AAON CB-060 - Manual (Page 28)

28
Low Ambient Options
The condenser fan cycling option is used to
operate a refrigerant system down to 35°F
outside air temperature. As the ambient
temperature drops, the condenser becomes
more effective therefore lowering the head
pressure. When the head pressure gets too
low there will be insufficient pressure to
operate the expansion valve properly.
During low ambient temperatures, it is
difficult to start a system because the
refrigerant will migrate to the cold part of
the system (condenser) and make it difficult
for refrigerant to flow.
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 trained and qualified service
technicians experienced in both condensing
units and air conditioning are permitted to
service the CB 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 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
cleaner. If a vacuum cleaner is not available,
a soft non-metallic bristle brush may be
Improper installation, adjustment,
alteration, service or maintenance
can
cause property damage,
personal injury or loss of life.
Installation and service must be
performed by a trained, qualified
installer.
WARNING
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING