 24 kBtu Outdoor Controls

Diagram and labels for 18-24 kBtu outdoor control boards.

Typical 30 kBtu Outdoor Controls

Indoor and Outdoor Error Codes

INDOOR UNIT FRONT PANEL INDICATORS

Indicators on the indoor unit's front panel.

System Status and Error Codes (09, 12, 30 kBtu)

SYSTEM STATUS LEDS

SYSTEM ERROR DISPLAY AND LEDS

Explains error codes and associated LED indicators.

System Status and Error Codes (09, 12, 30 kBtu) - Continued

System Status and Error Codes (18-24 kBtu)

System Status and Error Codes (18-24 kBtu) - Continued

Refrigerant System Flow Diagrams

TYPICAL AIR CONDITIONER SYSTEM

Diagram showing refrigerant flow in an AC system.

TYPICAL HEAT PUMP SYSTEM

Diagram showing refrigerant flow in a heat pump system.

Typical Unit Wiring Diagrams

TYPICAL INDOOR UNIT WIRING DIAGRAM - 09 THROUGH 18 KBTU SYSTEMS (208 230 V)

Wiring diagram for 09-18 kBtu indoor units.

Typical Indoor Unit Wiring Diagram (24 kBtu)

Typical Indoor Unit Wiring Diagram (30 kBtu)

Typical Outdoor Unit Wiring Diagram (09 & 12 kBtu Heat Pump)

Typical Outdoor Unit Wiring Diagram (18 kBtu AC)

Typical Outdoor Unit Wiring Diagram (18 kBtu Heat Pump)

Typical Outdoor Unit Wiring Diagram (24 kBtu AC)

Typical Outdoor Unit Wiring Diagram (24 kBtu Heat Pump)

Typical Outdoor Unit Wiring Diagram (30 kBtu Heat Pump)

Troubleshooting

SYSTEM FAILED START UP (ALL SIZES)

Steps to troubleshoot when the system fails to start.

Poor System Operation

Refrigerant flow issue.

Insufficient air flow

Poor System Operation (Continued)

Indoor fan is not running.

The compressor is running but the outdoor fan is off.

The compressor is not running, however the outdoor fan is on.

The compressor is running hot and the overload protection feature is cycling compressor off.

Heat Pump Failed Start Up

Compressor will not start in either heating or cooling modes.

Indoor unit leaking water.

Abnormal sound or vibration.

Capacitor Charge Fault (Outdoor Unit)

Outdoor Unit High Temperature and Overload Protection

Outdoor Unit Overload and Discharge Line Sensor Malfunction

Outdoor Power Factor Correction Fault

Inter-Unit Communication Error

Major System Components

Component: Indoor Fan Motor

Details the indoor fan motor's function and troubleshooting.

Component: Indoor Louver Motor (Swing Motor)

Details the indoor louver motor's function and troubleshooting.

Component: Outdoor Fan Motor

Component: Rotary Compressor with Accumulator

Component: Compressor Temperature Overload Protection

Component: Electronic Expansion Valve

Component: Reversing Valve (Heat Pump Only)

Component: IndoorOutdoor Communication Line

Disassembly Units

Indoor Unit Front Case Removal

Removing Air Filter and Front Panel

Outdoor Unit Dis-Assembly

1. Remove the top cover and front-side plates.

2. Remove exhaust grille

Remove Right-Side Panel

Remove Electric Box

Remove Left-Side Plate

Remove Motor and Motor Support

Remove Reversing Valve

Remove 2-Way Shutoff and 3-Way Service Valves

Remove Compressor Assembly

Remove Isolation Sheet

Remove Coil Support Plate

Remove Chassis and Coil