Bryant 583B manual Controls, 26, Operating Sequence

CONTROLS

OPERATING SEQUENCE

Heating — On a call for heating, terminal “W” of the thermostat is energized, starting the induced-draft motor. When the hall- effect sensor on the induced-draft motor senses that it has reached the required speed, the burner sequence begins. This function is performed by the integrated gas control (IGC). The evaporator fan motor is energized 45 seconds after flame is es- tablished. When the thermostat is satisfied and “W” is de- energized, the burners stop firing and the evaporator fan motor shuts off after a 45-second time-off delay.

Cooling — When the room temperature rises to a point that is slightly above the cooling control setting of the thermostat, the thermostat completes the circuit between thermostat terminal R to terminals Y and G. These completed circuits through the ther- mostat connect contactor coil (C) (through unit wire Y) and blow- er relay coil (BR) (through unit wire G) across the 24-v secondary of transformer (TRAN).

The normally open contacts of energized contactor (C) close and complete the circuit through compressor motor (COMP) to con- denser (outdoor) fan motor (OFM). Both motors start instantly.

The set of normally open contacts of energized relay BR close and complete the circuit through evaporator blower (indoor) fan motor (IFM).

NOTE: Once the compressor has started and then has stopped, it should not be started again until 5 minutes have elapsed.

The cooling cycle remains “on” until the room temperature drops to a point that is slightly below the cooling control setting of the room thermostat. At this point, the thermostat “breaks” the circuit between thermostat terminal R to terminals Y and G. These open circuits de-energize contactor coil C and relay coil BR. The condenser and compressor motors stop. After a 30-second de- lay, the blower motor stops. The unit is in a “standby” condition, waiting for the next “call for cooling” from the room thermostat.

The ICM FIOP indoor blower operation with a call for fan oper- ation (G) in cooling mode will perform by the on/off delay profile selected on the Easy Select™ circuit board.

— 26—