4 Common Furnace Condensate Pump Problems & How to Fix?

Furnaces keep millions of Americans warm each winter, and while they are a necessity in some regions, they aren’t without their issues. Even the best furnace can have problems with a condensate pump, which can lead to a variety of issues sooner than later. While it’s easy to tell if a condensate pump is working, diagnosing other problems can be more challenging

Furnace Condensate Pump Doesn’t Work

One of the biggest issues with a furnace water pump is when they simply don’t work at all. It’s one of the easier issues to figure out, however, as it generally comes down to power or parts failure. If the pump is plugged into an outlet and not hardwired, check to make sure it’s plugged firmly into the socket.

For hardwired systems, you’ll want to make sure the switch for the pump is set to “On” and that no breakers have been tripped. A tripped breaker has caused plenty of homeowner headaches over the years and can lead to a costly, unnecessary visit from an HVAC technician.

If the system has power and no breakers have been flipped, you could have a larger problem at hand with the pump itself. Condensate pumps that don’t work can’t remove excess moisture from the furnace. If not corrected quickly, it can lead to water damage or mold.

Furnace Condensate Pump Keeps Running

A furnace condensate pump that keeps running and won’t shut off is the second most common homeowners’ experience. It’s also a problem that can be caused by multiple parts inside a condensate pump including the check valve, float, and lines.

Inside every condensate pump is a float which triggers a switch when the water level inside the holding tank reaches a certain level. Unfortunately, these floats can become stuck which makes a condensate pump run continuously. Floats can become hung because the area around the float is dirty, but also because of poor line placement inside the unit.

That same grime and gunk that can cause a float to become stuck can also clog up check valves in a condensate pump. Check valves can be easily cleaned and replaced, although some parts can be challenging to find on older models.

Furnace Condensate Pump is Leaking

Have you noticed water pooling around the unit? That can mean that the furnace water pump has a leak. Finding the source of the leak can be challenging on some condensate pumps, but is relatively easy on a furnace condensate pump.

The first area to check is the tank. You can remove it, take it to a sink and fill it full of water to check for a leak. If the reservoir is in good shape, it could be a problem with the condensate line used to discharge water. It’s a good idea to periodically check the lines on your system throughout the year to ensure blockages do not occur.

Do you have a piece of plastic PVC pipe for the drain line outdoors on your system? They are prone to blockages from general muck and debris to curious squirrels that hide nuts in drain pipes. If the line isn’t sloped properly or becomes clogged, water can back up under the A-Coil, overflow, and drip through the furnace to the floor below.

Furnace Condensate Pump Making Noise

Peculiar noise has always been a sign something is amiss with a furnace or air conditioning system. By design, a condensate will make a bit of noise but it shouldn’t be loud enough to be a distraction. If you’re thinking about insulating the area to cut down on noise, you definitely have a problem on your hands.

One common noise is whistling, which can be a sign of air leak within the pump. Gurgling can mean the pump is going bad or there is a clog somewhere in the line as well. Loose discharge fittings and other parts can cause noise, so it’s always a good idea to make sure everything is hand-tight on the pump.

In other cases, noise could be simply because it’s a poor quality pump or one with an issue that slipped through quality control. While you don’t see many noise complaints for this condensate pump from Little Giant, that’s not the case with budget-friendly models from other brands.

Furnace Condensate Pump Maintenance

Condensate pumps are designed to be reliable, but problems can occur regardless of how well-built the unit is. That’s where maintenance comes into play as stuck floats and blockages burn out plenty of condensate pumps every year or cause water damage.

We recommend inspecting the condensate pump on your furnace at least once a month so you can stop problems before they start. If you notice build-up in your lines or want to clean the pump every few months, nothing could be easier. You’ll only need a thin bottle brush that can fit into any lines on the system and some canned air to clear any blockages hidden to the naked eye.

  1. The first thing you need to do is shut off the power to the condensate pump. If it’s hardwired, you’ll need to cut power to the unit itself at the breaker box before attempting to clean the unit. Otherwise, simply unplug it from the power outlet.
  2. Disconnect the PVC tubing running to the pump. There will be a line that runs directly to the furnace and another that’s tied to the drain line. When the lines are removed, the pump will be free to clean as needed.
  3. Use canned air to blow through the PVC lines and clear any blockages. If the brush is small enough, you can run it through the lines as well to loosen any debris beforehand. If the PVC tubing looks damaged or worn, now is the time to replace it.
  4. Make sure the bottle brush is clean, and then use it on the openings where the tubing is inserted into the machine. This will clear any debris that has accumulated inside the openings for the discharge and intake lines.
  5. Take the reservoir and look it over for any damage or serious signs of wear. You can wipe any gunk out with a paper towel before rinsing it in a sink if you don’t have an outdoor hose with pressure.
  6. Take the pump itself and use canned air to remove anything that may be lodged near the switch assembly or in other nooks and crannies. You can then “rinse” the pump itself to remove any access debris, but don’t soak the motor. It only needs a light rinsing, not a complete bath.
  7.  Reattach the water reservoir and replace the tubing on the condensate pump. Be careful how far the tubing is inserted so that it does not interfere with the float inside the condensate pump.
  8. Connect the condensate pump back to the furnace making sure everything is tight and properly connected, and then restore power to the unit. If you want to test the pump to make sure it’s working for additional peace of mind, just follow these steps.


Now that you understand some of the common problems with a furnace water pump, you can set a course of action to prevent issues with the pump before they occur. Maintenance is key, although it’s important to keep the cost of repairs in mind as well with older models compared to the price of a replacement.

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications.

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