LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual - Manual (Page 107)

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Service Manual - NeoTherm 500
Appendix 1 - Error Codes (continued)
Code Description L or H Procedure
153 Combustion pressure off H or L 1. Check wiring and correct any errors.
2. Inspect the combustion pressure switch to make sure
it is working correctly.
3. Reset and sequence the relay module.
4. During standyby and prepurge, measure the volt-
age between J6 terminal 5 and L2 (N). Supply voltage
should be present. If not, the lockout switch is defective
and needs replacing.
5. If the fault persists, replace the relay module.
154 Purge fan switch on H or L 1. Purge fan switch is on when it should be off.
2. Check wiring and correct any errors.
3. Inspect the purge fan switch J6 terminal 3 and its
connections. Make sure the switch is working correctly
and is not jumpered or welded.
4. Reset and sequence the relay module.
5. If the fault persists, replace the relay module.
155 Purge fan switch off H or L 1. Purge fan switch is off when it should be on.
2. Check wiring and correct any errors.
3. Inspect the purge fan switch J6 terminal 3 and its
connections. Make sure the switch is working correctly
and is not jumpered or welded.
4. Reset and sequence the relay module.
5. If the fault persists, replace the relay module.
156 Combustion pressure and flame on H or L 1. Check that flame is not present in the combustion
chamber. Correct any errors.
2. Make sure that the flame detector is wired to the cor-
rect terminal.
3. Make sure the flame and ground wires are protected
from stray noise pickup.
4. Reset and sequence the module, if code reappears,
replace the flame detector.
5. Reset and sequence the module, if code reappears,
replace the module.
157 Combustion pressure and flame off L 1. Check that flame is not present in the combustion
chamber. Correct any errors.
2. Make sure that the flame detector is wired to the cor-
rect terminal.
3. Make sure the flame and ground wires are protected
from stray noise pickup.
4. Reset and sequence the module, if code reappears,
replace the flame detector.
5. Reset and sequence the module, if code reappears,
replace the module.
158 Main valve on L 1. Check the main valve terminal wiring and correct any
errors.
2. Reset and sequence the module. If fault persists,
replace the module.
App1
cont.