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Fault
Fault Counts
Condition
Code
Before Code
Displayed
Displayed
Control checks to ensure evaporator is free of frost. Continuously verifies
10
that T3a sensor (evaporator inlet temperature) is greater than 20F after
FC
30 minutes of run time.
Control checks to ensure evaporator superheat* is OK (controlled by EEV).
Continuously verifies the temperature difference between T3a sensor
10
(evap inlet temp) and T3b sensor (evap outlet temp) is greater than 5F
after 30 mins of run time. Control also verifies that T3a is greater than
Fd
10F less than T5 ambient sensor.
Control checks to ensure the compressor discharge temperature never
10
exceeds 240F. Continuously verifies that T4 sensor (compressor outlet
FE
temperature) is less than 240F every minute of run time.
Control checks to ensure the EEV is operating properly and valve rotation
10
is within range.
FF
Control checks to ensure Ambient temperature is within an acceptable
range before starting heat pump. Heat pump operating range is
FG
10
35ºF < [T5 ambient] <120ºF. If ambient temperature (as viewed by T5
sensor) is outside of this range, the unit will switch to Electric/Standard
Mode for that heating cycle only. NO fault code is shown on the display.
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
FI*
10
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.)
Control checks to ensure that the AC current draw is <= 20.5A while the
FJ
10
compressor and lower heating element are both enabled. If current draw
is >20.5A, the compressor will be disabled.
Control checks to ensure that T3a and T3b evaporator inlet and outlet
FL
10
temperatures are within 2.5ºF of the T5 ambient temperature 20
minutes after defrost begins.
T2 tank temperature sensor failure Just before compressor starts, control
1
checks T2 sensor is within 30F - 170F temperature range.
F2
Compressor failure. Control energizes compressor, but current sensor
10
detects no current flow.
F3
F4
10
Fan failure
T3a sensor (evap inlet temperature) failure. The control detects the
10
thermistor output is at or nearly shorted or open circuit.
F5
T3b sensor (evap outlet temperature) failure. The control detects the
10
thermistor output is at or nearly shorted or open circuit.
F6
T4 sensor (compressor outlet) failure. The control detects the thermistor
10
output is at or nearly shorted or open circuit.
F7
T5 sensor (ambient temperature) failure. The control detects the thermis-
10
tor output is at or nearly shorted or open circuit.
F8
Lower heating element failure. Control energizes lower element, but
F9
10
current sensor detects no current flow.
Upper heating element failure. Control energizes Upper element, but
F10
10
current sensor detects no current flow.
Dry Tank fault. This test is run within the first 22 minutes after the unit
has powered on. (The compressor is engaged for 20 minutes after a
2minute wait for the system to allow the high and low side pressures to
F11
1
equalize.) The tank temperature, T2, is read and verified it has not risen
more than 5 deg F. If it has, this indicates there is not enough water in
the tank for water heater operation. After 1 failed Dry Tank test, "F11" is
displayed. After 5 failed tests, an audible alarm will sound.
The voltage is too low at power-up. The control monitors the input line
bAd linE
voltage1 minute after power-up, and if the voltage is below 155V, the
1
fault code will be displayed.
(F12)
Stuck Key fault. This indicates there is a button on the front panel that is
1
stuck down. This button is inoperable. Other buttons work normally. If
F13
the button becomes free, the fault code will clear by itself.
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
DirtyFilter
5
"F14" code and can be monitored via the Control when it is placed in
(F14)
Diagnostics Mode. The evaporator is operating at a colder
temperature than the ambient temperature as measured by T5.
DataFlash fault. The microcontroller has detected a problem in the
F15
10
DataFlash (permanent memory storage).
Current transformer miswired. F3, F9, and F10 fault codes have all
F18
10
occurred during the same heating cycle.
F19
10
Low Line Voltage.
Condensate drain pan port blocked. Water heater will only operate in
F20
10
standard/electric mode until the drain port is cleared and the sensor
is no longer in contact with
Application Update Failure. A problem occurred while updating the
F21
1
control application.
Parametric Data Update Failure. A problem occurred while updating
F22
1
parametric data.
Micro A/D Failure. The control has detected a microcontroller input port
F23
10
has failed.
* on some models
water.
Check
Check T3a sensor mounting, wiring and resistance.
Check Electronic Expansion Valve (EEV) operation.
Check sealed system for refrigerant leak.
Check that filter is clean. Check T3a, T3b and T5 sensor mount-
ing, wiring and resistance.
Check Electronic Expansion Valve (EEV) operation.
Check sealed system for refrigerant leak.
Check T4 sensor mounting, wiring and resistance.
Check Electronic Expansion Valve (EEV) operation.
Check sealed system for refrigerant leak.
Check Electronic Expansion Valve (EEV) operation.
Check T3a and T3b sensors mounting, wiring and resistance.
Check sealed system for refrigerant leak.
No failure is assumed, but this information is provided for
completeness.
Check sealed system for refrigerant leak.
Check T3a, T3b, T5 sensor mounting, wiring and resistance.
Check Electronic Expansion Valve (EEV) operation.
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.
Check T3a, T3b, T5 sensor mounting, wiring and resistance.
Check Electronic Expansion Valve (EEV) operation.
Check T2 sensor mounting, wiring and resistance.
Use service mode to monitor T2 sensor temperature.
Control assembly may have failed.
Check compressor run capacitor.
Check compressor, overloads, relay and wiring.
Use service mode to manually cycle compressor on/off.
Check fan and wiring.
Check T3a sensor mounting, wiring and resistance.
Use service mode to monitor T3a sensor temperature.
Control assembly may have failed.
Check T3b sensor mounting, wiring and resistance.
Use service mode to monitor T3b sensor temperature.
Control assembly may have failed.
Check T4 sensor mounting, wiring and resistance.
Use service mode to monitor T4 sensor temperature.
Control assembly may have failed.
Check T5 sensor mounting, wiring and resistance.
Use service mode to monitor T5 sensor temperature.
Control assembly may have failed.
Check lower heating element and wiring.
Use service mode to cycle element and check current draw.
Control assembly may have failed.
Check Upper heating element and wiring.
Use service mode to cycle element and check current draw.
Control assembly may have failed.
Check to ensure the tank is full of water.
Check T2 sensor mounting, wiring and resistance.
Use service mode to monitor T2 sensor temperature.
Control assembly may have failed.
Check electrical supply line connections. Voltage should
measure either 208 VAC 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 to see if all buttons are operable.
Control assembly has failed
Check to ensure Filter is clean. Filter cleaning instructions are
found in the owner's manual.
Repeated dirty filter alarms that do not resolve by cleaning the
filter may be an indication of a fan failure.
Control assembly may have failed.
Check that red L2 wire is through the CT201 current
transformer on the board. If it is, board needs to be replaced
Check incoming line
voltage.
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.
Cycle power and try to complete the update again. If prob-
lems persist, replace the control board.
Cycle power and try to complete the update again. If prob-
lems persist, replace the control board.
The control needs to be replaced.
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