Lennox 13ACC Series - User Manual

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2002 Lennox Industries Inc.

Corp. 0219−L5

13ACC

Service Literature

13ACC SERIES UNITS

The 13ACC is a residential splitsystem condensing unit

with SEER ratings up to 14.80. The series is designed for

use with expansion valves (TXV) and RFC. All 13ACC units

utilize scroll compressors.

13ACC condensing units are available in 2, 2 1/2, 3, 3 1/2, 4

and 5 ton capacities. All major components (indoor blower

and coil) must be matched according to Lennox recommen

dations for the compressor to be covered under warranty.

Refer to the Engineering Handbook for approved system

matchups.

Information contained in this manual is intended for use by

qualified service technicians only. All specifications are subject

to change.

This manual is divided into sections which discuss the

major components, refrigerant system, charging proce

dure, maintenance and operation sequence.

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 qualified installer or service

agency.

WARNING

Refrigerant can be harmful if it is inhaled. Refrigerant

must be used and recovered responsibly.

Failure to follow this warning may result in person

al injury or death.

TABLE OF CONTENTS

General 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specifications 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Data 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I Unit Components 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

II Refrigerant System 6. . . . . . . . . . . . . . . . . . . . . . . . . . .

III Charging 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV Maintenance 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

V Wiring and Operating Sequence 12. . . . . . . . . . . . . . .

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

CAUTION

Electrostatic discharge can affect electronic

components. Take precautions during unit instal

lation and service to protect the unit’s electronic

controls. Precautions will help to avoid control

exposure to electrostatic discharge by putting

the unit, the control and the technician at the

same electrostatic potential. Neutralize electro

static charge by touching hand and all tools on an

unpainted unit surface before performing any

service procedure.

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Summary

Unit Components

Compressor Contactor K1

The compressor is energized by a contactor located in the control box. Single-pole contactors are used in 13ACC series units.

A - Control Box

13ACC units are not equipped with a 24V transformer. All 24 VAC controls are powered by the indoor unit. Refer to wiring diagram.

DANGER

Warning about single-pole contactors and electrical shock hazard. Unit must be grounded.

Timed Off Control TOC (option)

Refrigerant System

Plumbing

Field refrigerant piping consists of liquid and suction lines from the condensing unit to the indoor evaporator coil. Use Lennox L15 series.

DANGER

Warning against backseat valve operation to prevent snap ring explosion and injury.

Charging

Pumping Down System

Procedure for pumping down the system for leak checking or repairs, warning against deep vacuum operation.

Leak Testing

Procedure for leak testing the line set and indoor coil using dry nitrogen, with safety precautions.

Charging

Weighing in the Charge

Procedure for weighing refrigerant charge into the unit for fixed orifice or TXV systems based on outdoor temp.

Charging Using the Approach Method

Charging Using the Subcooling Method

Maintenance

Outdoor Unit

Instructions for cleaning and inspecting the outdoor unit, condenser coil, and lines.

Indoor Coil

Instructions for cleaning the indoor coil and checking connecting lines for oil leaks.

Indoor Unit

Instructions for cleaning/changing filters, checking wiring, voltage, and amp-draw on blower motor.

Wiring Diagrams and Sequence of Operation

The Lennox 13ACC is a residential split-system condensing unit designed for cooling applications. It boasts SEER ratings up to 14.80, indicating high energy efficiency. The unit is designed for use with both expansion valves (TXV) and fixed orifice (RFC) systems, offering flexibility in installation. All 13ACC units are equipped with scroll compressors, known for their efficiency and reliability.

Technical Specifications and Capacities:

The 13ACC series is available in a range of capacities to suit various residential needs, specifically 2, 2-1/2, 3, 3-1/2, 4, and 5 tons.

Refrigerant: The units are factory-charged with HCFC-22 refrigerant. The charge amount varies by model and is sufficient for a 20 ft (6.1 m) line set. Adjustments are necessary for different line set lengths.
Electrical Data: The units operate on 208/230V, 60Hz, single-phase power. Minimum circuit ampacity ranges from 14.0A for the 2-ton unit (13ACC-024) to 38.0A for the 5-ton unit (13ACC-060). Recommended maximum fuse sizes range from 20A to 60A.
Compressor: Scroll compressors are used across the series. Rated load amps vary from 10.3A (13ACC-024) to 28.9A (13ACC-060), with corresponding locked rotor amps from 56.0A to 169.0A. Power factor is consistently high, ranging from 0.94 to 0.98.
Condenser Fan Motor: Full load amps for the condenser fan motor range from 1.1A to 1.9A, and locked rotor amps from 1.9A to 4.1A, depending on the model. Fan diameters are typically 18 inches (457 mm) or 22 inches (559 mm), with 3 or 4 blades.
Connections: Liquid line connections are 3/8 inch (9.5 mm) o.d. for all models. Suction line o.d. varies by capacity, from 3/4 inch (19.1 mm) for 2 and 2.5-ton units to 7/8 inch (22.2 mm) for 3, 3.5, and 4-ton units, and 1-1/8 inch (28.6 mm) for 4 and 5-ton units.
Coil: Condenser coils feature 5/16 inch (8 mm) tube diameter with 8 tubes and 1 or 2 rows, and a fin density of 22 fins per inch (866 fins per meter). Net face area varies by model.
Shipping Weight: Shipping weights range from 155 lbs (70 kg) for the 2-ton unit to 254 lbs (115 kg) for the 5-ton unit.

Usage Features:

Control Box: The control box houses the compressor contactor (K1) and dual capacitor (C12). It does not include a 24V transformer; 24 VAC controls are powered by the indoor unit. Field thermostat wiring connects to color-coded pigtail connections.
Compressor Contactor (K1): A single-pole contactor energizes the compressor. It is activated by the indoor thermostat's Y1 terminal (24V) when cooling demand is present.
Dual Capacitor (C12): A single "dual" capacitor is used for both the fan motor and the compressor, located within the control box.
Timed Off Control (TOC) (Option): This optional feature provides a time delay (5 ± 2 minutes, up to 8 minutes) between cycles to prevent short cycling of the compressor. If the TOC fails, it must be replaced and not bypassed.
Scroll Compressor: The scroll compressor design is simple, efficient, and tolerant to liquid return. It's important to note that scroll compressors should never be used for evacuating or pumping the system into a vacuum, as this can cause internal damage and void warranty claims.
Service Valves: Ball-type full service valves are used for both liquid and suction lines. They are not rebuildable. Each valve is equipped with a service port and a factory-installed Schrader valve, protected by a service port cap.
Charging Procedures: The manual outlines detailed charging procedures based on the refrigerant metering device (TXV or fixed orifice) and outdoor ambient temperature.
- Approach Method (TXV Systems, Outdoor Temp. > 65°F/18°C): Involves subtracting the outdoor ambient temperature from the liquid line temperature to determine the "Approach Temperature," which should match values provided in a table.
- Subcooling Method (TXV & Fixed Orifice Systems, Outdoor Temp. > 65°F/18°C): Requires recording liquid line temperature and pressure, determining saturation temperature from a chart, and calculating subcooling. This value is then compared to a table for adjustment.
- Weighing in the Charge (Fixed Orifice or TXV Systems, Outdoor Temp. < 65°F/18°C): If the system is void of refrigerant or the outdoor ambient is cool, the charge should be weighed in according to the unit nameplate.
Pumping Down System: The system can be pumped down for leak checking or repairs. It's critical not to operate the compressor at 0 psig or lower during this process to avoid damage.
Leak Testing: Before evacuating, the line set and indoor coil should be pressurized with dry nitrogen to 150 psig (1034 kPa) and checked for leaks using an electronic leak or Halide detector. A pressure reducing regulator must always be used with dry nitrogen.
Evacuating the System: The system must be evacuated to 29 inches (737mm) vacuum, and then to .5mm of mercury absolute pressure or 500 microns within a 20-minute period after stopping the vacuum pump. A temperature vacuum gauge, mercury vacuum (U-tube), or thermocouple gauge is recommended for accuracy.
Operating Sequence (Cooling):
1. Cooling demand initiates at Y1 on the thermostat.
2. 24VAC from the indoor unit (Y1) energizes the timed off control (if used), which then energizes the compressor contactor K1 after the 5-minute delay.
3. K1-1 N.O. closes, energizing the compressor (B1) and outdoor fan motor (B4).
4. Compressor (B1) and outdoor fan motor (B4) begin immediate operation.
Operating Sequence (End of Cooling Demand):
1. Cooling demand is satisfied, and terminal Y1 is de-energized.
2. Compressor contactor K1 is de-energized.
3. K1-1 opens, and the compressor (B1) and outdoor fan motor (B4) are de-energized and stop immediately.

Maintenance Features:

General Maintenance (Beginning of each cooling season):
- Outdoor Unit: Clean and inspect the condenser coil (can be flushed with a water hose). Visually inspect all connecting lines, joints, and coils for oil leaks. Outdoor fan motors are permanently lubricated and do not require oiling.
- Indoor Coil: Clean the coil if necessary. Check connecting lines and coil for oil leaks. Check and clean the condensate line.
- Indoor Unit: Clean or change filters. Bearings are pre-lubricated. Check all wiring for loose connections, correct voltage at the unit, and amp-draw on the blower motor.
Condenser Fan Motor Access: To access the condenser fan motor, remove seven screws securing the fan assembly. The motor is then removed from the fan guard by removing four nuts from the top panel. Drip loops should be used in wiring during motor servicing.
Safety Precautions:
- Electrical Safety: Always disconnect all power before beginning electrical service procedures. 13ACC units use single-pole contactors, meaning one leg of the compressor, capacitor, and condenser fan are always connected to line voltage. Potential for electrical shock exists.
- Refrigerant Handling: Refrigerant can be harmful if inhaled. It must be used and recovered responsibly.
- Electrostatic Discharge (ESD): Take precautions during unit installation and service to protect electronic controls. Neutralize electrostatic charge by touching an unpainted unit surface before any service procedure.
- Service Valve Backseating: Do not attempt to backseat the service valve, as this can cause the snap ring to explode from the valve body due to refrigerant pressure, leading to injury and unit damage.
- Dry Nitrogen Use: When using dry nitrogen, a pressure reducing regulator must be used to prevent excessive pressure in the gauge manifold, connecting hoses, and within the system. The regulator setting must not exceed 150 psig (1034 kPa).