Unit installation

IOMM ACZ1-2 ACZ 010A through 039A 29
Dynamic Default Values
Some setpoints will have different default values loaded depending on the value of other
setpoints.
Low Evaporator Pressure Inhibit
Refrigerant Default Value
R22 59 psi
R407C 60 psi
Low Evaporator Pressure Unload
Refrigerant Default Value
R22 58 psi
R407C 59 psi
Equipment Protection (Stop) Alarms
Equipment protection (stop) alarms execute rapid compressor shutdown without going
through the normal shutdown cycle.
The following table identifies each of these alarms, gives the condition that causes the
alarm to occur, and states the action taken because of the alarm. If the alarm is auto-
clearing, the reset condition is shown below. Otherwise, the alarm is manually reset,
requiring the operator to clear the alarm.
Table 11, Stop Alarms
Description Occurs When: Action Taken Reset
No Evaporator (Water/Air)
Flow
Any compressor is running AND
Evap Flow Digital Input = No Flow for time >
Evap Flow Proof SP
Rapid Stop
Evap flow switch
closes OR Unit
State=Off
Low Evaporator Pressure
Evaporator Press < Low Evap Pressure SP
for time> Low Evap Pressure Time Delay
Rapid Stop Manual
High Condenser Pressure
Condenser Press > High Condenser
Pressure SP
Rapid Stop Manual
Motor Protection
Digital Input = High Motor Temperature
AND Delay 150 Sec. after power up has
passed
Rapid Stop Manual
Phase Voltage Protection
(opt)
If Phase Voltage Protection = Y, Then Digital
Input = Phase/Voltage Problem
Rapid Stop
Phase/Voltage
input returns to
normal
Low Ambient Restart Fault
Failed three consecutive low ambient start
attempts
Rapid Stop Manual
Evaporator Pressure
Sensor Fault
Sensor shorted or open Rapid Stop Manual
Condenser Pressure
Sensor Fault
Sensor shorted or open Rapid Stop Manual
Outside Ambient
Temperature Sensor Fault
Sensor open or shorted Normal Stop Manual
Evaporator Freezestat
Freezestat logic allows the circuit to run for varying times at low pressures. The lower the
pressure, the shorter the time the compressor can run. This time is calculated as follows:
Freeze error = Low Evaporator Pressure Unload – Evaporator Pressure
Freeze time = 60 – 1.6 x freeze error, limited to a range of 20-70 seconds
When the evaporator pressure goes below the Low Evaporator Pressure Unload setpoint, a
timer starts. If this timer exceeds the freeze time, then a freezestat trip occurs. If the
evaporator pressure rises to the unload setpoint or higher, and the freeze time has not been
exceeded, the timer will reset.