AAON CF Series - Compressor Controls and Operation; Variable Capacity Compressor Controller

45
When all is running properly, place the
controller in the Run mode and observe the
system until it reaches a steady state of
operation.
Compressor Operation
The compressors must be off for a minimum of
3 minutes and on for a minimum of 5 minutes.
Short cycling of the compressors can cause
undue stress and wear.
Microchannel Unit Restart Sequence
Units with microchannel condenser coils
include a sequence of controls to allow
additional compressor restarts without locking
out the high pressure switch on the
compressors. This helps with the startup
process when the microchannel coil is cold.
The sequence allows four high pressure trips
with auto reset within the first 15 minutes after
a compressor call, but will lock out the
compressors on the fifth high pressure trip.
After the first 15 minutes of operation, one
more restart is allowed, but the compressors
will lockout if another fault occurs within 2
hours.
Variable Capacity Compressor Controller
Units with variable capacity scroll
compressors may include a variable capacity
compressor controller. The following is an
explanation of the terminals and
troubleshooting of the alert flash codes on the
controller. For more information on the
compressor controller, see Emerson Climate
Bulletin AE8-1328.
Figure 13 - Variable Capacity Compressor
Controller
Note: When using field controls any variable
capacity compressors must run at 100% for 1
minute when starting.
Low Voltage Terminals
24COM Module Common
24VAC Module Power
C1 Demand Input -
C2 Demand Input +
P1 Pressure Common
P2 Pressure Input
P3 Pressure Power 5VDC
P4 Pressure Shield
P5 Pressure Output -
Before completing installation, a
complete operating cycle must be
observed to verify that all components
are functioning properly.
CAUTION
COMPRESSOR CYCLING
3 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 3 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 7
starts per hour.
WARNING