Older Coleman gas furnaces feature a continuously burning pilot light that must be lit for the unit to operate. Utility providers and the gas heating industry recommend yearly inspections of such furnaces to ensure safety and efficiency, and many utilities offer free or low-cost furnace inspection and pilot-lighting services. Do-it-yourselfers attempting to light the pilot fixture should thoroughly read and follow directions in the owner's manual (when available), plus exercise caution while working on the appliance.
Make certain the area around the furnace is clean and free of clutter, especially flammable materials such as paint or household cleaners. Visually inspect the unit for cracks, rust or other signs that the unit needs repair or replacement. If any defects are spotted, contact a professional HVAC technician or your utility provider.
Locate the owner's manual, often found in a plastic sleeve taped to outside of the furnace. It should contain specific instructions for igniting the pilot light on your Coleman furnace. If the manual is not available, find the plate on the unit that contains the model and serial number and search for instructions online. Directions for lighting the pilot also may be written on the furnace itself.
Locate the control knob on the gas line next to the furnace. Turn the knob to the "off" position and allow a couple of minutes for accumulated gas to escape.
Turn the knob to the "pilot" position and check for a gas smell, which could indicate a potentially dangerous leak. If you smell gas, turn the knob to the "off" position and contact your utility provider or an HVAC technician.
If no gas smell is present, search for the pilot fixture, a small tube inside the furnace that extends from the gas line and can be accessed through a hole in the side of the furnace. Press down on the knob (which should still be in the "pilot" position), light the match and place the flame near the pilot fixture.
If the pilot lights, continue holding the knob for one minute then release. If the pilot fixture does not light or goes out when you release the knob, repeat this step.
If the pilot fixture will not light or does not stay lit after several attempts, contact an HVAC professional. The unit likely needs repair or replacement.