Whether it’s a leaky furnace or if you flick the switch to turn on your heating system in the fall and it won’t start, common furnace problems can strike your home at any moment.

Regardless of the problem, learning how your heating system works and a little bit about some common furnace problems is essential in deciding whether you can troubleshoot on your own or if you need professional services. By monitoring the furnace's behavior, listening for strange noises and checking for signs of damage or blockage, you can narrow down the possible causes.

If you're uncertain about the problem or aren't equipped with the necessary skills and tools, it's best to call an experienced HVAC company like AC Sales. We can accurately identify the issue and complete the required repairs or maintenance, so we can get your furnace up and running ASAP.

Here's more about what causes a furnace to leak water and eight other common heating issues:

1. My Furnace Is Leaking Water

A furnace can leak water for a number of reasons. One possibility is a condensate leak, where the water released during the combustion process is not effectively draining away. This might be due to a clogged condensate drain line or a broken condensate pump. Another likely cause of water leakage from a furnace is a cracked heat exchanger, which can be responsible for water—as well as dangerous gases—coming out of the furnace.

It is important to deal with water leaks promptly to prevent further damage to your furnace. Contacting a professional HVAC technician like the crew at AC Sales is recommended to diagnose and resolve the issue effectively.

2. My Furnace Blows Cold Air/Not Blowing Hot Air

Some potential causes for a furnace blowing cold air or not blowing hot air could be a malfunctioning thermostat, a problem with the pilot light or ignition system, a clogged air filter, or a malfunctioning heating element. It could also be your furnace is overheating and shutting off as a safety measure.

If your furnace does not blow hot air, it's a good idea to contact a professional HVAC specialist to diagnose and fix the problem. They can give an accurate assessment and recommend the appropriate solution.

3. My Furnace Can't Keep Up

A frequent reason your furnace isn’t keeping up on a cold day is that your home lacks insulation, which can lead to heat loss and lower efficiency. Another reason your furnace is struggling is because it’s too small for your home, so it can’t make enough heat to adequately warm the space. A defective thermostat or ductwork problems can also produce insufficient heating.

To deal with this, first check your home’s insulation level and make sure it’s enough to keep warm air in and cold air out of your home. Also, examine the thermostat to make sure it’s set right and the batteries are working.

If the problem continues, consider contacting an experienced HVAC company, such as AC Sales, who can look over your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or modifying your thermostat settings.

4. My Furnace Is Not Working

If your furnace is not working, there are some steps you can take to troubleshoot before calling a professional. Make sure the thermostat is set properly and the batteries are not dead. If the furnace still doesn't start, check the circuit breaker or fuse box to verify power is reaching the unit.

If there is power but your furnace won't ignite, the problem may rest with the ignition system or gas supply. In that case, it's a good idea to contact a seasoned HVAC technician for diagnosis and repair.

5. My Furnace Turns On and Off

If your furnace is short cycling, this means it is turning on and off multiple times at short intervals rather than running in regular cycles like it ought to. This can cause inefficiency, increased energy consumption and potential damage to your furnace.

If you suspect your furnace is short cycling, the first step is to look at your unit’s air filter. Filters should be changed on a regular basis to ensure air flow, so if your furnace air filter is clogged with debris you should exchange it for a clean one—and be sure it is pointing in the right direction. Next, go to your thermostat and look to see if  it’s set right and the batteries are good.

If those two things don’t work, it’s best to call experts like the team at AC Sales. Quick professional attention will help restore the proper functioning of your furnace and reduce the chance of more complications and high energy bills.

6. My Furnace Won't Stop Humming

Whenever your furnace is making a humming noise, it often is a sign of problems with the electrical components or the blower motor. Therefore, if you notice your furnace making a humming noise, it is crucial to take action.

If the noise persists, it is best to  get in touch with a professional HVAC technician.

7. My Furnace Makes Loud Noises

If your furnace is making a persistent loud noise, it's important to deal with the issue right away to prevent further damage or potential safety risks.  One common cause of this is a malfunctioning blower motor or fan, which can generate a grinding or screeching sound. Another common cause is a loose or worn-out belt that may produce a squealing or rattling noise.

Given the complexity of furnace systems and potential risks involved, it's safer to consult with a heating and cooling specialist.

8. My Furnace Is Not Turning On

If your furnace refuses to turn on, make sure the thermostat is set to the right temperature, is in heating mode and the batteries are working. Then, verify that the circuit breaker or fuse controlling the furnace is sending power to the unit. If these basic checks don't resolve the problem, you can examine the furnace's power switch or emergency shutoff switch to ensure they're in the "on" position and weren’t accidentally turned off.

If those steps don’t get the job done, call a heating specialist for furnace repair.

9. My Furnace Won't Ignite

Like a a furnace not turning on at all, a furnace that isn’t igniting can be caused by a dirty air filter or a tripped circuit breaker. So, inspecting the air filter and looking over your circuit breakers are a good place to start.

Other common causes of a furnace not igniting are a faulty igniter or malfunctioning flame sensor. Signs of these include the furnace continuously making an attempt to ignite without success, a lack of heat production or the furnace is making a burning or gas smell. Both of these issues can be easily addressed by HVAC specialists like the team at AC Sales.