Carrier 69NT20-531-300 manual Precheck Procedure

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6.20.1 Precheck Procedure

a. Check unit for abnormal operation.

b. Check charge. If refrigerant is low repair as required and again check operation.

c. If sufficient capacity cannot be maintained or unit is tripping excessively on high pressure switch (HPS) in high ambients, check coils and clean if required.

d. If capacity or control cannot be maintained turn unit OFF, then back ON. This will reset the valve in the event the controller lost communication with the valve, and may correct the problem.

NOTE

Carefully listen to the valve. During reset, the valve will make a ratcheting noise that may be heard or felt as it is attempting to close. If this can be heard or felt, it indicates that the control- ler and drive module are attempting to close the valve, and may serve as a quick indication that the drive is in working order.

e.Operation of the valve may be checked using the con- troller valve override program, function code Cd41. Refer to paragraph 6.19 for valve override test in- structions.

6.20.2Checking The Stepper valve a. Checking with ohmmeter

Disconnect the four pin connector to the stepper SMV. With a reliable digital ohmmeter, check the winding resistance. In normal ambient, the valve should have 72 to 84 ohms measured on the red/green (a-b terminals) and on the white/black (c-d terminals) leads. If an infinite or zero reading occurs, check connections and replace the motor.

b. Checking with SMA-12 portable stepper drive tester

The SMA-12 portable stepper drive tester (Carrier Transicold P/N 07-00375-00) is a battery operated stepper drive which will open and close the SMV, which allows a more thorough check of the operating mechanism.

To check operation:

1.Stop the unit, disconnect the four pin connector from the stepper module to the valve (see Figure 6-17) and attach the SMA-12 stepper drive to the connector go- ing to the valve.

2.Set the SMA-12 pulse per second (PPS) to one PPS and either open or close valve. Each LED should light sequentially until all four are lit. Any LED fail-

ing to light indicates an open on that leg which indi- cates a poor connection or an open coil. Repair or re- place as required to achieve proper operation.

CAUTION

The scroll compressor achieves low suction pressure very quickly. Do not operate the compressor in a deep vacuum, internal dam- age will result.

3.Restart unit, set the step rate to 200 PPS on SMA-12 for the valve, and close stepper valve while watching the suction gauge. Within one minute the suction pressure will go into a vacuum. This is an indication that the valve is moving.

4.If no change in suction pressure is detected, check for resistance (refer to step 6.20.2), and check con- nections for proper continuity and retest. If the valve is functioning and all connections and motor resist- ance are good, check the controller and expansion module.

CAUTION

DO NOT disassemble piston from NEW suc- tion modulating valve powerhead assembly. Doing so may result in damage to piston.

5.If the valve is determined as faulty after completing the above steps, perform a low side pump down. Re- move valve powerhead assembly, and replace with a NEW valve powerhead assembly, torque nut to 35 ft- lb, evacuate low side, and open all service valves.

6.21CONTROLLER AND EXPANSION MODULE 6.21.1 Handling Modules

CAUTION

Do not remove wire harnesses from module unless you are grounded to the unit frame with a static safe wrist strap.

CAUTION

Unplug all module connectors before per- forming arc welding on any part of the con- tainer.

The guidelines and cautions provided herein should be followed when handling the modules. These precautions and procedures should be implemented when replacing a module, when doing any arc welding on the unit, or when service to the refrigeration unit requires handling and removal of a module.

T-309

6-14

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Contents Service Model Safety Summary 309 Safety-2 Safety-3 309 Table of Contents Table of Contents Connect Remote Monitoring Check Controller Function CodesReplacing The Evaporator Fan Assembly Valve ReplacementEvaporator Coil Replacement Evaporator Heater Replacement Precheck Procedure Checking The Stepper valveElectrical Wiring Schematic Refrigeration Circuit Schematic Standard Operation Refrigeration Circuit Schematic Economized OperationDataCORDER Configuration Variables List of TablesSection Introduction Unit is fitted with a scroll compressorManual, T-300 Section Description Evaporator Section Compressor Section Condenser Section Module which allow communication with a master Communications interface module For further informationApproved Oil Mobil ST32 Oil Charge 2957 ml 100 ounces Model RSH105 Weight Dry 46.5 kg 103 lbTemperature Oil level range, with the compressor offElectrical Data Safety and Protective Devices Refrigeration Circuit 2.5.1 Standard Operation Standard Operation with Receiver Refrigeration Circuit Schematic -- Economized Operation Temperature Control System Section MicroprocessorKEY Function Controller Software Modes of Operation Perishable Mode -- Economy Controller Alarms Unit PRE-TRIP Diagnostics DCF02=5 Usda thermistor inputs Thermistor inputssupply & returnDCF02=2 DCF02=6Standard Configuration Download Report Raw Data Report for ABC1234567DataCORDER may be powered up in any one of four ways Logging Interval dCF03DataView DataCORDER Alarms CnF33 Snap Freeze Option CnF11 Defrost Off Selection NoOFFStd, Full SnAPDisplay Only Functions Sensor Reading Defrost temperature sensor reading is displayedPossibly delaying a needed defrost cycle Plicable with frozen set pointsController Function Codes Sheet 3 Controller Alarm Indications Sheet 1 Controller Alarm Indications Sheet 2 Controller Alarm Indications Sheet 3 Error Description Memory failureDraw test is done after 10 seconds Draw test is done after 15 secondsP1-1 OndsP6-2 Supply is comparedTest fails Crease, the test failsDenser fan is started and a 60 second timer is started Pressure switch is open or the condenser fan switch is openTimer is started Requirements Control temperature must be at least 15.6C 60FRequirements Control temperature must be at least 7.2C 45F Set point, the test proceeds to testBy starting P10-0 over Inapplicable Functions Display Title Data 10 DataCORDER Alarm Indications Operation 69NT Fresh AIR MakeupWill be displayed To start a pre-trip test, do the followingWill be displayed Controller Operation -- Perishable Mode Pull Down Falling RisingController Operation -- Frozen Mode Frozen Mode Defrost Section Troubleshooting Unit will not heat or has insuffi Will not initiate defrost Bent motor shaftSuperheat Unit reads abnormal currents Current sensor wiring Check Section Service Valve Frontseated BackseatedCompressor in a deep vacuum, internal dam- age will result Refrigerant Leak Checking Remove all refrigerant using a refrigerant recovery system Refrigerant Charge Compressor Upper Mounting Compressor OIL Level Condenser FAN and Motor Assembly Two expansion valves are used, the evaporator Wrapped with Insulating compound. SeeRemoving the Expansion Valve Equalizer line Cleaned regularly. The preferred cleaning fluid is freshIf applicable, braze the equalizer connection to Check superheat refer to stepStart unit and check operation 14. Unloader Solenoid ValveEvaporator FAN Motor Capacitors Valve Override Controls Precheck Procedure TP1 Mounting Stud Type Shorter than the other wire Cut wires 5 cm 2 inches from shoulder of defecCut one wire of existing cable 40 mm 1-1/2 inch Cut one replacement sensor wire opposite colorMaintenance of Painted Surfaces 23 Door Hinge Repair Crack, Chip & Hole Repair Kit 24. Insert Location In-lbs #10 Ft-lbs 12.72 17.14 In-lbs Ft-lbs 13.99 18.8614.6 49.4 37.08 12.3 41.6 31.25 32.8 24.64 22.7 17.00 11.9 Section Electrical Wiring Schematic Schematic Diagram Wiring Diagram Sheet 1 Wiring Diagram Sheet 2 Index 309 Index-2

69NT20-531-300 specifications

The Carrier 69NT20-531-300 is a cutting-edge rooftop unit designed to meet the demanding requirements of commercial heating and cooling applications. This model embodies Carrier’s commitment to energy efficiency, reliability, and advanced technological features that enhance indoor comfort while minimizing operational costs.

One of the standout features of the Carrier 69NT20-531-300 is its high energy efficiency. It is equipped with advanced compressor technology that optimizes performance while reducing energy consumption. This ensures that businesses can maintain a comfortable indoor climate without incurring exorbitant utility bills. With a high Seasonal Energy Efficiency Ratio (SEER) and Energy Efficiency Ratio (EER), users can expect not only enhanced comfort but also significant cost savings over time.

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Overall, the Carrier 69NT20-531-300 stands out as a premier choice for businesses looking for an efficient, reliable, and feature-rich rooftop HVAC unit. Its blend of energy efficiency, advanced technology, and durability positions it as a leader in commercial heating and cooling solutions, making it a valuable investment for any commercial property.
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