User Manual
LAARS Heating Systems
Page 36
CODE# PROBLEM PROBABLE CAUSE SOLUTION
COMMON LOCKOUT CODES
27 Internal error Flame rod to ground Check wiring / probe grounded, dirty probe
47 Flame rod to ground leakage Faulty ame detector Clean or replace ame detector
49 24VAC voltage low/high Faulty transformer Check/correct supply line voltage; replace faulty
transformer
52 Motor tachometer fault Faulty fan / fan wiring Check fan harness wiring for continuity; replace faulty
fan circuit
53 AC inputs phase reversed Reverse 24V hot/neutral - use common ground
61 Anti short cycle Call for heat will be held Change ASC timer setting
until timer resets
62 Fan speed not proved Dirty / defective fan Clean or replace fan; check wiring
63 LCI off Safety chain interrupt Check ow switch, aux high limit, LWCO, gas
pressure switches, condensate level and correct
problem
69 Outlet high limit High limit tripped Determine cause: low/no ow, valves closed, settings
and correct
79 Outlet high limit
80 DHW high limit High limit reached Check pump, time delay, valves closed, etc. and
81 Delta T inlet/outlet limit correct overtemp
82 Stack limit High limit reached Could be caused by high ambient temperature, or
high return water temperature
88 Outlet T-rise limit
90 Heat exchanger high limit High limit reached Diagnose / repair cause of high temperature
91 Inlet sensor fault
92 Outlet sensor fault
93 DHW sensor fault Faulty sensor or wiring Check wiring / replace sensor; condition can be
95 Stack sensor fault caused by short
96 OAT temperature sensor fault Faulty outdoor air Check wiring and sensor for short; replace sensor
temperature sensor is open or shorted
105 Flame detected Flame exists at burner Clean burner of soot or other debris that could
out of sequence when it should not be maintain ame
106 Flame lost in MFEP Unstable ame during
107 Flame lost early in Run lighting / ame proving Check venting, gas supply pressure, burner, fan, etc.
108 Flame lost in Run sequence
109 Ignition failed Problem with ignitor, or Check / replace ignitor, wiring; check for shorting
other ignition-related device in ignitor cable
113 Flame circuit timeout Flame not established Check all combustion components; purge gas;
within expected time limit check ignition source
122 Lightoff rate proving failed
123 Purge rate proving failed
128 Fan speed failed / prepurge Fan did not reach Check fan wiring; replace fan
129 Fan speed failed / preignition expected RPM
130 Fan speed failed / ignition
131 Fan movement detected Fan should not be moving Check for common venting problems or otherwise
during standby when not powered forced air
132 Fan speed failed during run Fan lost or gained speed Fan overheating or otherwise failing; check cable;
during run sequence away replace fan
from control spec
137 ILK failed to close No power at interlock ILK Check J5 pin 1 for power - if no power, conrm
safeties are closed
49 Maximum cycle count Control operates correctly,
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