Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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If a variable step compressor, then the percentage wanted on will be checked. If it is less than
Setpoint #31 “MIN SLIDE %”, or option “Use Min FLA” has been selected, the percentage
wanted will be set to the value in Setpoint #31 “MIN SLIDE %” and the state will be set to
HOLDING.
Any associated EXV will be adjusted to allow for additional capacity.
If the compressor does not meet all of the conditions it will be LOCKED OUT and an error message will
be generated indicating the reason for the failure: pressure, temperature or time.
NOT USED (7) 6.2.8.
CMP UNLOADED (8) 6.2.9.
For variable step compressors, this state occurs when the slide is fully unloaded (indicated by unloaded
input or after the unloader is pulsed for 30 seconds with no change). For fixed step compressors, this
state occurs when the compressor is on and fully unloaded. In this state the compressor is supplying its
minimum cooling capacity.
CMP UNLD STEP1 (9) Only HVAC Software 6.2.10.
This state only applies for fixed step capacity compressors with a Hot Gas Bypass solenoid. In this state
the Hot Gas Bypass solenoid is off and all unloaders in the compressor are on.
CMP DECR SPEED (9) Only CENT Software 6.2.11.
In this state the compressor speed will be decreased.
CMP UNLD STEP2 (10) Only HVAC Software 6.2.12.
This state only applies for fixed step compressors with two unloaders. This state occurs when the Hot Gas
Bypass solenoid, if present, is off, the first unloader solenoid is off, and the second unloader solenoid is
on.
CMP INCR SPEED (10) Only CENT Software 6.2.13.
In this state the compressor speed will be increased.
CMP IS HOLDING (11) 6.2.14.
This state only applies for variable step compressors. In this state, the required refrigeration capacity of
system is being met; no movement of the slide valve is required.
CMP IS LOADING (12) Only HVAC Software 6.2.15.
For variable step compressors, this state occurs when the load solenoid is being pulsed to increase the
capacity of the compressor. The duration of the pulse is specified in the Setpoint #37 “LOAD PULSE” and
the frequency of the pulse is determined by Setpoint #56 “PULSE DELAY”. The Setpoint “PULSE
DELAY” should be a value of between 3 and 5 seconds to allow the amp sensor to reflect the change.
CMP OPEN VANES (12) Only CENT Software 6.2.16.
In this state the vanes are being opened because more capacity is required.
CMP IS UNLDING (13) Only HVAC Software 6.2.17.
For variable step compressors, this state is when the unload solenoid is being pulsed to reduce the
capacity of the compressor. The duration of the pulse is specified in Setpoint #38 “UNLOAD PULSE” and
the frequency of the pulse is determined by Setpoint #56 “PULSE DELAY”. The Setpoint “PULSE
DELAY” should be a value of between 3 and 5 seconds to allow the refrigerant to enter the chamber
slowly enough to not cause oil foaming.
CMP CLOSE VANES (13) Only CENT Software 6.2.18.
In this state the vanes are being closed because less capacity is required.