Service manual

24
VI - TROUBLESHOOTING (cont.)
ERROR MESSAGES
Error Faulty Remedy
32 Outgoing Water Check sensor wiring for damage.
Temperature Sensor Faulty Check resistance on sensor.
Check and clean scale from sensor.
Replace sensor.
33 Heat Exchanger Outgoing Check sensor wiring for damage.
Temperature Sensor Faulty Check resistance on sensor.
Check and clean scale from sensor.
Replace sensor.
34 Combustion Air Check sensor wiring for damage.
Temperature Sensor Faulty Check resistance on sensor.
Check and clean dirt from sensor.
Ensure fan blade is tight on motor shaft and it is in good
condition. Clean blower blades if dirty.
Check for restrictions in air flow around unit and vent terminal.
Replace sensor.
52
Modulating Solenoid Valve Check modulating gas solenoid valve wiring harness for loose
Signal Abnormal or damage terminals.
Check resistance on solenoid valve.
61 Combustion Fan Failure Ensure fan motor will turn freely. Motor will operate with a
small amount of r
estriction.
Chec
k wiring harness t
o mot
or for damaged and/or loose
connections.
Check resistance on motor winding.
71 SV0, SV1, SV2, and SV3 Check wiring harness to all solenoids for damage and/or loose
Solenoid Valve Circuit Faulty connections.
Chec
k resistance on each solenoid.
72 Flame Sensing Device Faulty Check micro amps produced by flame rod.
Remove f
lame rod and check for carbon build-up, clean with
sand paper.
Ensure flame rod is touching flame when unit fires.
Check inside burner chamber for any foreign material blocking
flame at f
lame r
od.
Chec
k all wiring t
o f
lame rod f
or damag
e.
Replace f
lame rod.
LC Scale Build-up in Heat Exchanger Turn off power supply, then reapply power; if code does not
reappear separate control wires from the unit's power supply.
Flush heat exchanger.
Replace heat exchanger.
No Nothing happens when water flow Clean inlet water supply filter.
Code is activated Ensure you have at least the minimum flow rate required to fire
unit.
Chec
k f
or pipe dope inside w
ater flow control turbine.
On new installations ensure hot and cold water lines are not
crossed.
Check for bleed over. Isolate unit from building by turning off
hot w
at
er line t
o building, t
hen open y
our pressure relief valve.
If unit f
ires, there's a bleed over in your plumbing.
If a circulating system is in use, it must be isolated also.
Remote control does not light up but you have 12 VDC at the
terminals for controls.
Disconnect water flow control motor, then turn on hot water, if
unit fires replace water flow control assembly.
Chec
k resistance on water flow control sensor.