Page 1: Table Of Contents
Replacement Parts ......42 START-UP CHECKLIST ..... CL-1 Printed in U.S.A. Form 48MA/50ME-3SI 48MA/50ME016-040 Pg 1 4-96 Replaces: 48MA/50ME-1SI...
Page 2: Safety Considerations
SAFETY CONSIDERATIONS Installation and servicing of air-conditioning equipment can be hazardous due to system pressure and electrical com- ponents. Only trained and qualiﬁed service personnel should install, repair, or service air-conditioning equipment. Untrained personnel can perform basic maintenance func- tions of cleaning coils and ﬁlters and replacing ﬁlters. All other operations should be performed by trained service per- sonnel.
Page 3 CONDENSER SECTION AIRFLOW CONN — Connection NOTES: 1. Space required for service and airﬂow all around and above unit is 36 inches. 2. For additional information see Fig. 4. 3. Center of gravity is within 6 in. radius of geo- metric center of unit.
Page 4 CONDENSER SECTION AIRFLOW CONN — Connection NOTES: 1. Space required for service and airﬂow all around and above unit is 36 inches. 2. For additional information see Fig. 5. 3. Center of gravity is within 6 in. radius of geo- metric center of unit.
Page 5: Rigging Unit
AIRFLOW *Factory supplied (with accessory roof curb). †Field supplied (when using accessory roof curb). NOTE: Dimensions are in inches. Rigging Unit — Inspect unit for shipping damage, and ﬁle any damage claim immediately with transportation company. Lift unit with cables and spreader bars, using lifting brack- ets provided (Fig.
Page 6 UNIT 48MA/50ME Zone Modules (Quantity) Nominal Cooling Capacity (tons) OPERATING WEIGHT (lb) Base Unit 48MA Base Unit 50ME (with electric heat) Roof Curb REFRIGERANT CHARGE — R-22 (lb) COMPRESSOR No. 1 Type Cylinders...Unloaders No. 2 Type Cylinders (have no unloaders) System Oil Charge (pints) Unloader Settings (psig) Loads...
Page 7 UNIT 48MA 016-030 18-2 ⁄ 7- 3 11-9 034,040 21-9 ⁄ 7-11 ⁄ 14-1 ⁄ Fig. 4 — Roof Curb Physical Data and Dimensions; 48MA Units EVAPORATOR (ZONE MODULE) AIRFLOW CONN — Connection *Not used on 48MA016,024 (8 zone module units). NOTES: 1.
Page 8 END DETAIL (034,044 12-ZONE MODULES) UNIT 50ME 016-030 18-2 ⁄ 7- 3 034,040 21-9 ⁄ 7-11 Fig. 5 — Roof Curb Physical Data and Dimensions; 50ME Units CONN — Connection *Not used on 50ME016,024 (8 zone module units). NOTES: 1. For additional information, see Table 1 and Fig. 2. 2.
Page 9: Condensate Drains
Condensate Drains — Pipe nipples covered with foam rubber insulation are shipped in unit return air ﬁlter section (6 nipples in units 48MA, 4 nipples in units 50ME). Install a nipple in each drain connection on both sides of unit. See Fig.
Page 10: Optional Glycol Connections (50Me)
*Shutoff valve not used except where required by code. Properly cap any gas connection not being used. Fig. 8 — Suggested Gas Piping (48MA) Unit has factory-installed gas shutoff valves. Install gas shutoff valve external to unit if required by code (Fig. 8). After piping is complete, pressurize gas line and check for leaks with soap and water solution.
Page 11 Use the following formula to determine the percent volt- age imbalance. % Voltage Imbalance: max voltage deviation from average voltage = 100 × average voltage EXAMPLE: Supply voltage is 460-3-60. AB = 452 v BC = 464 v AC = 455 v 452 + 464 + 455 Average Voltage = 1371...
Page 12 VOLTAGE UNIT VOLTAGE RANGE 50ME (3 Ph, 60 Hz) 208/230 208/230 208/230 208/230 208/230 208/230 LEGEND COMP — Compressor — Full Load Amps — Indoor (Evaporator) Fan Motor — Locked Rotor Amps — Minimum Circuit Amps MOCP — Maximum Overcurrent Protection —...
Page 13 Table 5 — Unit 50ME Electrical Application Data UNIT 50ME NOMINAL VOLTAGE Size 208/230 208/230 208/230 208/230 208/230 208/230 208/230 208/230 LEGEND — Indoor (Evaporator) Fan Motor MCA — Minimum Circuit Amps (Unit Cooling Total) 43/ 53 150.0/165.6 57/ 70 109.8/109.8 200.0/220.9 87/106...
Page 14: Field Control Wiring
Field Control Wiring ZONE THERMOSTATS — Install a Carrier approved ac- cessory zone thermostat assembly in each zone according to installation instructions included in the accessory. Locate each thermostat assembly in the space where it will sense average zone temperature.
Page 15 Fig. 10 — Zone Control Board Component Location (cont)
Page 16 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 11 — 48MA; One-Stage Heat, One-Stage Cool — 2 Nested Modules, Joint Zone Control *One for each module.
Page 17 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 12 — 48MA; One-Stage Heat, Two-Stage Cool — 2 Nested Modules, Joint Zone Control *One for each module.
Page 18 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 13 — 48MA; One-Stage Heat, One-Stage Cool — One Independent Module, 2 Joint Modules Zone Control *One for each module.
Page 19 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 14 — 48MA; One-Stage Heat, One-Stage Cool; One-Stage Heat, Two-Stage Cool Combination *One for each module.
Page 20 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 15 — 48MA; One-Stage Heat, One-Stage Cool — 4 Module Joint Zone Control *One for each module.
Page 21 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 16 — 48MA; One-Stage Heat, One-Stage Cool — One Independent Module, 3 Joint Modules Zone Control *One for each module.
Page 22 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 17 — 48MA; One-Stage Heat, Two-Stage Cool — 4 Module Joint Zone Control *One for each module.
Page 23 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 18 — 48MA; One-Stage Heat, Two-Stage Cool — 3 Module Joint Zone Control *One for each module.
Page 24 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 19 — 48MA; One-Stage Heat, One-Stage Cool — 2 Independent Modules, 2 Joint Modules Zone Control *One for each module.
Page 25 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 20 — 50ME; Two-Stage Heat, One-Stage Cool — 2 Modules, Joint Zone Control *One for each module.
Page 26 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 21 — 50ME; Two-Stage Heat, Two-Stage Cool — 2 Modules, Joint Zone Control *One for each module.
Page 27 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 22 — 50ME; Two-Stage Heat, One-Stage Cool — One Independent Module, 2 Joint Modules Zone Control *One for each module.
Page 28 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 23 — 50ME; Two-Stage Heat, One-Stage Cool; Two-Stage Heat, Two-Stage Cool Combination *One for each module.
Page 29 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 24 — 50ME; Two-Stage Heat, One-Stage Cool — 4 Module Joint Control *One for each module.
Page 30 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 25 — 50ME; Two-Stage Heat, One-Stage Cool — One Independent Module, 3 Joint Modules Zone Control *One for each module.
Page 31 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 26 — 50ME; Two-Stage Heat, Two-Stage Cool — 4 Module Joint Zone Control *One for each module.
Page 32 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 27 — 50ME; Two-Stage Heat, Two-Stage Cool — 3 Module Joint Zone Control *One for each module.
Page 33 LEGEND — Contactor — Control Relay — Gas Valve — Heat Anticipator — Heating Relay — Thermostat, Cooling — Thermostat, Heating TRAN — Transformer Screw Terminal Quick-Connect Terminal Factory Control Wires Printed Circuit Field Wiring Fig. 28 — 50ME; Two-Stage Heat, One-Stage Cool — 2 Independent Modules, 2 Joint Modules Zone Control *One for each module.
Page 34: Accessory Remote Control Panel Reheat Humidity Control
ACCESSORY REMOTE CONTROL PANEL — This central- station control can be set to override zone thermostat mode settings to lock out heating or cooling for the entire unit. The DAY/NIGHT switch and damper position knob provide in- space, central control of damper position. Panel also houses the ﬁlter light to indicate reduced airﬂow and need for clean ﬁlters.
Page 35: Gas Heat Lighting Procedure (48Ma)
LEGEND HA — Heat Anticipator HU — Humidistat TC — Thermostat, Cooling TH — Thermostat, Heating Fig. 30 — Humidistat Connections LEGEND — Capacity Control Pressure Switch — Discharge Line Thermostat FCPS — Fan Cycling Pressure Switch — Fusible Plug HGBP —...
Page 36: Pressure Adjustment (Natural Gas)
LEGEND — Gas Valve (Zone Module) — Main Burner MGV — Main Manual Gas Valve — Pilot Burner Fig. 32 — Gas Piping Schematic (10-Zone 48MA Unit Shown — 8- and 12-Zone Units Similar) 3. Turn system switch to ON position. Set each zone ther- mostat at setting to call for heat.
Page 37 Fig. 33 — Spoiler Screw Location LEGEND COMPR — Compressor COND — Condensing *AFS1 deenergizes control circuit if loss of indoor air occurs. †Factory-supplied option. Fig. 34 — Major Component Identiﬁcation (Typical 10-Zone Unit Shown; 8-Zone Units Similar)
Page 38: Units With 2-Element Heaters
HTR — Heater *AFS1 deenergizes control circuit if loss of outdoor air occurs. †Factory-supplied option. Fig. 35 — Major Component Identiﬁcation (Typical 12-Zone Unit Shown). When OAT is open, ﬁnal stage heating element in all zone modules is inactive. When OAT is closed, ﬁnal stage heating element in a zone module may be energized whenever second- stage thermostat for that zone module calls for heat as follows:...
Page 39: Heating (50Me With Electric Heat)
HEATING (48MA) — On call for heating from a zone, the forced draft blower will start and the pilot will light. The zone burner will ignite after the pilot has been proven. (Ap- proximately 60 seconds.) NOTE: A time-delay relay will shut unit down in 180 sec- onds if the unit main gas valve is not open.
Page 40: To Add Or Remove Oil
TO ADD OR REMOVE OIL 1. Close liquid line and hot gas bypass shutoff valves. See Fig. 31. 2. Pump down compressor and close suction and discharge service valves. Recover remaining refrigerant in compressor. 3. Add oil through oil ﬁller plug. 4.
Page 41: Condenser Fans
Fig. 37 — Motormaster Thermistor Locations on Condenser Coil Condenser Fans Shut off service switch to deenergize condenser-fan motors. ADJUSTMENT — Remove fan guard from top of unit. Re- move rubber hubcap from fan hub and loosen fan hub set- screws.
Page 42: Pulley Removal
The condenser fans pull indoor re- turn air through the open exhaust damper and discharge it to the outdoors. Replacement Parts — parts may be obtained from any Carrier distributor upon request. 48MA028-040 Fig. 39 — Forced-Draft Blower Shutter Position See Fig.
Page 43 LEGEND 1 — Bearing Liner 2 — Speed Nut ( ⁄ in.) 3 — Washer 4 — Rivet 5 — Speed Nut ( ⁄ in.) 6 — Speed Nut ( ⁄ in.) 7 — Damper Lever 8 — Linkage Bar 9 —...
Page 46 For a free Service Training Material Catalog (STM), call 1-800-962-9212. Ordering instructions are included. Copyright 1996 Carrier Corporation Manufacturer reserves the right to discontinue, or change at any time, speciﬁcations or designs without notice and without incurring obligations. Book 1 1 PC 111 Catalog No.
Page 48: Start-Up Checklist
VERIFY REFRIGERANT CHARGE GENERAL ECONOMIZER MINIMUM VENT AND CHANGEOVER SETTINGS TO JOB REQUIREMENTS Copyright 1996 Carrier Corporation Manufacturer reserves the right to discontinue, or change at any time, speciﬁcations or designs without notice and without incurring obligations. Book 1 1 PC 111 Catalog No.

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