Carrier 24ACB7 Performance Installation Instructions Manual

Also see for 24ACB7 Comfort: Product data Wiring diagram

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Carrier 24ACB7 Performance Installation Instructions Manual Manual pdf 6 page image

6Check ChargeThe 24ACB7 units may be charged in high-- or low--stagecompressor operation. Factory charge amount and desiredsubcooling are shown on unit rating plate. Charging method isshown on information plate inside unit. To properly check or adjustcharge, conditions must be favorable for subcooling charging.Favorable conditions exist when the outdoor temperature isbetween 70_F and 100_F (21.11_C and 37.78_C), and the indoortemperature is between 70_F and 80_F (21.11_C and 26.67_C).Follow the procedure below:Unit is factory charged for 15ft (4.57 m) of lineset. Adjust chargeby adding or removing 0.6 oz/ft of 3/8 liquid line above or below15ft (4.57 m) respectively.For standard refrigerant line lengths (80 ft/24.38 m or less), allowsystem to operate in cooling mode at least 15 minutes. If conditionsare favorable, check system charge by subcooling method. If anyadjustment is necessary, adjust charge slowly and allow system tooperate for 15 minutes to stabilize before declaring a properlycharged system.If the indoor temperature is above 80_F (26.67_C), and theoutdoor temperature is in the favorable range, adjust system chargeby weight based on line length and allow the indoor temperature todrop to 80_F (26.67_C) before attempting to check system chargeby subcooling method as described above.If the indoor temperature is below 70_F (21.11_C), or the outdoortemperature is not in the favorable range, adjust charge for line setlength above or below 15ft (4.57 m) only. Charge level should thenbe appropriate for the system to achieve rated capacity. The chargelevel could then be checked at another time when the both indoorand outdoor temperatures are in a more favorable range.NOTE: If line length is beyond 80 ft (24.38 m) or greater than 20ft (6.10 m) vertical separation, See Long Line Guideline forspecial charging requirements.Final ChecksIMPORTANT: Before leaving job, be sure to do the following:1. Ensure that all wiring is routed away from tubing and sheetmetal edges to prevent rub--through or wire pinching.2. Ensure that all wiring and tubing is secure in unit beforeadding panels and covers. Securely fasten all panels andcovers.3. Tighten service valve stem caps to 1/12--turn past fingertight.4. Leave Owner’s Manual with owner. Explain system opera-tion and periodic maintenance requirements outlined inmanual.5. Fill out Dealer Installation Checklist and place in customerfile.TROUBLESHOOTINGIf the compressor fails to operate with a cooling call, the tablebelow (Resistance table) can be used to verify if there is anydamage to the compressor windings causing system malfunction.Table 3 – Winding ResistanceWindingWinding resistance at 70_F +/--- 20_F(21.11_C +/--- 11.11_C)24ACB724 24ACB736 24ACB748 24ACB760Start(S ---C) 1.64 1.52 1.86 1.63Run(R---C) 1.30 0.88 0.52 0.39Troubleshooting 24ACB7 units for proper switchingbetween low-- and high--stagesCheck the suction pressures at the service valves. Suction pressureshould be reduced by 3--10% when switching from low to highstage.NOTE: The liquid pressures are very similar between low-- andhigh-- stage operation, so liquid pressure should not be used fortroubleshooting.Compressor current should increase 20 to 45% when switchingfrom low to high stage. The compressor solenoid when energizedin high stage, should measure 24vac at the leads inside control box.When the compressor is operating in low stage, the 24v DCcompressor solenoid coil is de--energized. When the compressor isoperating in high stage, the 24v DC solenoid coil is energized.The solenoid plug harness that is connected to the compressor hasan internal rectifier that converts the 24v AC signal to 24v DC.DO NOT INSTALL A PLUG WITHOUT AN INTERNALRECTIFIER.Unloader Test Procedure:The unloader is the compressor internal mechanism, controlled bythe DC solenoid, that modulates between high-- and low--stage. Ifit is suspected that the unloader is not working, the followingmethods may be used to verify operation:1. Operate the system and measure compressor amperage.Cycle the unloader on and off at 30 second plus intervals atthe thermostat (from low-- to high--stage and back to low--stage). Wait 10 seconds after staging to high before taking areading. The compressor amperage should go up or down atleast 20 percent.2. If step one does not give the expected results, remove thesolenoid plug from the compressor and, with the unit run-ning and the Thermostat calling for high--stage, test thevoltage output at the plug with a DC voltmeter. The readingshould be 24 volts DC.3. If the correct DC voltage is at the control circuit moldedplug, measure the compressor unloader coil resistance. Theresistance should be approximately 330 or 1640 ohms de-pending on unloader coil supplier. If the coil resistance isinfinite or is grounded, the compressor must be replaced.24ACB7