Lennox 10ACC Series - User Manual

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Summary

UNIT INFORMATION

10 ACC Series Overview

Overview of 10ACC condensing units, sizes, SEER rating, and compressor types.

Essential Safety Warnings

Critical warnings on refrigerant hazards and electrical shock risks before servicing.

GENERAL INFORMATION AND COMPONENTS

Unit Capacities and System Matching

Details on 10ACC unit capacities, system matching, and electrical safety warnings.

10 ACC Unit Component Identification

Illustration and identification of key unit components and control box configurations.

CONTROL BOX COMPONENTS

Compressor Contactor K1

Explanation of the compressor contactor's function and wiring in 10ACC units.

Dual Capacitor C12 Function

Description of the dual capacitor used for fan motor and compressor.

Optional Start Capacitor C7

Details on the optional start capacitor and its role in compressor startup.

Optional Potential Relay K31

Information on the optional potential relay and its function with the start capacitor.

SCROLL COMPRESSOR DETAILS

Scroll Compressor Design and Operation

Explanation of the scroll compressor design, operation, and handling precautions.

CONDENSER FAN MOTOR INFORMATION

Fan Motor Operation and Access

Details on the condenser fan motor's requirements, control, and steps for accessing it.

REFRIGERANT SYSTEM AND SERVICE VALVES

Plumbing and Line Set Specifications

Information on field refrigerant piping, line set types, and service port locations.

Service Valve Operation and Schrader Port Access

Instructions for operating liquid/suction line service valves and accessing Schrader ports.

SYSTEM CHARGING AND LEAK TESTING

Pumping Down the System Procedure

Procedure for pumping down the system, including cautions about deep vacuum.

System Leak Testing Steps

Steps for performing leak testing on the system using nitrogen before evacuation.

SYSTEM EVACUATION AND REFRIGERANT CHARGING

System Evacuation Procedure

Detailed steps for evacuating the system, including vacuum level and leak checks.

Refrigerant Charging Guidance

Guidance on charging the system based on line set length and ambient temperature.

REFRIGERANT CHARGING METHODS

Weighing in Charge for Cooler Temps

Method for weighing in refrigerant charge for fixed orifice or TXV systems in cooler temperatures.

Subcooling Method for Fixed Orifice Systems

Procedure for charging fixed orifice systems above 65°F using the subcooling method.

Approach Method for TXV Systems

Procedure for charging TXV systems at or above 60°F using the approach method.

MAINTENANCE AND CHECKS

Outdoor Unit Maintenance Tasks

Checks for condenser coil, connecting lines, wiring, and electrical parameters.

Evaporator Coil and Indoor Unit Checks

Maintenance for evaporator coil, condensate pan, filters, and blower motor.

WIRING DIAGRAM AND OPERATION SEQUENCE

10 ACC Cooling Operation Sequence

Describes the sequence of operation for the 10ACC unit during cooling mode.

The Lennox 10ACC is a residential split-system condensing unit designed for cooling applications. It is available in various sizes, ranging from 1-1/2 to 5 tons, and is engineered to achieve a minimum SEER rating of 10.0. The unit is compatible with either an expansion valve or an RFCIV system in the indoor unit.

Function Description:

The 10ACC unit's primary function is to provide cooling for residential spaces. It operates as part of a split-system, meaning it works in conjunction with an indoor evaporator coil and blower. The condensing unit, located outdoors, compresses and condenses refrigerant, which then circulates to the indoor coil to absorb heat from the indoor air, thus providing cooling.

Important Technical Specifications:

Capacities: Available in 1-1/2, 2, 2-1/2, 3, 3-1/2, 4, and 5 ton capacities.
Compressor Types:
- 10ACC 1-1/2 to 3 ton units are equipped with hermetically sealed reciprocating compressors. These compressors are mounted on resilient rubber to minimize vibration and noise, and include a built-in protection device against excessive current and temperatures.
- 10ACC 3-1/2 to 5 ton units feature scroll compressors, which are known for their efficiency and simple compression concept. Scroll compressors are tolerant to liquid return, as the orbiting scroll can separate from the stationary scroll to discharge liquid.
Refrigerant: Uses HCFC-22 refrigerant. The factory charge is sufficient for a 20 ft. (6.1 m) length of refrigerant lines. Specific charge amounts vary by model and are listed on the unit nameplate.
Electrical Data:
- Line voltage: 208/230V-1ph, 60Hz.
- Minimum circuit ampacity and maximum fuse sizes vary by model (e.g., 10ACC-018: 11.6 amps min. circuit, 20 amps max fuse; 10ACC-060: 35.5 amps min. circuit, 60 amps max fuse).
- Compressor rated load amps and locked rotor amps vary significantly by model.
- Condenser fan motor full load amps and locked rotor amps are also specified for each model.
Condenser Coil: Net face area, tube diameter (5/16 in. / 7.9 mm), number of rows (1), and fins per inch (22 / 866) are consistent across most models, though face area varies.
Condenser Fan: Diameter (16 in. / 406 mm to 22 in. / 559 mm), number of blades (3 or 4), motor horsepower (1/10 to 1/3 hp), CFM (L/s), RPM, and Watts vary by model.
Service Valves: Liquid line and suction line service valves are provided with sweat connections. Ball-type service valves are used on 5-ton units. Schrader valves are factory installed in service ports for leak testing, evacuation, and charging.
Control Box Components: Includes a compressor contactor (K1) and a dual capacitor (C12) for both the fan motor and compressor. Optional start capacitor (C7) and potential relay (K31) are used in reciprocating compressor units for enhanced starting.

Usage Features:

System Matching: Proper matching of indoor blower and coil with the condensing unit is crucial for warranty coverage and optimal operation. Refer to the Engineering Handbook for approved system matchups.
Charging Procedures:
- Weighing in the Charge: Recommended for systems void of refrigerant or when outdoor ambient temperature is below 60°F (16°C).
- Subcooling Method: Used for fixed orifice systems when outdoor ambient temperature is 65°F (18°C) or above. Requires measuring liquid line temperature and pressure.
- Approach Method: Used for TXV (Thermostatic Expansion Valve) systems when outdoor ambient temperature is 60°F (16°C) or above. Requires measuring liquid line temperature and outdoor ambient temperature.
Deep Vacuum Operation: Scroll compressors are capable of drawing a deeper vacuum than reciprocating compressors. However, deep vacuum operation (compressor operating at 0 psig or lower) should be avoided as it can cause internal fusite arcing and compressor failure. The compressor should never be used for evacuating or "pumping-down" the system.
Service Valve Operation: Instructions are provided for opening and closing liquid and suction line service valves, as well as accessing schrader ports for gauge manifold connection.
Electrical Controls: The unit's 24 VAC controls are powered by the indoor unit, as 10ACC units are not equipped with a 24V transformer.
Wiring: Detailed wiring diagrams and sequence of operation are provided for cooling cycles, including initiation and termination of cooling demand.

Maintenance Features:

Regular Checks: At the beginning of each cooling season, the system should be checked by a qualified installer or service agency.
Condenser Coil Cleaning: The condenser coil should be cleaned and inspected. It can be flushed with a water hose after ensuring power is off.
Leak Inspection: Visually inspect connecting lines and coils for evidence of oil leaks.
Electrical System Checks:
- Check wiring for loose connections.
- Verify correct voltage at the unit (when operating).
- Measure compressor and condenser fan motor amp-draw.
Refrigerant Charge Verification: If insufficient cooling is reported, the refrigerant charge should be checked using gauges and the appropriate charging method.
Evaporator Coil Maintenance: Clean the evaporator coil if necessary, check connecting lines and coils for oil leaks, and clean the condensate pan line.
Indoor Unit Maintenance: Clean or change filters, adjust blower speed for cooling (refer to service manual for pressure drop tables), check belt wear and tension for belt-drive blowers, and check wiring and voltage.

Safety Warnings:

Electrical Shock Hazard: Always disconnect all electrical power to the unit at the disconnect switch(es) before performing any service or maintenance. Units may have multiple power supplies. One leg of compressor, capacitor, and condenser fan are always connected to line voltage.
Refrigerant Handling: Refrigerant can be harmful if inhaled. It must be used and recovered responsibly.
Nitrogen Pressure: When using dry nitrogen for leak testing, a pressure-reducing regulator must be used to prevent excessive pressure in the gauge manifold, hoses, and system. Regulator setting must not exceed 150 psig (1034 kPa).
Service Valve Backseating: Do not attempt to backseat the service valves, as this can cause the snap ring to explode under refrigerant pressure, leading to personal injury and unit damage.
Qualified Personnel: Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life. Installation and service must be performed by a qualified installer or service agency.