It is not unusual for a gas furnace to make a clicking noise when it first starts up. However, if you continue to hear a clicking noise beyond the startup cycle, you will need to address the underlying cause. As recommended within this AC repair article catalog, you should first inspect the system and then take steps to remedy the problem. If you don’t feel confident that you can complete any of the steps given to correct the problem, it is always best to contact an HVAC professional for assistance.
In some cases, the clicking noise is created by the failure of the ignitor to light. This might be because your flame sensor has gotten dirty or your valve is faulty. Other reasons could be that a fan blade has gotten broken in some manner, your motor bearings have become too worn to function properly, or you have loose duct seams. In any case, a repeated clicking noise should be reason enough to call for immediate service. In some cases, the problem results in a gas leak, so it is best to have it inspected by a professional immediately.
Gas Furnace
Possible causes of a clicking sound coming from a gas furnace include the following:
Gas valve – This valve can become clogged or broken; gas can’t get through. The ignitor will click continuously as it attempts to light the system.
Flame Sensor And Thermocouple – Both of these components let the valve that allows gas to flow when it should open. If either is dirty or failing, it will fail to signal properly, and the ignitor will continue clicking as it reattempts to light gas that is not present.
Ignitor Flame – A weak flame may be too cool to ignite the gas it comes into contact with.
Fan Or Inducer – If a fan blade becomes broken, it can create a clicking noise that will continue until it is replaced.
Bearings – When motor bearings get too worn to perform properly, they will start to make a clicking noise.
Ductwork – If the clicking noise sounds as if it is originating in your ductwork, it could be a seam that has loosened or an object is obstructing the ductwork.
How To Stop Your Gas Furnace From Clicking
- The first thing you should check is whether you have gas. If there is no gas, then it is impossible for your furnace to ignite. Check your gas level to ensure there is adequate fuel in the tank.
- See if your furnace is getting gas through the gas line. A quick way to do this is to check other gas appliances and see if they are working. If they are, then the problem lies specifically with your furnace.
- Examine the gas valve to see if it is stuck. When the gas valve gets dirty, it can get stalled. Gently pushing the mechanism with the tip of a screwdriver may be enough to get it moving again. If this fails to correct the problem, you can use a multimeter to determine whether the valve is being powered sufficiently so that it can operate. If you aren’t comfortable with this or lack the proper tools, you can call an HVAC expert to help sort out the problem.
- Scrub the flame sensor. This sensor detects whether there is a flame in the furnace. If it can’t perform this operation, the built-in safety mechanism will shut off the system. An unclean sensor may not recognize a flame even when one is present. You will need to shut the power off to the furnace prior to taking out the sensor to clean it. Once you have done so, gently clean it with very light grit sandpaper.
- Verify the ignitor is functioning. Too little airflow from the inductor might mean that the pressure switch has failed or that the ignitor doesn’t have the power it needs for the furnace to light. You can test whether the ignitor is getting power with a multimeter.
- Make sure nothing is blocking the flue pipe and that the pressure switch has not failed.
- Draft inducer fan cleaning and calibration. Check to be sure there are no loose or grimy fan blades that may cause the clicking sounds. To properly clean these parts and verify that the blades are in good order, you will have to remove the fan for examination.
- Replace failed bearings. Once the draft inducer fan has been removed, you will be able to check the bearings in the blower. If they are worn-looking or have been damaged, they should be replaced.
- Lubricate any components that need it.
- Check your ducts for any cracks, split seams, holes, or obstruction
Electric Furnace
While most homeowners who complain of hearing clicking noises have a gas furnace, it is not unheard of to experience it with an electric furnace. Electric furnaces also have a starter system that can click as the unit kicks on, and this is nothing to be concerned about. Through continued clicking won’t put you in danger of a gas leak, but it should still be examined to prevent additional problems.
The most common reason for clicking from an electric furnace is split or cracked ductwork that needs repair or replacement or parts that have come loose and are clicking against other parts as the system operates. Because this system is electric, it is usually best to contact a professional to assess the situation and make any necessary repairs to eliminate the clicking noise you are hearing.
The only action you can really take yourself is to look for any loose parts or obstructions that may be causing a clicking noise. It might be as simple as having an object stuck in a register that is clicking against the metal of the vent as the heat moves it about. This is especially true in homes with small children who may drop or place objects in the openings.
Conclusion
In general, there are several reasons why a furnace can be constantly clicking. In the short term, you should also check your ductwork for any split seams or cracks that have developed; because there’s so much heat flowing through the ducts during warmer months, these problems are not an unusual occurrence and can be easily repaired with duct tape or sealants.
You can do this yourself if you are able to properly access the area and have the products you need, but in some cases, this will only be a temporary fix, and you will need a certified technician to make more permanent repairs or replacements, no matter what type of furnace you own.
