Bryant 661S, 661G, 661C instruction manual Sequence of Operation l, Phase Monitor Control

LEGEND

24-V FACTORY WIRING

24-V FIELD WIRING

FIELD SPLICE CONNECTION

ODT

	OUTDOOR THERMOSTAT
EHR	EMERGENCY HEAT RELAY
SHR	SUPPLEMENTAL HEAT RELAY

A97413

CAUTION: To prevent personal injury wear safety glasses, protective clothing, and gloves when handling refrigerant and observe the following:

•Back-seating service valves are not equipped with Schrader valves. Fully back seat (counterclockwise) valve stem before removing gage-port cap.

•Front-seating service valves are equipped with Schrader valves.

CAUTION: Do not vent refrigerant to atmosphere. Re- cover during system repair or final unit disposal.

1.Fully back seat (open) liquid- and vapor-tube service valves.

2.Unit is shipped with valve stem(s) front seated (closed) and caps installed. Replace stem caps after system is opened to refrigerant flow. Replace caps finger-tight and tighten with wrench an additional 1/12 turn.

3.Close electrical disconnects to energize system.

4.Set room thermostat to desired temperature. Be sure set point is below indoor-ambient temperature.

5.Set room thermostat to HEAT or COOL and fan control to ON or AUTO mode, as desired. Operate unit for 15 minutes. Check system-refrigerant charge.

CAUTION: • 3-phase scroll compressors are rotation sensitive.

•A flashing LED on phase monitor indicates reverse rotation. (See Fig. 10 and Table 3.)

•This will not allow contactor to be energized.

•Disconnect power to unit and interchange 2 field wiring leads on unit contactor.

A.Sequence of Operation l .

With power supplied to indoor and outdoor units, transformer is energized.

COOLING

On a call for cooling, thermostat makes circuits R-O, R-Y, and R-G. Circuit R-O energizes reversing valve, switching it to cooling position. On three phase models with scroll compressors, the units

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are equipped with a phase monitor to detect if the incoming power is correctly phased for compressor operation. (See Fig. 10 and Table 3.) If the phasing is correct, circuit R-Y energizes contactor, starting outdoor fan motor and compressor circuit. R-G energizes indoor unit blower relay, starting indoor blower motor on high speed.

NOTE: If the phasing is incorrect, the contactor will not be energized. To correct the phasing, interchange any two of the three power connections on the field side.

When thermostat is satisfied, its contacts open, de-energizing the contactor and blower relay. Compressor and motors should stop.

NOTE: If indoor unit is equipped with a time-delay relay circuit, the blower runs an additional 90 sec to increase system efficiency.

HEATING

On a call for heating, thermostat makes circuits R-Y and R-G. If phasing is correct, circuit R-Y energizes contactor, starting out- door fan motor and compressor. Circuit R-G energizes indoor blower relay, starting blower motor on high speed.

Should temperature continue to fall, R-W2 is made through second-stage room thermostat bulb. Circuit R-W2 energizes a sequencer, bringing on first bank of supplemental electric heat and providing electrical potential to second heater sequencer (if used). If outdoor temperature falls below setting of outdoor thermostat (field-installed option), contacts close to complete circuit and bring on second bank of supplemental electric heat.

When thermostat is satisfied, its contacts open, de-energizing contactor and sequencer. All heaters and motors should stop.

A00010

Fig. 10—Phase Monitor Control

DEFROST

The defrost control is a time/temperature control which includes a field-selectable (quick-connects located at board edge) time period between defrost cycles (30, 50, or 90 minutes), factory set at 90 minutes.

The electronic timer and defrost cycle start only when contactor energized and defrost thermostat is closed.

Defrost mode is identical to cooling mode except that outdoor fan motor stops and second-stage heat is turned on to continue warming conditioned space.

To initiate defrost, the defrost thermostat must be closed. This can be accomplished as follows:

1.Turn off power to outdoor unit.

2.Disconnect outdoor fan motor lead from OF2 on control board. (See Fig. 11.) Tape lead to prevent grounding.