Whether it’s a leaky furnace or if you flick the switch to start your heating system when the weather gets cold and it won’t start, common furnace problems can affect your home at any moment.

Regardless of the cause, learning how your heating system works and a little bit about some frequent furnace problems is crucial in deciding whether you can troubleshoot on your own or if you need professional assistance. 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 lack the necessary skills and tools, it's best to call a reputable HVAC company like Interstate Heating & Air Conditioning. We can accurately diagnose 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 frequent heating problems:

1. Your Furnace Leaks Water

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

It is imperative to address water leaks quickly to prevent more damage to your furnace. Consulting with a professional HVAC technician like the crew at Interstate Heating & Air Conditioning is recommended to diagnose and resolve the issue properly.

2. My Furnace Blows Cold Air/Lack of Heat

Some potential causes for a furnace blowing cold air or not blowing hot air are a malfunctioning thermostat, a problem with the pilot light or ignition system, a plugged 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 won’t blow hot air, it's best to contact a skilled HVAC technician to diagnose and fix the problem. They can provide an accurate assessment and recommend the correct solution.

3. My Furnace Is Not Keeping Up

A frequent reason your furnace isn’t keeping up on a cold day is that your home doesn’t have enough insulation, which can cause heat loss and reduced efficiency. Another reason your furnace is falling short is because it’s too small for your home, so it can’t make enough heat to completely warm the space. A malfunctioning thermostat or ductwork problems can also cause uneven heating.

To address this, first look at your home’s insulation level and make sure it’s enough to protect your home. Also, check the thermostat to make sure it’s set right and the batteries aren’t dead.

If the problem won’t go away, consider contacting an experienced HVAC company, such as Interstate Heating & Air Conditioning, 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 Isn't Running at All

If your furnace is not working, there are a few steps you can take to troubleshoot before calling a pro. Ensure the thermostat is set properly and the batteries are good. If the furnace still doesn't turn on, check the circuit breaker or fuse box to verify power is reaching the furnace.

If there is power but your furnace won't ignite, the problem may lie with the ignition system or gas supply. In that case, it's best to contact an experienced HVAC professional for diagnosis and repair.

5. My Furnace Turns On and Off

If your furnace is short cycling, it means it is turning on and off often at short intervals instead of running in regular cycles like it should. This can result in inefficiency, increased energy consumption and potential damage to your heating system.

If you believe your furnace is short cycling, the first step is to look at your unit’s air filter. Filters should be exchanged regularly to ensure air flow, so if your furnace air filter is dirty you should exchange it for a clean one—and ensure it is pointing in the right direction. Second, check your thermostat and verify  it’s set right and the batteries are good.

If those two things don’t work, it’s best to call experts like the staff at Interstate Heating & Air Conditioning. Immediate professional attention will help restore the proper functioning of your furnace and prevent more complications and high energy bills.

6. My Furnace Won't Stop Humming

When your furnace is making a humming noise, it often is a symptom of a malfunction with the electrical components or the blower motor. For this reason, if you hear your furnace making a humming noise, it is critical to take action.

If the noise persists, it is best to  contact a professional HVAC technician.

7. My Furnace Makes Loud Noises

If your furnace is producing a consistent loud noise, it's important to handle the issue quickly to prevent further damage or potential safety risks.  One common reason is a broken blower motor or fan, which can generate a grinding or screeching sound. Another common cause is a loose or worn-out belt that may make a squealing or rattling noise.

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

8. My Furnace Is Not Turning On

If your furnace won't turn on, make sure the thermostat is set to the preferred temperature, is in heating mode and the batteries are working. Then, verify that the circuit breaker or fuse that goes to the furnace is working right. If these basic checks don't resolve the problem, you can check 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 do the job, call a professional for furnace repair.

9. My Furnace Is on but Not Igniting

Like a a furnace that won't turn on at all, a furnace that isn’t igniting can be the result of a plugged air filter or a tripped circuit breaker. So, checking the air filter and looking over your circuit breakers are a good place to start.

Other common causes of a furnace not igniting could be a faulty igniter or faulty flame sensor. Indications of these include the furnace continually making an attempt to ignite without success, no heat production or the furnace is making a burning or gas smell. Both of these issues can be easily fixed by HVAC professionals like the team at Interstate Heating & Air Conditioning.