IM 882 / Page 34 of 36
Fault code Description Cause for the fault
CE Communication Error 1. Cable not plugged in properly on either LUI or relay board.
2. Defective cable.
Sh Missing Shunt The user congurable shunt for System Select, Control Select Off Fan Cycle, and/or Hydronic Valve is
missing or not placed properly.
E1 Problem with IAS Indoor Air Sensor missing or short.
E2 Problem with ICS Indoor Coil Sensor missing or short.
E3 Problem with OCS Outdoor Coil Sensor missing or short.
E4 Problem with OAS Outdoor Air Sensor missing or short.
E5 Problem with HFLO Sensor HFLO Sensor missing or short on AP7809.
Protection
Description Cause for the fault
code
CF Coil Freeze Protection Indoor coil temperature has been below 30ºF for 5 minutes.
Protection feature and the displayed code are dismissed when indoor coil temperature rises above 49ºF.
Rf Room Freeze Protection Indoor air temperature has dropped below 41ºF. Protection feature and the displayed code are
dismissed when indoor room temperature rises at and above 50ºF.
hI High Room Temperature Indoor air temperature is 5 degrees above maximum setpoint limit. Protection feature and the displayed
code are dismissed when indoor coil temperature rises above 50ºF.
Lo Low Room Temperature Indoor air temperature is 5 degrees below minimum setpoint limit.
LA Low Ambient Lockout Outdoor air temperature is below 35ºF.
Fault and Protection Codes for Applied PTAC/PTHP Control Board
Fault code Description Cause for the fault
LC Control Lockout – Displays for 5 seconds when any button is pushed when in the "lockout mode".
nL Control Lockout – Displays for 5 seconds to conrm normal mode of operation when control lockout turned off.
Normal Control
CL Damper Closed Control setup indicator damper is in "closed" mode.
AU Auto Damper Control setup indicator damper is in "automatic" mode.
AU Auto HP/E Control setup indicator heat pump electric is in automatic changeover mode (HP/E).
bY HP/E Bypass Control setup indicator, electric heat is bypassed when OCS > 40˚.
CF Coil Freeze Protection Indoor coil is ≤ 30˚ for at least 5 minutes. Compressor and outdoor fan stop and indoor fan continues
to run for active defrost.
rF Room Freeze Protection Room temperature < 41˚. Damper closes (Premium board) and unit goes into heat mode.
Lo Coil freeze protection Room temperature is 5˚ below set point.
Hi Temperature Limiting Room temperature is 5˚ above set point.
LA Low Ambient Lockout Unit is in cooling mode and outdoor air < 35˚. Compressor will cut out.
E1 Indoor Air Sensor Indoor Air Thermister Failure.
E2 Indoor Coil Sensor Indoor Coil Thermister Failure.
E3 Outdoor Coil Sensor Outdoor Coil Thermister Failure.
E4 Outdoor Air Sensor Outdoor Air Thermister Failure.
Solid State Digital Controls – Local User Interface Display Codes
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