SERVICING
34
Complaint 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 Satasfied
Short Cycles
Long Cycles
Soot and /or Fumes
To 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-3
No Low Voltage
•
Check Transformer S-4
Faulty Thermostat
••••
Check Thermostat S-3
Faulty Transformer
•
Check Transformer S-4
Poor or High Resistance Ground
•
Measure Ground Resistance S-313
Improper Heat Anticipator Setting
•• ••
Adjust Heat Anticipator Setting S-3
Improper Thermostat Location
•• ••
Relocate Thermostat
Faulty Limit or Roll Out Switch
••
Test Control S-300-302
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-304
Faulty Induced Draft Blower
••
Test Blower S-309
Broken or Shorted Ignitor
•
Test Ignitor S-312
Faulty Combustion Relay
••
Test Relay S-20
Dirty Flame Sensor, Low uA
•
Clean Flame Sensor S-314
Flame Sensor not in Flame, Low uA
•
Test/Adjust Position of Flame Sensor S-314
Faulty Gas Valve
•••
Replace Gas Valve S-304
Open Auxillary Limit
••
Reset Control S-301
Improper Air Flow or Distribution
••
Check Duct Static
Cycling on Limit
•• •
Check Controls & Temperature Rise S-300
Delayed Ignition
•
Test for Delayed Ignition S-308
Flashback
•
Test for Flashback S-309
Orifice Size
•••
Check Orifices S-306
Gas Pressure
• •••
Check Gas Pressure S-307
Cracked Heat Exchanger
•
Check Burner Flames S-302
Stuck Gas Valve
•••
Replace Gas Valve S-304
Furnace Undersized
•
Replace with Proper Size Furnce
Faulty Pressure Switch
•••
Test Pressure Switch S-310
Blocked or Restricted Flue
•
Check Flue/Drawdown Pressure S-310
Open Roll Out Switch
••
Test Control S-302
Collector Box "J" Tube Position
••
Test Negative Pressure S-310
Bouncing On Pressure Switch
•
Test Negative Pressure S-310
GAS HEATING - SERVICE ANALYSIS GUIDE
S-1, S-4
S-16
S-315
S-7
S-200
Replace with proper size furnace
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