Alarms and Troubleshooting
104 OAU-SVX007A-EN
Digital Scroll Compressor Controller
Units with digital scroll compressor controller provides control,
protection, and diagnostics for the digital compressor system.
It also modulates or cycles the unloader solenoid in an ON/
OFF pattern based on capacity demand signal from the system
controller.
POWER LED (Green) - Voltage is present at the 24VAC power
terminals. When the anti-short cycle timer is active, the green
LED will flash.
UNLOADER LED (Yellow) - Unloader solenoid status. This
LED is ON when the unloader solenoid is energized.
ALERT LED (Red) - Communicates an abnormal system
condition through a unique flash code. The ALERT LED will
flash a number of times consecutively, pause and then repeat
the process. The number of consecutive flashes, defined as
the flash code (Table 20), correlates to a particular abnormal
condition.
While each ALERT code is active, the alarm relay contacts (A1
and A2) are closed. The ALERT code will remain active, and
the alarm relay contacts closed until the reset conditions have
been met or 24VAC power has been cycled OFF and ON. All
flash codes except code 6 and 8 result in the compressor
contactor, unloader solenoid and vapor injection solenoid
being deenergized. Flash codes 3, 4, 5, and 9 activate the 2-
minute anti-cycle timer. Flash code 2 activates the 30-minute
timer. All LEDs flashing at the same rate indicates 24VAC
supply is too low for operation.
All LEDs on solid at the same time indicate digital scroll
compressor controller failure.
Whenever power is cycled OFF and ON, the current flash code
and all internal counters are reset.
Variable Speed Compressor Drive
Units with variable speed compressor drive deliver maximum
machine performance with sensor less permanent magnet
motor control, for dynamic and efficient machine operation.
Table 19. Mitsubishi VFD programming parameters
575V
Parameter Setting Description
1 Max Hz Maximum Frequency
2 Min Hz Minimum Frequency
7 30 s Acceleration Time
8 30 s Deceleration Time
9 Motor FLA Electronic Thermal O/L Relay
38 Max Hz Maximum Frequency
39 Max Hz Maximum Frequency
67 5 Number of Retries at Fault Occurrence
71 3 Applied Motor
73 1 Analog Input Selection
152 6 % Zero Current Detection Level
153 1 s Zero Current Detection Time
190 0 RUN Terminal Function Selection
79 2 Operative Mode Selection
77 1 Parameter Write Selection
Figure 147. Digital scroll compressor controller
Table 20. Digital scroll compressor controller flash code
details
Trouble Possible Cause
Digital Scroll Compressor
not running.
Compressor limit switch(es) open.
Compressor limit switch(es) open.
Minimum on/off time.
Refer to digital scroll controller alarm flash code.
Digital Scroll Compressor Controller Alert Flash Codes
Code 1 Reserved for future use.
Code 2 High Discharge Temperature.
Code 3 No current when compressor should be running.
Code 4 Locked Rotor.
Code 5 Normal operation when compressor is disabled.
Code 6 Thermistor Fault. Thermistor is not connected.
Code 7 Revere for future use
Code 8
Current is detected when compressor should be
OFF.
Code 9
Supply voltage to controller dropped below 18.5
VAC.
Figure 148. Variable speed compressor HOA-keypad
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