The best way to repair a Coleman oil furnace is to first identify the actual problem and then repair or replace the damaged component. Common problems with Coleman oil furnaces include tripped circuit breakers, incorrectly set thermostats and defective oil pumps.
If a Coleman oil furnace does not start, first check to be sure that the unit is connected to a working electrical outlet. Replace any blown fuses, and reset tripped circuit breakers. Examine the motor on the burner assembly to see if it has burned out, and replace if necessary. If the problem persists, use a volt-ohmmeter to test the starting switch on the motor for continuity, and replace if faulty.
If the burner is running but there is no fire, check whether the burner nozzle, filter or oil line is clogged, and replace any of the failing parts. Confirm that the electrodes are set correctly and that the valve is open. If this does not fix the problem, examine the oil pump and the pump coupling. Replace a stripped pump coupling or a defective oil pump.
If a Coleman oil furnace is producing fumes or odors, adjust the burner, and replace the nozzle if clogged. Check whether the heat exchanger has cracked, and replace if necessary. If these repair methods do not fix the problem, contact a Coleman professional for assistance.