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 strike your home at any moment.

Regardless of the cause, learning how your heating system works and a little bit about some typical furnace problems is essential in deciding whether you can troubleshoot on your own or if you need professional services. By noting 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 don't have the necessary skills and tools, it's best to call a professional HVAC company like Arizona Comfort Systems. We can accurately pinpoint the issue and perform 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 frequent heating problems:

1. My Furnace Is Leaking Water

A furnace can leak water for several reasons. One possibility is a condensate leak, where the water created during the combustion process is not properly 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—leaking out of the furnace.

It is necessary to correct water leaks promptly to prevent further damage to your furnace. Reaching out to a professional HVAC technician like the crew at Arizona Comfort Systems is recommended to diagnose and resolve the issue properly.

2. My Furnace Is Blowing Cold Air/Lack of Heat

Some likely causes for a furnace blowing cold air or not blowing hot air include 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 precaution.

If your furnace will not blow hot air, it's a good idea to contact a skilled HVAC technician to diagnose and fix the problem. They can give an accurate assessment and recommend the proper solution.

3. My Furnace Can't Keep Up

A common reason your furnace isn’t keeping up on a cold day is that your home doesn’t have enough 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 produce enough heat to adequately warm the space. A defective thermostat or ductwork problems can also result in inconsistent heating.

To correct 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 Arizona Comfort Systems, 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 contacting a professional. Check if the thermostat is set right 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 unit.

If there is power but no heat, the problem may lie with the ignition system or gas supply. In that case, it's best to consult a seasoned HVAC professional for diagnosis and repair.

5. My Furnace Turns On and Off

If your furnace is short cycling, that means it is turning on and off often at short intervals rather than running in regular cycles like it is designed to do. This can result in inefficiency, more energy use and potential damage to your unit.

If you believe your furnace is short cycling, the first step is to check your unit’s air filter. Filters should be switched out regularly to ensure air flow, so if your furnace air filter is dirty you should exchange it for a clean one—and be sure it is pointing in the right direction. Second, go to 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 Arizona Comfort Systems. Quick professional attention will help restore the proper functioning of your furnace and avoid further complications and high energy bills.

6. My Furnace Is Making a Humming Noise

If your furnace is making a humming noise, it often is an indication of an issue with the electrical parts or the blower motor. For this reason, if you notice your furnace making a humming noise, it is crucial to take action.

If the noise continues, it is a good idea to  contact a professional HVAC technician.

7. My Furnace Is Noisy

If your furnace is producing a constant loud noise, it's important to handle the issue promptly to prevent further damage or potential safety hazards.  One common reason is a malfunctioning blower motor or fan, which can create a grinding or screeching sound. Another potential cause is a loose or worn-out belt that may emit a squealing or rattling noise.

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

8. My Furnace Is Not Turning On

If your furnace will not turn on, make sure the thermostat is set to the right temperature, is in heating mode and the batteries are functioning. Then, check if the circuit breaker or fuse that goes to the furnace is functioning properly. 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 work, call an expert for furnace repair.

9. My Furnace Won't Ignite

Similar to a furnace that will not on at all, a furnace that isn’t igniting can be the result of a dirty air filter or a tripped circuit breaker. So, examining the air filter and assessing your circuit breakers are a good place to start.

Other common causes of a furnace not igniting include a faulty igniter or nonfunctional flame sensor. Indications 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 very easily solved by HVAC pros like the team at Arizona Comfort Systems.