Carrier 48AK - User Manual

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 534-739 Printed in U.S.A. Form 48A,E-1SI Pg 1 107 11-01 Replaces: 48E-6SI
Book 1
Ta b 1 a
Installation, Start-Up and
Service Instructions
CONTENTS
Page
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . 1
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-58
Step 1 — Provide Unit Support . . . . . . . . . . . . . . . . . . . 1
• ROOF CURB
• ALTERNATE UNIT SUPPORT
Step 2 — Rig and Place Unit . . . . . . . . . . . . . . . . . . . . . 2
• POSITIONING
• ROOF MOUNT
Step 3 — Field Fabricate Ductwork. . . . . . . . . . . . . . . 2
Step 4 — Make Unit Duct Connections . . . . . . . . . . . 2
Step 5 — Install Flue Hood . . . . . . . . . . . . . . . . . . . . . . 28
Step 6 — Trap Condensate Drain . . . . . . . . . . . . . . . . 28
Step 7 — Install Gas Piping . . . . . . . . . . . . . . . . . . . . . 28
Step 8 — Controls Options . . . . . . . . . . . . . . . . . . . . . . 29
• STAGED GAS UNIT APPLICATIONS
• THERMISTORS
• CONSTANT VOLUME APPLICATIONS
• VARIABLE AIR VOLUME (VAV) APPLICATIONS
Step 9 — Make Electrical Connections . . . . . . . . . . 33
•POWER WIRING
• FIELD POWER SUPPLY
• FIELD CONTROL WIRING
Step 10 — Make Outdoor-Air Inlet
Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
• ECONOMIZER
• ECONOMIZER SETTINGS
Step 11 — Position Power Exhaust/Barometric
Relief Damper Hood. . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Step 12 — Install All Accessories . . . . . . . . . . . . . . . 54
Step 13 — Field Modifications. . . . . . . . . . . . . . . . . . . 57
START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58-89
SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89-102
TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . 103-115
START-UP CHECKLIST . . . . . . . . . . . . . . . . . . . CL-1,CL-2
SAFETY CONSIDERATIONS
Installation and servicing of air-conditioning equipment can
be hazardous due to system pressure and electrical compo-
nents. Only trained and qualified service personnel should in-
stall, repair, or service air-conditioning equipment.
Untrained personnel can perform the basic maintenance
functions of cleaning coils and filters and replacing filters. All
other operations should be performed by trained service per-
sonnel. When working on air-conditioning equipment, observe
precautions in the literature, tags and labels attached to the unit,
and other safety precautions that may apply.
Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloth for unbrazing operations. Have
fire extinguishers available for all brazing operations.
INSTALLATION
Step 1 — Provide Unit Support
Before performing service or maintenance operations on
unit, turn off main power switch to unit. Electrical shock
could cause personal injury.
1. Improper installation, adjustment, alteration, service,
or maintenance can cause property damage, personal
injury, or loss of life. Refer to the User’s Information
Manual provided with this unit for more details.
2. Do not store or use gasoline or other flammable va-
pors and liquids in the vicinity of this or any other
appliance.
What to do if you smell gas:
1. DO NOT try to light any appliance.
2. DO NOT touch any electrical switch, or use any
phone in your building.
3. IMMEDIATELY call your gas supplier from a neigh-
bor’s phone. Follow the gas supplier’s instructions.
4. If you cannot reach your gas supplier, call the fire
department.
Disconnect gas piping from unit when pressure testing at
pressure greater than 0.5 psig. Pressures greater than
0.5 psig will cause gas valve damage resulting in hazardous
condition. If gas valve is subjected to pressure greater than
0.5 psig, it must be replaced before use. When pressure
testing field-supplied gas piping at pressures of 0.5 psig or
less, a unit connected to such piping must be isolated by
closing the manual gas valve(s).
1. All panels must be in place when rigging.
2. Unit is not designed for handling by fork truck.
48AJ,AK,AW,AY020-060
with Reciprocating Compressor
48EJ,EK,EW,EY024-068
Single Package Rooftop Units
Electric Cooling/Gas Heating

Summary

SAFETY CONSIDERATIONS

INSTALLATION

Step 1 - Provide Unit Support

Details on supporting the unit, including roof curb and alternate methods.

Step 2 - Rig and Place Unit

Instructions for rigging, placing, positioning, and roof mounting the unit.

Step 7 - Install Gas Piping

Step 8 - Controls Options

VARIABLE AIR VOLUME (VAV) APPLICATIONS

Details on VAV unit operation, including sensors and timeclocks.

Step 9 - Make Electrical Connections

POWER WIRING

Factory wiring for unit voltage and NEC compliance, including wire sizing.

FIELD POWER SUPPLY

Field wiring connections for unit power supply, including conduit and knockout details.

FIELD CONTROL WIRING

Thermostat Wiring (CV Only)

Sensor Wiring (CV or VAV)

Step 10 - Make Outdoor-Air Inlet Adjustments

ECONOMIZER

General information on the economizer system and its components.

Minimum Damper Position (MDP) Setting

ECONOMIZER SETTINGS

Step 11 - Position Power Exhaust;Barometric Relief Damper Hood

Step 12 - Install All Accessories

MOTORMASTER III CONTROL INSTALLATION

Installation steps for the Motormaster III control system.

Install Motormaster III Controls

Electrical Connections

Wiring procedures for connecting the Motormaster III control to the unit.

Step 13 - Field Modifications

DUCTWORK

Field modifications related to ductwork, including side return conversions.

Bottom Return Units (48 AJ,AK,EJ,EK) Field-Modified for Side Return

START-UP

Unit Preparation

Verifying correct installation and removal of packing materials.

Variable Frequency Drive (VFD)

Power Exhaust

Direct Digital Controls DIP Switch Configuration

Sequence of Operation

COOLING, CONSTANT VOLUME (CV) UNITS

Describes the cooling operation for CV units, including compressor staging.

GAS HEATING, VARIABLE AIR VOLUME (VAV) UNITS

STAGED GAS UNIT HEATING

SUPPLY AIR TEMPERATURE RESET

POWER EXHAUST OPERATION

SMOKE CONTROL MODES

INDOOR AIR QUALITY (IAQ) CONTROL

CAPACITY CONTROL, COOLING

SERVICE

MAIN BURNERS

Lubrication

COMPRESSORS

Evaporator Fan Service and Replacement

Evaporator-Fan Motor Replacement

Condenser-Fan Adjustment

Refrigerant Charge

LOW CHARGE COOLING

Thermostatic Expansion Valve (TXV)

Gas Valve Adjustment

Main Burners

Protective Devices

COMPRESSOR PROTECTION

Details on overcurrent and overtemperature protection for compressors.

EVAPORATOR FAN MOTOR PROTECTION

Protection mechanisms for the evaporator fan motor against overcurrent.

CONDENSER-FAN MOTOR PROTECTION

HIGH- AND LOW-PRESSURE SWITCHES

Function and impact of high and low-pressure switches on refrigerant circuits.

FREEZE PROTECTION THERMOSTAT (FPT)

Power Circuit

Control Circuit, 24-V

Control Circuit, 115-V

Compressor Lockout Logic

TROUBLESHOOTING

START-UP CHECKLIST

PRE-START-UP:

Initial checks before powering up the unit.

START-UP:

Checks to perform during the start-up process.

ELECTRICAL

Electrical checks including voltage and current measurements.

TEMPERATURES

PRESSURES

Carrier 48AK Specifications

General

Brand	Carrier
Model	48AK
Category	Air Conditioner
Language	English