Whether it’s a leaky furnace or if you flip the switch to power up your heating system in the fall 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 essential in deciding whether you can troubleshoot on your own or if you need professional services. By watching 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 not sure about the problem or lack the necessary skills and tools, it's best to call a reputable HVAC company like May's Heating & Air. We can accurately identify the issue and complete the required repairs or maintenance, so we can get your furnace working again ASAP.

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

1. Your Furnace Leaks Water

A furnace can leak water for many reasons. One possibility is a condensate leak, where the water created during the combustion process is not properly draining away. This might be due to a blocked condensate drain line or a failing condensate pump. Another possible cause of water leakage from a furnace is a cracked heat exchanger, which can lead to water—as well as dangerous gases—escaping from the furnace.

It is important to deal with water leaks promptly to prevent additional damage to your furnace. Contacting a professional HVAC technician like the crew at May's Heating & Air is recommended to diagnose and resolve the issue properly.

2. My Furnace Blows Cold Air/Lack of Heat

Some possible 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 blocked air filter, or a malfunctioning heating element. It also may be your furnace is overheating and shutting off as a safety mechanism.

If your furnace won’t blow hot air, it's better to contact a skilled HVAC technician to diagnose and fix the problem. They can offer an accurate assessment and recommend the correct solution.

3. My Furnace Is Not Keeping Up

A widespread reason your furnace isn’t keeping up on a cold day is that your home doesn’t have enough insulation, which can result in heat loss and decreased efficiency. Another reason your furnace is falling short is because it’s too small for your home, so it can’t produce enough heat to effectively warm the space. A defective thermostat or ductwork problems can also produce uneven heating.

To handle this, first assess your home’s insulation level and make sure it’s enough to insulate your home. Also, look at the thermostat to make sure it’s set right and the batteries are working.

If the problem lingers, consider consulting with an experienced HVAC company, such as May's Heating & Air, who can look over your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or adjusting 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 phoning a professional. Make sure 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 ensure 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 reach out to an experienced HVAC professional 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 is designed to do. This can lead to inefficiency, higher energy bills and potential damage to your heating system.

If you suspect your furnace is short cycling, the first step is to check your unit’s air filter. Filters should be exchanged regularly to ensure air flow, so if your furnace air filter is plugged with dirt you should exchange it for a clean one—and make sure it is pointing in the right direction. If that doesn’t do the trick, check your thermostat and make sure  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 May's Heating & Air. Immediate 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

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

If the noise doesn't go away, it is better that you  contact a professional HVAC technician.

7. My Furnace Is Noisy

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

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

8. My Furnace Can't Turn On

If your furnace will not 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 controlling the furnace is functioning properly. If these basic checks don't address the problem, you can examine the furnace's power switch or emergency shutoff switch to make sure they're in the "on" position and weren’t accidentally turned off.

If those steps don’t do the job, contact a heating specialist for furnace repair.

9. My Furnace Is Not Igniting

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

Other common causes of a furnace not igniting are a faulty igniter or nonfunctional flame sensor. Symptoms of these include the furnace repeatedly 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 addressed by HVAC specialists like the team at May's Heating & Air.