How Do I Fix Furnace Problems?

Fixing your furnace includes becoming knowledgeable about how a thermostat operates.

Warm air through a furnace system can be delivered via oil, gas or electricity. Each of these comes with its own set of problems. Troubleshooting almost all furnaces begins with the same process that can ultimately lead to either a very simple fix or one that requires the assistance of a professional. The thermostat in particular can be a source of relatively simple problems.

Things You'll Need

• Replacement fuse
• Screwdriver
• Can of compressed air
• Slip of paper
• Needle-nose pliers
• Bubble level
• Calibration wrench

Instructions

1. Check the main service panel for either a blown fuse or a tripped circuit breaker, depending on the system your house uses. A furnace that won't start up at all can often be fixed simply by replacing the fuse or resetting the breaker.

2. Make sure that the thermostat has not been reset at a temperature that causes the furnace to kick on or off outside of its usual pattern. The thermostat may have been reset by another family member.

3. Remove the cover to the thermostat if the problem is not a fuse or circuit breaker and the thermostat setting has not been tampered with. Either snap off the cover directly or remove a small retaining screw on the bottom. Use a can of compressed air to remove dust and dirt particles inside the thermostat housing.

4. Locate the exposed contact points inside the thermostat housing. Use a business card, dollar bill or slip of paper to clean the contact points by drawing the paper between the points.

5. Remove the mounting screws in the front assembly of the thermostat and remove it from the wall plate. Inspect the device for signs of loose wire connections. Use a pair of needle-nose pliers to tighten loose wire terminals.

6. Place a small bubble level across the top of the wall plate while you have it exposed to search for loose wiring. Make sure that the thermostat is perfectly level -- a thermostat that is not level will not perform as efficiently. Check the thermostat any time you are aware that it has been bumped or something else has happened that may have thrown it out of alignment.

7. Find the nut located behind the bimetal coil inside some models of thermostats. Use a calibration wrench to turn the nut either slightly to the right or left for proper recalibration that will fix the problem of a furnace kicking on at a temperature other than the one you've set. Turn the shaft found at the center of the coil with a screwdriver on thermostat models that don't use the nut for calibration. Make sure to hold the dial shaft with one hand to keep it from moving while turning the shaft with the other hand.

8. Go to the wall plate if the furnace fails to kick on. Look for a small jumper wire situated between the power terminals. These wires are usually red and white, so look for the wire located between them. Touch the jumper wire and wait to see if the furnace starts. If the furnace does start after this procedure, the thermostat is faulty and should be replaced.

Tips & Warnings

• Turn off the power to the furnace when troubleshooting or repairing the furnace. The exception to this is when you are testing the thermostat to see if it is working.

References

• Hometips.com: Fixing a Furnace
• "Time-Life Fix-it-Yourself Home Heating and Cooling;" Kenneth Winchester, Ed.; 1988
• "The Stanley Complete Step-by-Step Book of Home Repair and Improvement;" William L. Broecker, Ed.; 1993