Assessments - 2, GPA: 4
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Control Circuit .................39 Capacity Control Pressure Switches (CCP) (2-Compressor Units Only) ................39 Compressor Oil .............................39 • TOADDORREMOVEOIL Compressor Capacity Control Unloader(s) ....40 • CONTROLSETPOINT • PRESSUREDIFFERENTIAL Crankcase Heater(s) .........................40 Refrigerant Charge ..........................40 • NOCHARGE • LOWCHARGE Head Pressure Control ......................40 • MOTORMASTER. HEADPRESSURECONTROL DEVICE • FANCYCLINGPRESSURESTAT Condenser Fans ............................41 • ADJUSTMENT • FANMOTORREMOVAL • LUBRICATION Evaporator Fans and Motor ..................41 • MOTORREMOVAL • FANSHAFTBEARINGREMOVAL • FANSPEEDADJUSTMENT • PULLEYREMOVAL • PULLEYALIGNMENT • BELTTENSIONADJUSTMENT • LUBRICATION Forced-Draft Blower (48MA) .................42 • LUBRICATION • AIRSHUTTERADJUSTMENT Zone Module Transformers ..................42 Optional Economizer ........................42 • THERMOSTATSETTINGS • DAMPERPOSITION • OPERATION Optional Exhaust Damper ...................42 Replacement Parts ..........................42 START-UP CHECKLIST .....................CL-1 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. 564-840 Printed in U.S.A. Form 48MA/50ME-3SI Pg 1 4-96 Replaces: 48MA/50ME-1SI Tab 1c 1d SAFETY CONSIDERATIONS INSTALLATION Installation and servicing of air-conditioning equipment can be hazardous due to system pressure and electrical components. Only trained and qualified service personnel should install, repair, or service air-conditioning equipment. Untrained personnel can perform basic maintenance functions of cleaning coils and filters and replacing filters. All other operations should be performed by trained service personnel. 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, including ANSI (American National Standards Institute) Z223.1. Wear safety glasses and work gloves. Use quenching cloth for unbrazing operations. Have fire extinguisher available for all brazing operations. Before performing service or maintenance operations on unit, turn off main power switch to unit. Electrical shock could cause personal injury. Do not try to light any appliance. Do not touch any electrical switch; do not use any phone in your building. Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. If you cannot reach your gas supplier, call the fire department. Do not store or use gasoline or other flammable vapors and liquids in the vicinity of the 48MA unit or any other gas-fired appliance. Improper installation, adjustment, alteration, service, or maintenance can cause injury or property damage. Refer to this manual. For assistance or additional information, consult a qualified installer, service agency, or the gas supplier. Disconnect gas piping from 48MA unit when leak testing at pressures greater than 0.5 psig. Pressures greater than 0.5 psig will cause gas valve damage resulting in a hazardous condition. If gas valve is subjected to pressure greater than 0.5 psig, it must be replaced. When pressure testing field-supplied gas piping at pressures of 0.5 psig or less, the unit connected to such piping must be isolated by manually closing the gas valve. General — Install unit on rooftop, outdoor site only. Install unit, electrical wiring, gas supply line (48MA) and condensate drain lines in accordance with all applicable codes. Unit Clearances — See Fig. 1 and 2 for service and airflow clearances. For 48MA gas-fired units, provide not less than 36-in. clearance to combustibles from top and all sides. Keep burner end free from any obstruction. Locate exit terminals of mechanical draft system (48MA flue outlet) as follows: • Not less than 12 in. from any opening through which combustion products could enter the building. • Not less than 2 ft from any adjacent building. • Not less than 7 ft above grade when unit is adjacent to public walkways. Roof Curb — Assemble and install per instructions shipped with this accessory. Information required to field fabricate a roof curb and other curb data are shown in Fig. 3-5. Install field-supplied insulation, cant strips, roofing and counter flashing as required. Seal all curb joints with mastic or other suitable roof cement to keep out moisture. Be sure that run-off pan at compressor end of curb is completely flashed and sealed. Seal strip (Fig. 3) is shipped with accessory roof curb. Install as described in the roof curb installation instructions. The seal strip compresses under unit weight so that an airtight seal and vibration isolation are provided between unit base and curb. Roof Openings — Except for the compressor and condenser section, roof area under the unit need not be filled in as the cur...