A.O. Smith 3400 - Manual (Page 63)

63
CODE DESCRIPTION RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
122 Lightoff rate proving failed 1. Check wiring and correct any potential wiring
errors.
2. Check VFDs ability to change speeds.
3. Change the VFD
4. If the fault persists, replace the module.
L
123 Purge rate proving failed L
124 High fire switch OFF 1. Check wiring and correct any potential wiring
errors.
2. Check High Fire Switch to assure proper function
(not welded or jumpered).
3. Manually drive the motor to the High Fire position
and adjust the HF switch while in this position
and verify voltage through the switch to the HFS
input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
125 High fire switch stuck ON H
126 Low fire switch OFF 1. Check wiring and correct any potential wiring
errors.
2. Check Low Fire Switch to assure proper function
(not welded or jumpered).
3. Manually drive the motor to the High Fire position
and adjust the LF switch while in this position and
verify voltage through the switch to the LFS input
with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
127 Low fire switch stuck ON H or L
128 Fan speed failed during prepurge 1. Check wiring and correct any potential wiring
errors.
2. Check VFDs ability to change speeds.
3. Change the VFD
4. If the fault persists, replace the module.
H or L
129 Fan speed failed during preignition H or L
130 Fan speed failed during ignition H or L
131 Fan movement detected during standby H
132 Fan speed failed during run H
133-135 RESERVED
Start Check Faults
136 Interrupted Airflow Switch failed to close 1. Check wiring and correct any possible wiring
errors.
2. Check Interrupted Airflow switch(es) to assure
proper function.
3. Verify voltage through the airflow switch to the
IAS input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
137 ILK failed to close 1. Check wiring and correct any possible shorts.
2. Check Interlock (ILK) switches to assure proper
function.
3. Verify voltage through the interlock string to the
interlock input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
138-142 RESERVED
FAULT CODES 149 THROUGH 165 ARE
OEM SPECIFIC FAULT CODES.
143 Internal fault: Flame bias out of range 1 Contact the qualified service technician. L
144 Internal fault: Flame bias out of range 2 Contact the qualified service technician. L
145 Internal fault: Flame bias out of range 3 Contact the qualified service technician. L
146 Internal fault: Flame bias out of range 4 Contact the qualified service technician. L
147 Internal fault: Flame bias out of range 5 Contact the qualified service technician. L
148 Internal fault: Flame bias out of range 6 Contact the qualified service technician. L