Series
THE
Page
27 LT194
Feb
2017
TROUBLESHOOTING
Burner Blower / Motor Fails To Run
Is the thermostat calling for heat? Is there 115V at the burner receptacle?
Check blower for obstructions. Replace blower if necessary.
Pressure Switch (N.O.) Failed Closed. Replace as necessary.
Check High Limit Switch (N.C.) for continuity.
Heat Exchanger Blower / Motor Fails To Run
Check heat exchanger blower power cord is connected to burner box cable connector.
Check blower for obstructions. Replace blower if necessary.
The Ignition Module Fails to Energize the Igniter
Check air pressure switch performance with a manometer – Compare with switch setting.
Ensure the correct size of exhaust and air intake pipes were used per the instruction manual for vent
length. Ensure maximum number of elbows or equivalent feet of both pipes was not exceeded. Ensure
there are no obstructions in the exhaust and air intake pipes.
If the air pressure switch performance test results prove the air pressure switch is working properly, and all
other steps are followed, and fault code persist – replace the control.
No Gas Supply
Check to see if manual supply valve to heater is ON (Open). No manifold pressure indicates valve is
closed. Gas pressure downstream of gas control can be measured by connecting a manometer to
pressure tap on control.
Supply gas pressure can be checked at 1/8" NPT pressure tap in gas supply system.
Burner Does Not Light
Is spark visible through site glass during ignition trial? If no, further electrical checks by a qualified service
person are required.
Check to see if gas lines were properly purged of air.
Check inlet and manifold gas pressure during ignition period.
Check for proper orifice and air plate.
Burner Does Not Stay Lit
Check ground wire continuity.
Check insulation on the igniter leads.
Measure flame signal current; it should be between 2 to 6 micro amps dc. Minimum 0.8 micro amps.
Clean flame rod if necessary.
Replace module if necessary.