AAON CC-063 - Manual (Page 30)

30
Low Ambient Options
Adjustable fan cycling is a low ambient
head pressure control option that cycles the
condenser fans to maintain refrigerant
circuit head pressures at acceptable levels
during cooling operation. The head pressure
set point (100-470 psi) and pressure
differential (35-200 psi) are field adjustable.
Modulating fan pressure control is a low
ambient head pressure control option that
sends to an electronically commutated motor
a variable signal in relation to the refrigerant
circuit head pressure of the system. The
motor either speeds up or slows down air
flow accordingly in order to maintain
constant head pressure. Both head pressure
control options allow mechanical cooling
with ambient temperatures down to 35°F.
The AAON 0°F low ambient system
maintains normal head pressure during
periods of low ambient by effectively
reducing the heat transfer surface area,
reducing capacity and increasing condensing
pressure, allowing the system to operate
properly. During periods with higher
ambient temperatures the entire condenser is
required to condense refrigerant.
Maintenance
(See back of the manual for maintenance
log)
At least once each year, a qualified service
technician should check out the unit. This
includes reading and recording suction
pressures and checking for normal sub-
cooling and superheat.
Only Factory Trained Service Technicians
experienced in both condensing units and air
conditioning are permitted to service the CC
Series units to keep warranties in effect.
Coils
The condenser coils should be inspected
yearly to ensure unrestricted airflow. If the
coils contain a large amount of airborne dust
or other material, they should be cleaned.
Care must be taken to prevent bending of the
aluminum fins on the coils.
Before attempting to clean the coils; set
thermostat to the "OFF" position; turn the
electrical power to the unit to the "OFF"
position at the disconnect switch. The
condenser coil can be thoroughly cleaned by
washing from the inside out with water and
a coil cleaner. If coil is extremely dirty with
clogged
fins, a service professional
specializing in coil cleaning should be
called.
E-Coated Coil Cleaning
Documented routine cleaning of e-coated
coils is required to maintain coating
warranty coverage.
Surface loaded fibers or dirt should be
removed prior to water rinse to prevent
restriction of airflow. If unable to back wash
the side of the coil opposite of the coils
entering air side, then surface loaded fibers
or dirt should be removed with a vacuum
Improper installation, adjustment,
alteration, service or maintenance
can
cause property damage,
personal injury or loss of life. Startup
and service must be performed by a
Factory Trained Service Technician.
WARNING
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING