TROUBLESHOOTING
Standing Pilot Models
Main Burner Does Not Ignite
1.Check the electrical supply to the furnace.
2.Verify the furnace furnace
3.Check for proper thermostat operation.
4.Check for broken or open thermostat wires.
5.Verify the insulation located on the inside of the front panel is glued securely around the fan switch and the limit switch.
6.Shut off the electrical supply to the furnace and remove the electrical box cover.
7.Check for a defective transformer or blown fuse.
8.Check electrical circuit for proper grounding, polarity, and make sure the electrical connections are tight.
9.Check the limit switches. Did they fail to close?
10.Replace the electrical box cover and restore electrical power to the furnace. Turn the furnace
11.Check for 24 VAC at the gas valve. Replace the valve if the pilot is established and it does not open when powered with 24 volts.
Powered (24 VAC) Gas Valve - No Main Flame
1.Verify the manual
2.Check the pilot fl ame. It must be established.
3.Check the gas valve control lever. It must be in the ON position.
4.Check incoming gas pressure.
5.Replace the gas valve if the main burner does not come on under the above conditions.
Pilot Will Not Light or Goes Out
1.Check the incoming gas pressure.
2.Check for the proper pilot orifice. See specifi cations on the furnace nameplate.
3.Check for proper pilot fl ame adjustment. See Burner Adjustment section (page 22).
4.Verify the thermocouple millivoltage.If reading is not between 18 - 30 mv., the gas valve electromagnet may be defective. Replace the gas valve if necessary.
5.Verify the pilot shield is in place.
6.Check for gas leaks (page 18).
7.Check the fl ue assembly for air leaks.
8.See lighting procedures (pages 20 - 22).
Main Flame Is Not Burning Properly
1.Check the manifold gas pressure.
2.Check for the correct main burner orifi ce. See furnace nameplate for specifi cations.
3.Check the fl ue for any blockages or loose connections.
4.Check the combustion air passages for blockage.
High Gas Bills
a. Verify the proper orifi ces are being used.
b. Check the return air system. Is it clear and free of blockage?
c. Check the furnace fi lter. Is it clean or need replacing?
d. Verify the home is insulated, windows and doors fi t tightly, and there are no leaks in the heating duct system.
e. Check the room thermostat. Is the setting higher than necessary? Low humidity requires higher temperatures for the same level of comfort. Check for proper humidity level in the home.
Direct Ignition Furnaces Including Gas Gun M1B Series (see Table 9, page 29)
Burner Motor won’t Run -
1.Check the electrical supply to the furnace.
2.Verify the furnace furnace
3.Defective thermostat circuit - white and red thermostat low voltage leads (M1/M5M, M1/M5B models). If the burner motor or combustion fan runs, check:
•Thermostat connections
•Thermostat
4.No voltage to control module - determine if 24 volts (or 120 volts) is available to the control module. If voltage is not available check for:
•Blown fuse, defective transformer, circuit breaker, no electrical supply.
•Limit switch open.
•Loose connections.
Combustion Blower Runs - No Flame
1.Defective centrifugal switch (M1B Model).
•Check the operation of centrifugal switch by removing end bell of the burner motor.
•Clean contacts of motor.
•If the contacts are closed, replace the motor.
2.Defective pressure switch (M1M & M1G - 077, 090 Models) - check air tube and electrical connections.
3.Burner in purge mode - allow 75 seconds for
flame establishing period.
4.Check for proper electrical connections at purge timer, control box, or gas valve.
5.Check for gas supply - gas line valve on, control lever on.
Control Module is Powered - Ignitor won’t Heat Up
1.Disconnect ignitor leads at AMP receptacle and check for 120 volts at the plug during ignition sequence.
2.Replace ignition control if 120 volts is not available at AMP plug during ignition sequence.
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