Form O-Y, PN 273647R5, Page 16
Option BE Pressure
Controller with ECM
Fan Option CUF4,
P/N 272460
3.0 Maintenance and Service Procedures - Unit & Cooling (cont'd)
3.5 Coils and Related Components (cont'd)
Low Ambient Control for standard condenser fans (Option BE8
with ECM Fan Option CUF4)
Fan(s) modulation from full speed occurs at 80°F liquid line, and reaches minimum
speed at 55°F liquid line. The ECM motor cycles "OFF" for all liquid line °F
temperatures of 55°F or below, and cycles "ON" at 58° liquid line. This differential
represents approximately 3°F condensing temperature variation. Matching these
operating parameters to your ECM motor may require specific customization. Consult
factory for more information.
Assuming a 200 RPM minimum speed, and 1,200 RPM full motor speed, the motor
cycles "OFF" at 200 RPM and back "ON" at 300 RPM and then modulates back
to 200 RPM before cycling off. The motor remains "OFF" for longer and longer
periods of time as the outdoor air ambient temperature continues to fall below 30°F.
Modulated minimum speed cycling continues until the requirement for cycling ends.
Low Ambient Control,
Option BE8
Install sensor(s) to the top of the liquid line where the line exits the condenser coil
as shown below in sketch. A liquid line sensor and head pressure controller will be
required for each independent refrigerant circuit. Units equipped with 2 sets of dual
condenser fans will require a head pressure controller and a liquid line sensor for
each set.
Low Ambient Control, Option BE8 (cont'd)
Installation of Liquid
Line Sensor(s)
