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Table 12. AHC Single Character Display Alert Codes (Communicating and Non−Communicating)
Alert Code
Status of Air Handler
Device communications problem − No other devices on BUS (Communication system).
No 60 hertz power (Check voltage and frequency)
Low 24 volts (18 or less volts) − Control will restart if the error recovers.
Unresponsive Device2 − Indicates a device on the RSbus is not responding to a message sent to it by another device.
Error code is applicable to all communicating devices on the RSbus (thermostat, indoor and outdoor units). Normally
indicates a malfunctioning device.
Active Subnet Controller Missing for > 180 seconds. This indicates a data connection has been lost between a commu-
nicating device and the communicating thermostat. Device (indoor or outdoor unit) sends the alarm if no communica-
tion is established between device and thermostat within three minutes.
Configuration jumper(s) is missing on AHC.
Non−volatile data corruption.
Failed Flash CRC check.
Outdoor air temperature sensor (OAS) out of range.
Indoor Blower communication failure − (includes indoor blower power outage)
Incorrect air handler model size and capacity selected or wrong motor. Check for proper configuring under
Configuring
Unit Size Codes
.
No air handler model size and capacity selected. Check for proper configuring under
Configuring Unit Size Codes
.
Indoor blower motor unable to start (seized bearing, stuck wheel, etc.).
Indoor blower motor over temperature (motor trip on internal protector)
Discharge air temperature sensor (DATS) out of range.
Restricted airflow Indoor blower motor is running at a reduced CFM (cutback mode **)
Indoor and outdoor unit capacity mismatch.
Global network connection error. This usually indicates there is a short or overladed resistance is to low) condition
between communicating indoor and thermostat units.
Jumper for second−stage cooling not removed.
Jumper for heat pump operation not removed.
Relay Y1 failure.
Relay Y2 failure.
Heat call with non−configured or mis−configured electric heat. Check for proper configuring under
Configuring Electric
Heat Stages
.
Heat section / Stage 1 failed (Pilot relay contacts did not close or the relay coil in electric heat did not energizing)
Heat section / Stage 2 failed.
Heat section / Stage 3 failed.
Heat section / Stage 4 failed.
Heat section / Stage 5 failed.
Defrost out−of−control
Error codes 401 through 409 are only displayed when the Control’s L terminal is connected to a non−communicating outdoor unit’s LSOM device..
Compressor ran more than 18 hours in air conditioning mode.
Compressor system pressure trip.
Compressor short−cycling − running less than four minutes.
Compressor rotor locked.
Compressor open circuit.
Compressor open start circuit.
Compressor open run circuit.
Compressor contactor is welded.
Compressor low voltage.
** Cutback Mode The variable speed motor has pre−set speed and torque limiters to protect the motor from damage caused by operating out of its
designed parameters (0 through 0.80 in. w.g. total external static pressure).
