Bryant 576b Start-Up I. Start-Upand Adjustments, A. Checking Cooling Control Operation

START-UP

I. START-UP AND ADJUSTMENTS

CAUTION: Complete the required procedures given in the Pre-Start-Up section and unit start-up checklist at the end of this publication before starting the unit. Do not jumper any safety devices when oper- ating the unit.

Do not operate the compressor when the outdoor tem- perature is below 25 F (24 C) (unless accessory low ambient kit is installed).

A. Checking Cooling Control Operation

Start and check the unit for proper cooling control operation as follows:

1.Place room thermostat SYSTEM switch in OFF posi- tion. Observe that blower motor starts when FAN switch is placed in ON position and shuts down when FAN switch is placed in AUTO. position.

2.Place SYSTEM switch in COOL position and FAN switch in AUTO. position. Set cooling control below room temperature. Observe that compressor and con- denser- and evaporator-fan motors start. Observe that cooling cycle shuts down when control setting is satisfied.

B.Unit Controls

All units have the following internal-protection controls:

Compressor Overload

This overload interrupts power to the compressor when either the current or internal motor winding temperature become excessive, and automatically resets when the inter- nal temperature drops to a safe level. This overload may require up to 60 minutes (or longer) to reset. If the internal overload is suspected of being open, disconnect the electrical power to the unit and check the circuit through the overload with an ohmmeter or continuity tester.

Time Guard® II Device

The unit is equipped with accessory Time Guard II recycle timer. The device will cause a 5-minute delay between com- pressor starts.

Cycle-LOC™ Device

When high-pressure or low-pressure fault occurs, the Cycle- LOC device will protect the system by not allowing the com- pressor to start.

Low-Pressure Switch/(LPS)

When the suction line pressure drops below 7 psig (48 kPa), the LPS opens 24-v power to the compressor contactor and stops the compressor. When the pressure reaches 22 psig (152 kPa), the switch resets and the compressor is allowed to restart.

High-Pressure Switch (HPS)

When the refrigerant high-side pressure reaches 426 psig (2937 kPa), the HPS opens 24-v power to the compressor con- tactor and stops the compressor. When the pressure drops to 320 psig (2206 kPa), the switch resets and the compressor is allowed to restart.

C. Sequence of Operation

At start-up, the thermostat calls for cooling. When all safety devices are satisfied, the compressor contactor (fan contactor) will energize causing the compressor and outdoor (condenser) fan motor to operate. Terminal “G” at the

thermostat is also energized, allowing the field-supplied and -installed (24v) indoor (evaporator) fan contactor to func- tion. A field-supplied and -installed liquid line valve (con- nected between Terminals G and C at the outdoor unit), will also open. This allows the system to function in cooling; the LPS will not open if compressor is not running. As cooling demand is satisfied, the thermostat contacts break, deener- gizing the contactor causing the system to shut off. The liq- uid line solenoid (LLS) valve closes, minimizing the potential for refrigerant migration at this time. The compressor does not restart until the thermostat again calls for cooling. If a demand for cooling occurs within 5 minutes after the ther- mostat is satisfied, the system will not restart due to the fea- ture of Time Guard II device. After the 5-minute time period, the system will restart as normal upon thermostat demand.

The system is protected with a Cycle-LOC device so that the compressor will not start if a high-pressure or low-pressure fault occurs. To reset the Cycle-LOC device, set the thermo- stat to eliminate the cooling demand then return to the orig- inal set point. This should be done only once, and if system shuts down due to the same fault, determine the problem before attempting to reset the Cycle-LOC device.

The crankcase heaters must be energized for a minimum of 24 hours before starting a 569C and 576B unit.

D. Oil Charge

576B Units

Allow unit to run for about 20 minutes. Stop unit and check compressor oil level. Add oil only if necessary to bring oil into view in sight glass. Use only approved compressor oil.

Approved oils are:

Suniso 3GS

WF32-150

If oil is added, run unit for an additional 10 minutes. Stop unit and check oil level. If level is still low, add oil only after determining that piping system is designed for proper oil return and that system is not leaking oil.

569C Units

The 569C units do not have a sight glass and are factory charged with the correct amount of oil.

All Units

Do not reuse drained oil or use any oil that has been exposed to the atmosphere. Procedures for adding or removing oil are given in the Standard Service Techniques Manual, Chapter 1, Refrigerants.

CARE AND MAINTENANCE

To ensure continuing high performance and to minimize the possibility of premature equipment failure, periodic mainte- nance must be performed on this equipment. This cooling unit should be inspected at least once each year by a quali- fied service person.

NOTE TO EQUIPMENT OWNER: Consult your local dealer about the availability of a maintenance contract.

WARNING: The ability to properly perform main- tenance on this equipment requires certain expertise, mechanical skills, tools, and equipment. If you do not possess these, do not attempt to perform any mainte- nance on this equipment other than those procedures recommended in the User’s Manual. FAILURE TO HEED THIS WARNING COULD RESULT IN SERI- OUS PERSONAL INJURY AND POSSIBLE DAM- AGE TO THIS EQUIPMENT.

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