Carrier 38AKS028-044 Installation, Start-up And Service Instructions Manual

Contents

START-UPInitial CheckDo not attempt to start the condensing unit, even mo-mentarily, until the following steps have been com-pleted. Compressor damage may result.1. Check all auxiliary components, such as air-handling equip-ment, and other equipment. Consult the manufacturer’sinstructions regarding any other equipment connectedto the condensing unit. If used, airflow switch must beproperly installed. See Fig. 8.2. Backseat (open) compressor suction and discharge valves.Close valves one turn to allow pressure to reach test gages.3. Open liquid line service valve.4. Set thermostat.5. Check tightness of all electrical connections.6. Compressor oil level should be visible in sight glass.See Service, Oil Charge section on page 19.7. Be sure unit is properly leak tested, dehydrated, and charged.See below.8. Electrical power source must agree with nameplaterating.9. Crankcase heater must be firmly locked into compres-sor crankcase. Be sure crankcase is warm (heater shouldbe on for 24 hours before starting compressor).10. Be sure compressor floats freely on the mounting springs.See Compressor Mounting section on page 2 and Fig. 3for loosening compressor bolts.Leak Test and Dehydration — Leak test the entirerefrigerant system by the pressure method described in theCarrier Training Booklet; GTAC II, Module 4 - SystemDehydration.Preliminary Charge — Refer to Carrier Training Book-let; GTAC II, Module 5 for charging methods and proce-dures. Charge system with approximately 25 lbs (11.3 kg) ofR-22 by the liquid charging method (charging through liq-uid service valve), on the high side, and charging by weight.Charge per Fig. 10-12.Start Unit — Close field disconnect. Set thermostat aboveambient temperature so that there is no demand for cooling.Now, only the crankcase heater is energized. After the heaterhas been on for 24 hours, the unit can be started. If no timehas elapsed since the preliminary charge step has been com-pleted, it is unnecessary to wait the 24-hour period.Close the compressor circuit breaker, then reset the in-door thermostat below ambient temperature, so that a callfor cooling is ensured.NOTE: Do not use the compressor circuit breaker to startand stop compressor, except in an emergency.The start-up of the compressor can occur between 3 secondsand approximately 5 minutes from the time the control cir-cuit is energized due to the anti-short cycle feature of thecontrol module (CM).Charge System — Actual start-up should be done onlyunder supervision of a qualified refrigeration mechanic. Re-fer to charging charts.See Fig. 10-12 for the particular unit being charged. Mea-sure pressure at the liquid line service valve, being sure aSchrader depressor is used if required. Also, measure liquidline temperature as close to the liquid service valve as pos-sible. Add or reduce charge until the pressure and tempera-ture conditions of the charging charge curve are met. If liq-uid pressure and temperature point fall above curve, add charge.If liquid pressure and temperature point fall below curve,reduce the charge until the conditions match the curve.Never charge liquid into the low-pressure side of sys-tem. Do not overcharge. During charging or removal ofrefrigerant, be sure indoor fan system is operating.Operation — Refer to control circuit diagram on the unit,or in the unit wiring book.Control Module (CM) — The unit control module islocated in the control section of the control box. SeeFig. 9A or 9B. It performs several functions. The CM has abuilt-in compressor anti-short-cycle timer which will not al-low the compressor to restart until 5 minutes (190 seconds/–75 seconds) have elapsed since the previous shutdown.The compressor oil pressure is monitored through the CM.The unit is allowed to remain operational as long as the oilpressure safety switch (OPS) has not been open for morethan 2 minutes after the compressor has started. If after start-up, the OPS is open for more than 2 minutes, the CM shutsdown the compressor and places the unit in a lockout con-dition. The CM activates the fault indication circuit, and thefield-supplied unit service lamp is illuminated (if so equipped).The unit cannot be restarted until power is interrupted at theunit, resetting the CM. The 5-minute recycle time relay isinitiated.The CM also monitors the high-pressure switch (HPS) andcompressor thermal protection. If at any time the HPS opens,the CM shuts down the compressor and places the unit in alockout condition. The CM activates the fault indication cir-cuit, and the field-supplied unit service lamp is illuminated(if so equipped). The unit cannot be restarted until the HPSis reset and until power is interrupted at the unit, resettingthe CM. The 5-minute recycle time relay is initiated.If the unit shuts down on an automatic reset switch, suchas the low-pressure switch (LPS), the compressor will be al-lowed to restart when the switch recloses and the CM anti-short-cycle time has elapsed.13