Bryant 551A operation manual XII. Relief Devices, XIII. Control Circuit, XIV. Replacement Parts

E. Freeze Protection Thermostat (FPT)

An FPT is located on the top and bottom of the evaporator coil. It detects frost build-up and turns off the compressor, allowing the coil to clear. Once the frost has melted, the com- pressor can be reenergized.

XII. RELIEF DEVICES

All units have relief devices to protect against damage from excessive pressures (e.g., fire). These devices protect the high and low side.

XIII. CONTROL CIRCUIT, 24-V

This control circuit is protected against overcurrent by a 3.2-amp circuit breaker. Breaker can be reset. If it trips, determine cause of trouble before resetting. See Fig. 36 and 37.

XIV. REPLACEMENT PARTS

A complete list of replacement parts may be obtained from any Bryant distributor upon request.

XV. ECONOMI$ER LEDs

The EconoMi$er control module has LEDs for diagnostic purposes. The flash code identification is shown in Table 17.

XVI. OPTIONAL HINGED ACCESS DOORS

When the optional service package is ordered or the if the hinged access doors option is ordered, the unit will be pro- vided with external and internal hinged access doors to facil- itate service.

Four external hinged access doors are provided. All external doors are provided with 2 large 1/4 turn latches with folding bail-type handles. (Compressor access doors have one latch.) A single door is provided for filter and drive access. One door is provided for control box access. The control box access door is interlocked with the non-fused disconnect which must be in the OFF position to open the door. Two doors are provided for access to the compressor compartment.

Two internal access doors are provided inside the filter/drive access door. The filter access door (on the left) is secured by 2 small 1/4 turn latches with folding bail-type handles. This door must be opened prior to opening the drive access door. The drive access door is shipped with 2 sheet metal screws holding the door closed. Upon initial opening of the door, these screws may be removed and discarded. The door is then held shut by the filter access door, which closes over it.

LEGEND AND NOTES FOR FIG. 36 AND 37

AHA — Adjustable Heat Anticipator BRK W/AT — Breaks with Amp Turns

C— Contactor, Compressor

CAP — Capacitor

CB — Circuit Breaker

CC — Cooling Compensator

CH — Crankcase Heater

CLO — Compressor Lockout

COMP — Compressor Motor

CR — Control Relay

DAT — Discharge Air Thermistor

DM — Damper Motor

DU — Dummy Terminal

EC — Enthalpy Control EQUIP — Equipment

FL — Fuse Link

FPT — Freeze Protection Thermostat

FU — Fuse

GND — Ground

		LEGEND
HC	— Heater Contactor		TB	— Terminal Block
HPS	— High-Pressure Switch		TC	— Thermostat Cooling
HTR	— Heater		TH	— Thermostat Heating
IFC	— Indoor-Fan Contactor		TRAN — Transformer
IFCB — Indoor-Fan Circuit Breaker				Terminal (Marked)
IFM	—	Indoor-Fan Motor
IFR	— Indoor-Fan Relay			Terminal (Unmarked)
L	—	Light
LPS	— Low-Pressure Switch			Terminal Block
LS	—	Limit Switch
NEC — National Electrical Code				Splice
OAT	—	Outdoor-Air Thermostat
OFC — Outdoor-Fan Contactor				Factory Wiring
OFM —		Outdoor-Fan Motor
				Field Wiring
OP	—	Overcurrent Protection
PL	— Plug Assembly			Option/Accessory Wiring
PRI	—	Primary
				To indicate common potential
QT	—	Quadruple Terminal
SW	—	Switch		only; not to represent wiring.

NOTES:

1.Compressor and/or fan motor(s) thermally protected; 3-phase motors protected against primary single-phasing conditions.

2.If any of the original wire furnished must be replaced, it must be replaced with type 90° C wire or its equivalent.

3.Jumpers are omitted when unit is equipped with EconoMi$er.

5.IFCB must trip amps is equal to or less than 140% FLA.

6.The CLO locks out the compressor to prevent short cycling on compressor over- load and safety devices. Before replacing CLO, check these devices.

7.Number(s) indicates the line location of used contacts. A bracket over (2) numbers signifies a single-pole, double-throw contact. An underlined number signifies a normally closed contact. Plain (no line) number signifies a normally open contact.

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