Service Manual

SERVICING
51
Service Problem No Heat Unsatisfactory Heat
POSSIBLE CAUSE
DOTS IN ANALYSIS
GUIDE INDICATE
"POSSI BL E CAUSE"
SYMPTOM
System Will Not Start
Burner Won't Ignite
Burner Ignites-Locks Out
Burner Shuts Off prior to T'Stat being Satisfied
Short Cycles
Long Cycles
Soot and /or Fumes
Too Much Heat
Not Enough Heat
Test Method
Remedy
See Service Procedure Reference
Power Failure
•
Test Voltage
S-1
Blown Fu se
•
Test Voltage
S-4
Loo se Co nnection
•
Check Wiring
S-2
Shorted or Broken Wires
•
Check Wiring
S- 3A
No L ow Vo lta ge
•
Check Transfor mer
S-4
Faulty Th ermostat
•••••
Check Thermostat
S- 3A
Fa ulty Transformer
•
Check Transfor mer
S-4
Poor or High Resistance Ground
•
Measure Ground Resistance
S-17B
Improper Heat Anticipator Setting
•• • •
Adjust Heat Anticipator Setting
S-3B
Improper Thermostat Location
•• • •
Relocate Thermostat
S- 316
Faulty Limit or Roll Out Switch
••
Test Control
S-300 / S-302
Fa ulty Fla me Sensor
•
Test Flame Sensor
S- 314
Faulty Ignition Control
•••
Test Control
S- 313
Gas Va lve or Gas Supp ly Shut Off
•
Turn Valves to On Position
S- 317
Faulty Induced Draft Blower
••
Test Induced Draft Motor
S- 303
Fa ulty Blower Motor (PSC)
••
Test B lower Motor (PSC)
S-16A,B,C
Broken or Shorted Ignitor
•
Test Ignitor
S- 308
Dirty Flame Sensor, Low UA
•
Clean Flame Sensor
S- 314
Stuck Gas Valve
•••
Replace Ga s Valve
S- 304
Fa ult y G as Val ve
•••
Replace Ga s Valve
S- 304
Ope n Auxil iary Limit
••
Reset Control
S- 301
Improper Air Flow or Distribution
••
Check Duct Static
S- 200
Cycling on Li mit
•• •
Check Controls & Temperature Rise
S-201 / S-300
Delayed Ignition
•
Test for Delayed Ignition
S- 312
Fl ashback
•
Test for Flashback
S-309 / S-311
Orifice Si ze
•• •
Check Orifices
S-306 / S-311
Gas Pressu re
••••
Check Gas Pressure
S- 307
Cr acked Heat Exchanger
•
Check Burner Flames
S- 305
Furnace Undersized
••
Replace with Proper Size Furnace
S- 318
Furnace Oversized
•
Replace with Proper Size Furnace
S- 318
Faulty Pressure Switch
•••
Test Pressure Switch
S- 310
Blocked or Restricted Flue
•
Check Flue/Drawdown Pressure
S- 310
Ope n Roll Ou t Swi tch
••
Test Flame Roll Out Control
S- 302
Bouncing On Pressure Switch
•
Test Ne gative Pr essure
S- 310