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Installation, Start-Up
and Service Instructions
CONTENTS
Page
SAFETY CONSIDERATIONS ...................2
INSTALLATION .............................2-34
General ......................................2
Unit Clearances ..............................2
Roof Curb ...................................2
Roof Openings ...............................2
Rigging Unit .................................5
Unit Positioning ..............................5
Removing Shipping Shields ..................5
Field-Fabricated Ductwork ....................5
Condensate Drains ...........................9
Gas Piping (48MA) ...........................9
Optional Glycol Connections (50ME) .........10
Field Power Supply Wiring ..................10
• UNIT COMMON FEED MINIMUM CIRCUIT AMPS
Field Control Wiring .........................14
• ZONE THERMOSTATS
• ZONE MODULE CONNECTIONS
• ACCESSORY REMOTE CONTROL PANEL
Reheat Humidity Control ....................34
Optional Economizer ........................34
Optional Exhaust Damper ...................34
START-UP ................................34-39
Evaporator Fan .............................34
Compressor Rail Shipping Bolts .............34
Refrigerant Valves ..........................34
Zone Module Gas Valves (48MA) .............34
Gas Heat Lighting Procedure (48MA) .........35
• TO SHUT OFF GAS HEAT
Intermittant Pilots (48MA) ...................35
• ADJUSTMENT
• PRESSURE ADJUSTMENT (NATURAL GAS)
Main Burner Adjustment (48MA) .............36
• ORIFICE ALIGNMENT
• PRIMARY AIR ADJUSTMENT
Outdoor-Air Thermostat Adjustment
(50ME With Electric Heat) ..................36
• UNITS WITH 2-ELEMENT HEATERS
• UNITS WITH 3-ELEMENT HEATERS
Optional Glycol Heating Coils ................38
Zone Airflow Adjustment ....................38
Sequence of Operation .....................38
• COOLING
• HEATING (48MA)
• HEATING (50ME WITH ELECTRIC HEAT)
• HEATING (50ME WITH GLYCOL HEATING COILS)
• OUTDOOR-AIR DAMPER
SERVICE ..................................39-43
Cabinet Panels and Grilles ..................39
• SIDE PANELS
• TOP PANELS
• HEATER ACCESS PANELS
Cleaning ....................................39
• EVAPORATOR COILS (ZONE COOLING COILS)
AND GLYCOL HEATING COILS
• CONDENSER AND OUTDOOR-AIR COOLING
COILS
• CONDENSATE DRAINS
• INDOOR-AIR FILTERS
• OUTDOOR-AIR INLET SCREENS
• GAS HEATING SECTION
• COMBUSTION AIR FAN
Airflow Switches ............................39
• INDOOR AIRFLOW SWITCH (AFS1)
• COMBUSTION AIRFLOW SWITCH (AFS2)
Service Switch ..............................39
Time Guardா Control Circuit .................39
Capacity Control Pressure Switches (CCP)
(2-Compressor Units Only) ................39
Compressor Oil .............................39
• TO ADD OR REMOVE OIL
Compressor Capacity Control Unloader(s) ....40
• CONTROL SET POINT
• PRESSURE DIFFERENTIAL
Crankcase Heater(s) .........................40
Refrigerant Charge ..........................40
• NO CHARGE
• LOW CHARGE
Head Pressure Control ......................40
• MOTORMASTER HEAD PRESSURE CONTROL
DEVICE
• FAN CYCLING PRESSURESTAT
Condenser Fans ............................41
• ADJUSTMENT
• FAN MOTOR REMOVAL
• LUBRICATION
Evaporator Fans and Motor ..................41
• MOTOR REMOVAL
• FAN SHAFT BEARING REMOVAL
• FAN SPEED ADJUSTMENT
• PULLEY REMOVAL
• PULLEY ALIGNMENT
• BELT TENSION ADJUSTMENT
• LUBRICATION
Forced-Draft Blower (48MA) .................42
• LUBRICATION
• AIR SHUTTER ADJUSTMENT
Zone Module Transformers ..................42
Optional Economizer ........................42
• THERMOSTAT SETTINGS
• DAMPER POSITION
• OPERATION
Optional Exhaust Damper ...................42
Replacement Parts ..........................42
START-UP CHECKLIST .....................CL-1
48MA/50ME016-040
Combination Multizone Heating/Cooling Units
Gas, Electric, or Glycol Heat
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 1
Tab 1c 1d
PC 111 Catalog No. 564-840 Printed in U.S.A. Form 48MA/50ME-3SI Pg 1 4-96 Replaces: 48MA/50ME-1SI