DIY Furnace Troubleshooting & Repairs
Furnace malfunctions are fairly common in both residential and commercial buildings. In many cases, you’ll need help from a repair professional to correct the problems affecting your building. However, before you call a professional service provider, you can take a variety of do-it-yourself steps to help you troubleshoot the situation.
If you’re lucky, the problem you find may also have a DIY solution that allows you to avoid calling for any help at all. Find out what you can do when your furnace is not working.
Troubleshooting & Repairs for Gas-Powered Furnaces
Furnaces typically fall into one of two categories: units powered by natural gas or propane, and units powered by electricity. (A small percentage of older buildings may also have oil-powered furnaces.)
While DIY troubleshooting and repair steps are largely the same for all furnaces, you should still take the technology used in your unit into consideration. We’ll start with natural gas- and propane-powered furnaces.
Begin by Checking the Thermostat
You’d be surprised to learn how often heating problems in homes and commercial buildings trace back to a thermostat set incorrectly or not activated at all. Before you do anything else, check for these issues. Set the proper temperature (or temporarily turn the heat up above this temperature) and make sure you place the furnace fan in the “on” position.
If the Fan Won’t Turn On
If the furnace fan won’t turn on, check for blown fuses or tripped breakers on your building’s electrical panel. When you follow proper safety precautions, do-it-yourself correction of these problems is typically quite straightforward (i.e., replacing the fuse or resetting the breaker).
If you don’t notice any issues at the electrical panel, go to your furnace and take a look through the inspection window installed on the blower compartment. Normally, this view will reveal a green light flashing on and off. If you don’t see this light, you may have exhausted your DIY options. That’s because the list of potential reasons for the malfunction now includes:
- A faulty thermostat
- A faulty blower motor, and
- Problems with other components such as the furnace control board, transformer or run capacitor
Check the Pilot Light and Burners
Lack of heat production in a gas- or propane-powered furnace may be caused by problems with the pilot or the main burner ignited by the pilot. Most furnaces installed in the 21st century rely on an electronic spark ignition to control these components. Older units may instead rely on a constantly lit pilot light. If your furnace has a spark ignition system, check for a telltale rapid clicking sound coming from the pilot or the main burner. If you hear this noise but don’t see even intermittent flames, possible causes of your problems include a damaged furnace control board and a blocked flue.
If you hear this noise but do see intermittent flames, you face potential issues that include a clogged flame sensor or clogged pilot assembly. If your furnace has a constant pilot light, make sure this small flame is present. If you have a functional pilot but no main burner activity, carefully check the temperature on the side of the furnace.
A cool surface here could point toward one of several issues, including a damaged thermostat, a damaged gas valve and problems with the furnace limit control or control board. Advanced do-it-yourselfers may feel comfortable exploring these potential causes further, but if you have any doubts about your abilities, call a professional instead.
Check the Blower
If you don’t have any pilot or main burner malfunctions, it’s time to check the furnace blower. Normally, a blower will turn on just a few minutes after you activate the system. If this doesn’t happen, you may have a damaged blower motor or a run capacitor.
Troubleshooting & Repairs for Electric Furnaces
If you have an electricity-powered furnace installed in your home or business, the initial troubleshooting stages are the same as those you would take for problems with a gas- or propane-powered unit. Start by checking the thermostat and looking for problems at the electrical panel. If you don’t notice any issues, you’ll have to take further steps that are unique to electric furnaces.
Check for Wiring Issues
In some cases, power surges and other problems can damage the wiring on an electricity-powered furnace. Look for telltale indications such as melted or scorched wires and damaged electrical connections. Depending on your DIY skill level, you may choose to correct these problems yourself or turn to an experienced professional.
Check the Fan
If the fan won’t turn on you and don’t have any breaker, fuse or wiring issues, you may be dealing with damage in any one of several furnace components, including the thermostat, the fan relay, the control transformer, the furnace control board and the blower motor. If the fan will start, but your unit still won’t produce heat, you’re likely facing one of these problems:
- A damaged heating element
- A malfunctioning heat sequencer
- A malfunctioning control board
- A damaged limit control, or
- Previously undetected wiring issues (e.g., a loose connection or burn damage)
Your Fan Works, But You Still Don’t Have Adequate Heat
All electric furnaces are rated to increase indoor air by a certain amount. If you feel you don’t have adequate heat production, you can check your furnace’s ability to meet this standard by measuring the temperature at two locations: the vent closest to the unit and the return duct closest to the unit. Note the difference between the two temperatures and compare this number to the rating listed on the furnace.
If the unit isn’t producing enough heat, it may have at least one faulty heating element. (You can also use this same technique to check for excessive heat production, a problem often caused by a malfunctioning or improperly set blower motor.) Whether dealing with a gas-powered or electric furnace, always make sure to stay within the bounds of your ability when considering a DIY solution.
If you’re not sure about the steps required to safely troubleshoot or repair any kind of furnace, you can call on the experts at West Coast Chief Repair. Our deep experience in this field allows us to accurately diagnose even the most obscure issues. In most cases, any increases in your costs are more than compensated for by your long-term peace of mind.