Troubleshooting Tips... Before you call for service
Save time and money! Review the charts on the following pages first and you may not need to call for service.
Problem
The unit does not function
after installing Remote
Wall Thermostat
Heat pump operates with
electric heat only during
heating.
FAULT CODES - Press and hold MODE, then press AUX
This shows all current fault codes, and cycles through them. If there are no current faults, the display shows "--".
Pressing AUX clears the faults. Any other key exits and preserves the faults.
Fault Code
Fault Meaning
Numbers
1
Inside fan fault. Fan motor not moving at commanded speed after 90
seconds of drive. Fault clears after 10 minutes.
2
Outside fan fault. Fan motor not moving at command speed after 90
seconds of drive. Fault clears after 10 minutes.
3
External thermostat wiring. Applied signal is not valid and has been
constant for 30 seconds.
4
Inside thermistor fault. One of the inside thermistors is not reading valid
temperatures.
5
Outside thermistor fault.
One of the outside thermistors is not reading valid temperatures.
6
Compressor fault. No temperature change has been detected after 1
minute of running.
7
Reverse valve fault. Temperature change not happening as expected
after 1 minute of running.
8
Software fault. Stack overflow.
9
Indoor coil freeze fault. The temperature of the inside coil has fallen
below the freeze threshold (34ºF).
10
Heat pump overload fault. The inside coil temperature is over the
overload threshold (131°F).
11
Overheat fault. The incoming air is too hot to run the heater.
12
UI board disconnected/failed.
13
Heater airflow fault.
16
N/A
17
Outlet thermistor failure. Fault clears when thermistor reads value other
than short circuit or open circuit.
18
Outlet temperature overheat. The outgoing air is too hot. Fault clears
when air temperature drops below threshold.
19
Outlet temperature overheat. The outgoing air is too hot.
23
N/A
24
N/A
25
Abnormal Defrost Fault (heat pump models only). Set when 5 consecutive defrost
cycles failed to warm outdoor coil above 68°F. Will self clear after 4.5 days.
26
Air Conditioning Lockout Fault. Sets when outdoor ambient temperature drops
below 35ºF. Will self clear after Outdoor Ambient temperature rises above 40°F.
30
Possible Cause
Unit thermostat connections are incorrect.
Transformer resets or opens with short.
Outdoor ambient temperature is too cold.
Aux Mode 8 not set properly.
What To Do
Verify wiring from Remote Wall Thermostat is correct to unit
thermostat connector.
Wait 5 minutes to see if power resets.
Heat pump operation will not function if the outdoor ambient
temperature is too cold. Heat pump will resume once the
outdoor temperature has sufficiently warmed up
See "Setting the auxiliary control" section of this manual.
Check Aux Mode 8 to be sure the mode is set to OFF "U" for
heat pump operation.
Effective on system operation while
fault is active
No resistance heating, fan, heating
pump or cooling available.
No heat pump or cooling available.
Resistance heating and fan only.
No external control of fans, heat and
cooling internal control operation only.
No cooling or heat pump operation available.
Resistance heating and fan only.
No cooling or heat pump operation available.
Resistance heating and fan only.
No effect.
No cooling or heat pump operation available.
Resistance heating and fan only.
No effect.
The compressor is shut down until the
coil temperature recovers.
The compressor is shut down while the
coil temperature recovers.
Heat pump and resistance heating are
shut down and restarted when the indoor
ambient temperature cools sufficiently.
No effect.
No resistance heating available.
N/A
No resistance heating available.
No resistance heating available.
No resistance heating available.
N/A
N/A
Locks out heat pump, locks out defrost.
Locks out compressor cooling operation.
49-5000561 Rev. 1