GMES8 GCES8 Service Manual

42
SERVICING
Service Problem
No Heat Unsatisfactory Heat
POSSIBLE CAUSE
DOTS IN ANALYSIS
GUIDE INDICATE
"POSSIBLE 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 Fuse
•
Test Voltage
S-4
Loose Connection
•
Check Wiring
S-2
Shorted or Broken Wires
•
Check Wiring S-3A
No Low Voltage
•
Check Transformer S-4
Faulty Thermostat
• • • • •
Check Thermostat S-3A
Faulty Transformer
•
Check Transformer 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
Faulty Flame Sensor
•
Test Flame Sensor S-314
Faulty Ignition Control
•
• •
Test Control S-313
Gas Valve or Gas Supply Shut Off
•
Turn Valves to On Position
S-317
Faulty Induced Draft Blower
• •
Test Induced Draft Motor S-303
Faulty Blower Motor (PSC & ECM)
•
•
Test Blower Motor (PSC & ECM)
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 Gas Valve S-304
Faulty Gas Valve
• • •
Replace Gas Valve
S-304
Open Auxiliary Limit
• •
Reset Control S-301
Improper Air Flow or Distribution
• •
Check Duct Static S-200
Cycling on Limit
• •
•
Check Controls & Temperature Rise
S-201 / S-300
Delayed Ignition
•
Test for Delayed Ignition S-312
Flashback
•
Test for Flashback S-309 / S-311
Orifice Size
• • •
Check Orifices
S-306 / S-311
Gas Pressure
• • • •
Check Gas Pressure S-307
Cracked 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
Open Roll Out Switch
•
•
Test Flame Roll Out Control
S-302
Bouncing On Pressure Switch
•
Test Negative Pressure S-310