Hussmann Proto-Aire, Installation Manual, Page: 118 / 124

Protocol™ Installation and
Service Manual
Step 2 Proceed to the Status Menu for this Protocol™. Observe the operation of
compressors turning ON, and watch for suction pressure to come down. If
the suction pressure does not come down when a compressor comes on, it is
an indication that some external device is keeping the compressors off line
(high pressure safety, oil safety, phase monitor, etc.) You will need to go to
this Protocol™ and investigate whether or not compressors are running.
Alarm: Low Suction Pressure
This alarm is one of the three “switchback” alarms (See the paragraph describing
switchback). The time delay for this condition is 30 minutes. Low suction pressures are
ignored during defrost.
Possible Causes:
Low Refrigerant Charge
Low Alarm Limit is Not Set Properly
Step 1 Enter the Alarm Menu. Observe the time and date of the alarm. You will
be prompted as to whether or not you want to clear the current alarm. Press
the DEL key to remove the current alarm condition.
Step 2 Proceed to the Protocol™. Observe the operation of compressor turning
ON, as indicated by X’s. The Protocol™ should begin to operate the
compressors and suction pressure should be maintained. If this does not
occur you will need to further investigate the Protocol™ operation.
Alarm: All Compressors Off
This alarm is one of the three “switchback” alarms (See the paragraph describing
switchback). The time delay for this condition is 60 minutes. When the electronic control
has not turned on a compressor for one hour, this alarm will be triggered. This condition
exists when the suction pressure, as read by the electronic control is above the low alarm
limit and below the suction pressure setpoint.
Possible Causes:
An external influence has turned ON one or more compressors
Faulty reading from the pressure transducer
Step 1 Enter the Alarm Menu. Observe the time and date of the alarm. You will
be prompted as to whether or not you want to clear the current alarm.
Step 2 Proceed to the Protocol™. Observe the operation of compressors turning
ON, as indicated by X’s. The Protocol™ should begin to operate the
compressors and suction pressure should be maintained. If this does not
occur you will need to further investigate the Protocol™ operation
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