Laars NTH, Installation And Operation Instructions Manual, Page: 74 / 96

Page 70
LAARS Heating Systems
50 Modulation fault H Internal sub-system fault.
1. Review alert messages for possible trends.
2. Correct possible problems.
51 Pump fault H Internal sub-system fault.
1. Review alert messages for possible trends.
2. Correct possible problems.
52 Motor tachometer fault H Internal sub-system fault.
1. Review alert messages for possible trends.
2. Correct possible problems.
53 AC input phases reversed L 1. Check the module and display connections.
2. Check the module power supply and make
sure that both frequency and voltage meet the
specifi cations.
3. On 24 VAC applications, assure that J4 terminal
10 and J8 terminal 2 are connected together.
59
Internal Fault: Mux pin shorted L Internal Fault.
1. Reset module.
2. If fault repeats, replace module.
61 Anti short cycle H Will not be a lockout fault. Hold Only.
62 Fan speed not proved H Will not be a lockout fault. Hold Only.
63
LCI (Limit Control Input) OFF
H 1. Check wiring and correct any faults.
2. Check Interlocks connected to the LCI to assure
proper function.
3. Reset and sequence the module; monitor the LCI
status.
4. If code persists, replace the module
64
PII (Pre-Ignition Interlock) OFF
H or L 1. Check wiring and correct any faults.
2. Check Preignition Interlock switches to assure
proper functioning.
3. Check the valve operation.
4. Reset and sequence the module; monitor the PII
status.
5. If code persists, replace the module.
67
ILK (Interlock) OFF
H or L 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.
68
ILK (Interlock) ON
H or L
70 Wait for leakage test completion H 1. Internal Fault. Reset module.
2. If fault repeats, replace module.
78 Demand Lost in Run H 1. Check wiring and correct any possible errors.
2. If previous steps are correct and fault persists,
replace the module.
Code Description Lockout
or Hold
Procedure