Fault
Code
Displayed
Fault Counts
Before Code
Displayed
Condition Check
FC**
10
Control checks to ensure evaporator is free of frost. Continuously veries
that T3a sensor (evaporator inlet temperature) is greater than 20F after 30
minutes of run time.
Probable refrigerant leak. Find and Repair.
Check T3a sensor mounting, wiring and resistance.
Check EEV wiring at control, coil placement, and operation.
Fd**
10
Control checks to ensure evaporator superheat
+
is OK (controlled by EEV).
Continuously veries the temperature difference between T3a sensor (evap
inlet temp) and T3b sensor (evap outlet temp) is greater than 5F after 30
mins of run time. Control also veries that T3a is greater than 10F less than
T5 ambient sensor.
Possible refrigerant leak. Check sealed system for leak.
Check that lter is clean. Check T3a, T3b and T5 sensor
mounting, wiring and resistance.
Check EEV wiring at control, coil placement, and operation.
FE**
10
Control checks to ensure the compressor discharge temperature never
exceeds 240F. Continuously veries that T4 sensor (compressor outlet
temperature) is less than 240F every minute of run time.
Possible refrigerant leak. Check sealed system for leak.
Check T4 sensor mounting, wiring and resistance.
Check EEV wiring at control, coil placement, and operation.
FF**
10
Control checks to ensure the Electronic Expansion Valve (EEV) is operating
properly and valve rotation is within range.
Probable refrigerant leak. Find and Repair.
Check EEV wiring at control, placement of EEV coil on
EEV valve body, and operation. Conrm audible pulse of
valve homing sequence at power restart.
Check T3a and T3b sensors mounting, wiring and
resistance.
FG 10
Control checks to ensure Ambient temperature is within an acceptable range
of 35ºF < [T5 ambient] <120ºF before starting the heat pump. If not, the unit
will switch to Electric (Only) Mode for that heating cycle only.
NO fault code is shown on the display.
No failure is assumed, but this information is provided for
completeness.
FI** 10
Control checks to ensure evaporator superheat
+
is <20ºF AND the EEV
position is <450 after 30 minutes of run time. If outside these limits, this
provides an early indication of a refrigerant leak. (Note: Target superheat is
generally 10ºF, and EEV generally operates at a position much lower than
450.)
Probable refrigerant leak. Find and Repair.
Check T3a, T3b, T5 sensor mounting, wiring and resistance.
Check EEV wiring at control, coil placement, and operation.
FJ 10
Control checks to ensure that the AC current draw is <= 20.5A while the
compressor and lower heating element are both enabled. If current draw is
>20.5A, the compressor will be disabled.
Check lower heating element rated wattage. Element
wattage is stamped on the heating element terminal block.
Correct wattage can be found on the water heater’s rating
plate.
FL 10
Control checks to ensure that T3a and T3b evaporator inlet and outlet
temperatures are within 2.5ºF of the T5 ambient temperature 20
minutes after defrost begins.
Check airow: fan operation, dirty lter, dirty evaporator.
Check T3a, T3b, T5 sensor mounting, wiring and resistance. Check EEV wiring at control, coil placement, and
operation.
F2
1
T2 tank temperature sensor failure Just before compressor starts, control
checks T2 sensor is within 30F - 170F temperature range.
Check T2 sensor mounting, wiring and resistance.
Use service mode to monitor T2 sensor temperature.
If T2 sensor checks OK, control assembly may have failed.
F3
10
Compressor failure. Control energizes compressor, but current sensor
detects no current ow.
Check compressor run capacitor.
Check compressor, overloads, relay and wiring.
Use service mode to manually cycle compressor on/off.
F4 10 Fan Failure Check fan, wiring, and control connection.
F5
10
T3a sensor (evap inlet temperature) failure. The control detects the thermistor output is at or nearly shorted or open circuit.
Check respective temperature sensor mounting, wiring to
control and resistance.
Use service mode to monitor sensor temperature.
If temperature sensor checks OK, control assembly may
have failed.
F6
10
T3b sensor (evap outlet temperature) failure. The control detects the thermistor output is at or nearly shorted or open circuit.
F7
10
T4 sensor (compressor outlet) failure. The control detects the thermistor
output is at or nearly shorted or open circuit.
F8
10
T5 sensor (ambient temperature) failure. The control detects the thermistor
output is at or nearly shorted or open circuit.
F9 10
Lower heating element failure. Control energizes lower element, but cur
-
rent sensor detects no current ow.
Check respective heating element and wiring connections
at element and control.
Use service mode to cycle element and check current
draw. Control assembly may have failed.
F10 10
Upper heating element failure. Control energizes Upper element, but cur-
rent sensor detects no current ow.
F11 1
Dry Tank fault. Control checks to ensure that the T2 tank temperature
sensor has not risen more than 5ºF during the rst 22 minutes after the unit
is powered on. (The compressor is engaged for 20 minutes after a 2 minute
wait for the system to allow the high and low side pressures to equalize.)
After 1 failed Dry Tank test, “F11” is displayed. After 5 failed tests, an audible
alarm will sound.
Check to ensure the tank is full of water. If full:
Check T2 sensor mounting, wiring and resistance.
Use service mode to monitor T2 sensor temperature.
If T2 checks OK, control assembly may have failed.
bAd linE
(F12)
1
The voltage is too low at power-up. The control monitors the input line voltage1 minute after power-up, and if the voltage is below 155V, the fault code
will be displayed.
Check electrical supply line connections. Voltage should
measure within +10/-15% of either 208 or 240 VAC,
depending upon power supply. Badline counts stored in
“F12” and can be monitored via the Control when placed in
diagnostics mode.Check heating elements are not shorted
to ground.
F13
1
Stuck Key fault. This indicates there is a button on the front panel that is
stuck down. This button is inoperable. Other buttons work normally. If the
button becomes free, the fault code will clear by itself.
Check to see if all buttons are operable.
Ensure control board is fully snapped into control housing.
If board is fully seated, control assembly has failed.
DirtyFilter**
(F14)
5
Filter LED is on, and audible alarm is sounding. Filter is too dirty to enable
proper function of unit. Number of “Dirty Filter” counts are stored in the
“F14” code and can be monitored via the Control when it is placed in Diagnostics Mode. The evaporator is operating at a colder
temperature than the ambient temperature as measured by T5.
Check to ensure Filter is clean. Filter cleaning instructions
are found in the owner’s manual.
Repeated dirty lter alarms that do not resolve by cleaning
are an indication of a sealed system leak. Find and repair
AND ash software to version 4.21 or later, or replace
control.
F15 10
DataFlash fault. The microcontroller has detected a problem in the DataFlash (permanent memory storage).
Control assembly may have failed.
F18 10
Current transformer miswired. F3, F9, and F10 fault codes have all
occurred during the same heating cycle.
Check that red L2 wire is through the CT201 current
transformer on the board. If it is, board needs to be
replaced
F19 10
Low line voltage during compressor operation. Sagging voltage occurs
over time, not at startup like a fault F12- bAd linE.
Check incoming line voltage is within +10/-15% of either
208 or 240 VAC, depending upon power supply.
Check heating elements are not shorted to ground.
F20 10
Condensate drain pan port blocked. Water heater will only operate in
Electric (Only) mode until the drain port is cleared and the sensor
is no longer in contact with water.
Check main drain on condensate drain pan. Unblock if
necessary. Check that the sensor is in the correct position
in the drain pan, on the screw post near the main drain
port. Ensure drain ttings do not reduce diameter at the
drain pan port and cause water to build up in pan.
F21 1
Application Update Failure. A problem occurred while updating the control
application.
Cycle power and try to complete the update again. If prob-
lems persist, reash software or replace the control board.
F22 1
Parametric Data Update Failure. A problem occurred while updating
parametric data.
Cycle power and try to complete the update again. If prob-
lems persist, reash software or replace the control board.
F23 10
Micro A/D Failure. The control has detected a microcontroller input port has
failed.
The control needs to be replaced.
* on some models ** Technicians use TB01-16
238-52395-00 02/18