www.DaikinApplied.com 41 OM 1263 • MICROTECH UNIT CONTROLLER
Defrost Temperature Sensor Problem (Heat
Pump only) – (DFT Sensor: Problem)
This alarm occurs when the DFT sensor input is shorted or open
circuited for the Sensor Alarm Delay (default 30 seconds). It can
also occur if the input is outside the range of -47°F to 194°F.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
Suction Line Refrigerant Temperature Sensor
Problem – (SRT Sensor: Problem)
This alarm occurs when the SRT sensor input is shorted or open
circuited for the Sensor Alarm Delay (default 30 seconds). It can
also occur if the input is outside the range of -47°F to 194°F.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
High Inverter Compressor Discharge Line
Temperature Problem – (Hi DL Temp: Problem)
This alarm occurs when the High Discharge Line Temperature
Unloading function has forced compressor operation to the
Standby state for a third time in a 100 minute period.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
Expansion Valve Problem – (Exp Valve:
Problem)
This alarm occurs when the IFB communication board detects
a faulty or disconnection between an expansion valve (EVI or
EVO) and the expansion valve control board (EVB).
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
NOTE: The EVB only detects a change in the EVI or EVO
condition upon power up of the EVB.
Outdoor Fan Problem – (OA Fan: Problem)
On a single outdoor fan unit this alarm occurs when compressor
operation is forced to the Standby state due to an outdoor fan
internal fault for a third time in a 30 minute period.
On a two outdoor fan unit this alarm occurs when compressor
operation is forced to the Standby state due an outdoor fan 2
internal fault for a third time in a 30 minute period. Note that
outdoor fan 2 in this conguration provides critical cooling for the
inverter/outdoor fan control boards.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
Low Refrigerant Charge Problem – (Lo Charge:
Problem)
During compressor cooling operation this alarm occurs when the
indoor expansion valve (EVI) is fully open (greater that 95%),
the super heat is well above set point (greater than 20°F) and
the lower of the two discharge line temperature inputs (DRT1
and DRT3) is hot (greater than 150°F) for more than 30 minutes
continuously.
During compressor heating operation this alarm occurs when the
outdoor expansion valve (EVO) is fully open (greater that 95%)
and the super heat is well above set point (greater than 20°F) for
more than 60 minutes continuously.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
Refrigerant Charge Loss Problem –
(ChargeLoss: Problem)
This alarm occurs when both the suction and discharge
line pressure inputs (PTS and PTD) remain below 10 psi
continuously for 5 seconds.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
Suction Line Refrigerant Pressure Sensor
Problem – (PTS Sensor: Problem)
This alarm occurs when the suction line pressure inputs (PTS)
remains above 256 psi continuously for 12 minutes or below -15
psi continuously for 10 seconds.
When this alarm is active compressor cooling and heating
operation are disabled.
The alarm must be manually cleared once corrective action is
taken.
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