Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
63
EXV Related Setpoints. 7.43.1.
(Refer to section 13 Setpoints 9-20, 65-72, 109-110, 199-201, 205, 215, 217, and 230)
These Setpoints were added to provide fine-tuning to the testing of the movement of the superheat
temperature. Refer to EXV control logic chart in a previous section.
EXV Control States 7.43.2.
The EXV Control States show the status of the compressor’s expansion valve. If the
compressor has an EXV it will be displayed under the Status entry.
To view the EXV status through the Keypad LCD, select Status from the Main Menu and then
page to the EXV screen.
EXV States:
LOCKED OUT
The compressor is in a Lockout state.
IS CLOSED
The associated compressor is OFF and the valve is closed
PRE-PMPDWN
The valve has been in a closed state and the system is now requiring the valve action.
IN STARTUP
At startup the valve will remain in this state for the time in Setpoint #20. At that time the state
will be changed to holding, at this point the valve control logic will position the valve.
AT 100%
This state will be entered when the valve opening reaches 100%.
IS HOLDING
Refer to EXV Logic Chart, superheat is in control zone and ROC is acceptable.
IS OPENING
Refer to EXV Logic Chart, superheat is in control zone but rising too fast, ROC less than 1.0.
IS CLOSING
Refer to EXV Logic Chart, superheat is in the control zone and the rate of change is
acceptable, ROC greater than –0.5.
LOW SPRHT
Refer to EXV Logic Chart, force a course valve adjustment.
OPENING 4x
Refer to EXV Logic Chart, superheat is above control zone.
OPENING 2x
Refer to EXV Logic Chart, superheat is in control zone but rising too fast, the ROC is greater
than 1.0.
LO PSI OPN
Refer to EXV Logic Chart, state indicates that a low suction pressure condition exists. The
suction pressure is less than Setpoint #77 “LOW SUCTION” plus twice the value of Setpoint
#79 “LOW SUCT RELOAD” and the superheat is greater than Setpoint #9 “SUPERHT TRGT”
plus twice the value of Setpoint #10 “SPRHT ZONE+-“.
CLOSING 2x
Refer to EXV Logic Chart, superheat is in the control zone and the rate of change is
acceptable, the ROC is less than -0.5 and greater than -1.0.
CLOSING 4x
Refer to EXV Logic Chart, superheat is in control zone but falling too fast, ROC less than -1.0.
HI LVL CLS
This state indicates that a high refrigerant level. This state is entered if Setpoint #109
“HiRefLevel” is active and the superheat is greater than the value of this Setpoint.
IS MOP CLS
Refer to EXV Logic Chart. Maximum operating pressure option is active and it is forcing the
EXV to close. In this state the EXV valve’s opening will be reduced.
IS MOP HLD
Refer to EXV Logic Chart. Maximum operating pressure option is active and it is forcing the
EXV to hold.