Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1

CMP IS RUNNING (14)

6.2.19.

For fixed capacity compressors only, this state occurs when the compressor is fully loaded. In this state,

the compressor is providing the maximum amount of cooling capacity.

FAST UNLOADING (15)

6.2.20.

For screw compressors only, this state is entered when the compressor is turned on. All load solenoids

will be turned off and all unload solenoids will be turned on to ensure the screw is fully unloaded. If an oil

pump is included in the system it will be turned on during this state. The time in this state is set in the “Fast

Unload Delay” cell under the Compressor Information button in the MAG V8 screen.

LO SUCT UNLOAD (16)

6.2.21.

Refer to Setpoints #77 “LOW SUCTION”; #78 “LO SUCT UNLD”; and #79 “LO SUCT RELD”.

For variable step compressors only. The capacity is being unloaded due to low suction pressure. The

compressor will stay in this state until the suction pressure is above Setpoint #79 “LO SUCT RELD”. The

system will then move to the LO SUCT HOLD state.

LO SUCT HOLD (17)

6.2.22.

Refer to Setpoints #77 “LOW SUCTION”; #78 “LO SUCT UNLD”; and #79 “LO SUCT RELD”.

Fixed step compressors - This state is entered when a fully loaded compressor that has more than one

step is unloading due to low suction pressure. One step of capacity is turned off. The compressor will

remain in this state for a minimum of five minutes before returning to the LOADED state if the low suction

condition has been corrected.

Variable Step Compressors - Capacity is being held due to low suction pressure. Once the suction

pressure returns to a normal operating level the compressor will return to its normal running state.

HI DISC UNLOAD (18)

6.2.23.

Refer to Setpoints #81 ”HI DISC PSI”; #82 “HI DISC UNLD”; #83 “HI DISC RELD”; #87 “HI DISC TMP”;

#88 “HI DISC UNLD”; #89 “HI DISC RELD”, and #84 “LO DISC SHEAT”.

For variable step compressors only. The capacity is being unloaded due to a high discharge pressure,

high discharge temperature, or low discharge superheat. The compressor will stay in this state until the

pressure or temperature has dropped below the corresponding Setpoint. The system will then move to the

HI DISC HOLD state.

HI DISC HOLD (19)

6.2.24.

Refer to Setpoints #81 ”HI DISC PSI”; #82 “HI DISC UNLD”; #83 “HI DISC RELD”; #87 “HI DISC TMP”;

#88 “HI DISC UNLD”; and #89 “HI DISC RELD”.

Fixed Step Compressors - This state is entered when a fully loaded compressor that has more than one

step is unloading due to high discharge pressure or temperature. One step of capacity will be turned off.

The compressor will remain in this state for a minimum of five minutes before returning to the LOADED

state if the high discharge condition has been corrected.