Kold-Draft GB450A SERVICE MANUAL

SEQUENTIAL CIRCUIT DIAGRAM – GB450, GB650 & GT550 MODELS

Diagram #1 Water Fill—Evaporator Temperature Above 50°F.

Bin thermostat closed; Switch in “ice” position; Contactor closed; Water plate closed (pump & defrost switch up)

Liquid level control is low, actuator thermostat warm—power to the water valve. Pump and defrost switch up (water plate closed)—power to the
water pump. Cold water thermostat warm.

SEQUENTIAL CIRCUIT DIAGRAM – GB450, GB650 & GT550 MODELS

Diagram #2 Water Fill—Cold Water Thermostat Cycle (Evaporator Temperature Below 50°F.)

Bin thermostat closed; Switch in “ice” position; Contactor closed; Water plate closed (pump & defrost switch up)

Liquid level control is low, actuator thermostat warm—power to the water valve. Pump and defrost switch up (water plate closed)—power to the
water pump.

Cold water thermostat switches cold—power to defrost valve.

SEQUENTIAL CIRCUIT DIAGRAM – GB450, GB650 & GT550 MODELS

Diagram #3 Water Fill Complete—Evaporator Temperature Above 26°F.)

Bin thermostat closed; Switch in “ice” position; Contactor closed; Water plate closed (pump & defrost switch up)

Liquid level control high—power off to the water valve. Pump and defrost switch up (water plate closed)—power to the water pump. Actuator
thermostat is warm.

SEQUENTIAL CIRCUIT DIAGRAM – GB450, GB650 & GT550 MODELS

Diagram #4 Ice Forming—Evaporator Temperature Below 26°F.)

Bin thermostat closed; Switch in “ice” position; Contactor closed; Water plate closed (pump & defrost switch up)

Liquid level control high—power off to the water valve. Pump and defrost switch up (water plate closed)—power to the water pump. Actuator
thermostat switches cold.