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Furnace Making Dripping Noise? 4 Common Causes (+ Fixes)

Condensation forms on cold surfaces when your furnace is running, which is why the system is fitted with a condensate drain. When problems occur with this part of the furnace, you’ll hear the furnace making dripping noise. This could result in the water moving toward the system’s electrical components.

Your furnace is making dripping noise because you have a leak in the ducts and vents, the evaporator coil is frozen, the condensate drain is clogged, or you have a faulty condensate pump. Fixes include checking the vent for leaks, warming up the evaporator coil, and cleaning the condensate drain.

This article focuses on helping you find the issue behind the furnace making dripping noise. I’ll also explain how to fix the 4 most common issues so that your furnace is nice and quiet.

Leaks in the Duct and Vents

When your furnace is making a dripping sound, start by looking at the exterior parts first. Opening up the furnace is dangerous if you’re not used to working with electrical components — always start with the basics first. 

Many people don’t realize that leaks in the air vents can actually lead to condensation in the wrong areas of the HVAC system. This generally happens when one of the vents isn’t fitted correctly, causing air to escape and condensation to accumulate. When this happens, the water will start dripping in the ductwork. 

The condensation in these areas can lead to problems down the line. Failure to attend to the issue can lead to liquids running toward the blower motor and the furnace’s main compartments. 

How To Fix

Walk along the lines where your ductwork and vents are located. Try to pinpoint the location of the dripping sound. Once you find the specific location, you’ll first inspect the vents’ exterior in this area:

  • You want to look for openings in the vents. 
  • Make sure you focus on the areas where multiple duct lines connect. These are common areas for leaks to occur. 
  • If you do find a leak in the vent, try to see why the leak developed. If the connection is problematic, reposition the vents so that they attach more securely. 

If the leak isn’t due to a misalignment of the connections, you should consider a different solution. This includes installing a new duct pipe in the area where you detect the leak. 

The Evaporator Coil Is Frozen

We tend to use the furnace during cold winter months. Temperatures can drop significantly in some parts of the country. During these frigid times, parts of the HVAC system may freeze up. 

To be more specific, the evaporator coil can freeze because it collects moisture. When this happens, you’ll hear a dripping sound from the melting ice.

Sometimes, people also report seeing drops of water come out of the vent when the evaporator coil is frozen. 

The issue is more likely to occur if you don’t turn on your furnace frequently. As the outside temperature drops, the coil begins to freeze. 

How To Fix

The ice on the evaporator coil is likely to clear up on its own – but while this is happening, you’ll hear dripping sounds. So, you should implement a few steps to keep your system safe. 

If the furnace is turned on, the heated air will melt the ice faster. Ensure nothing is blocking the condensate line. The condensation will be drained through it. As the ice melts, you’ll hear the dripping noise subside. 

The Condensate Drain Is Clogged

The condensate line is responsible for draining any liquids that accumulate inside the furnace. It’s a critical element that prevents water from reaching the electrical components of the HVAC system. The line consists of multiple parts. As the furnace runs, debris builds up in the condensate drain and other parts of the draining unit. 

This eventually leads to a clogged drain. When the condensate drain is clogged, it means water pulled in from the pump has nowhere to go. The water will continue to accumulate in this area, resulting in more condensation inside the furnace unit. As the water has nowhere to go, it starts dripping.

How To Fix

If there’s a blockage in the condensate drain, you need to clean it manually. This will ensure condensation in the furnace and vents can be effectively removed from the system — it also prevents water damage to the internal components of the HVAC. 

Your first step is to locate the condensate assembly. You should see pipes running from the furnace toward an external drain. These are the condensate pipes — a series of pipes that fit into each other. This makes it easier to disassemble the line to see where a clog may be.

Here’s what you need to do:

  1. Switch the furnace off. 
  2. Remove the line that runs directly toward the drain trap. See if something is clogging the line at this location. 
  3. Check the other pipes that are part of the condensate system. A clog can occur at any location throughout these pipes. 

This video will help you find the condensate drain and clean it thoroughly:

A Faulty Condensate Pump

If the previous fixes didn’t solve your problem, you should inspect the condensate pump. This pump is responsible for pulling in condensation from the ductwork and the vents. As the condensate is pulled in, the pump pushes the liquid toward a trap. The trap catches the liquids, ensuring the components in the furnace aren’t damaged. 

There are a few problems that can affect the condensate pump. It might be dirty in some cases, but it could also be faulty. 

How To Fix

The specific fix for this issue depends on why the condensate pump is having trouble operating normally:

  • If the pump is simply dirty and cannot pull condensate from the vents, you can clean it. A thorough cleaning should help restore proper functioning. 
  • If nothing is blocking the pump, the pump may be faulty. If you’re unsure if the problem lies with a faulty pump, ask a professional to test it. People who work with HVAC systems have the appropriate tools to test the pump quickly and see if it’s causing problems. 

A replacement condensate pump is the most effective solution in most cases. You can replace the entire assembly or just the pump, depending on what your budget allows. 

Here’s a video showing the steps involved in the replacement of a condensate pump:


Dripping sounds in a furnace could signify a developing problem, leading to water damage and other complications if you don’t attend to the issue. A furnace making dripping noise often experiences problems with the condensation unit. 


  • Jake Alexander

    Jake is a freelance writer from Pennsylvania who enjoys writing about science and sports. When he's not writing for Temperature Master, he can be found watching the NFL or playing basketball with his friends.

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