DIY Tips From the Warner Service Blog

4 HVAC Things that Go Bump in the Night

Posted by Warner Service on Oct 29, 2015 9:31:29 AM

Halloween is not the time to worry about your HVAC system.

You should only have to worry about your candy supply lasting through the night, or if your child’s costume fits.

However, those screeching, rattling, banging and humming noises keeping you and your family awake at night should not be ignored. To help you determine the type of noise and how to fix it, here is Warner Service’s handy guide to HVAC things that go bump in the night:


A quiet rush of air is reasonable to hear from the ductwork, but if you hear a hiss, this means the coolant is leaking and the ducts are improperly sealed. This requires immediate attention from an HVAC team.

Heat pump:

If you hear a trumpeting or hissing sound from the compressor motor when you shut down the heat pump, it may be due to a leaky internal refrigerant valve. Check with a specialist to schedule an appointment for repair.

Indoor furnace:

This appliance can make a number of unsettling noises due to all of its components and parts. Each troubling sound means something different is wrong, so here is the breakdown:

  • Squealing or screeching means that the furnace’s belt and/or motor bearing is having problems. These issues can be solved with the simple addition of the correct lubricating oil or an inexpensive repair from a professional.
  • Rattling sounds are the worst for HVAC systems. This means that a piece of hardware in the motor system is coming loose or the motor may be failing. The solution is to call a professional before any disconnection occurs or further damage is done.
  • Banging noises indicate that you need to shut off your entire furnace because a large part of it needs to be checked out by an expert and replaced immediately.
  • A “thwapping” sound is typically indicative of something getting stuck in the fan blades. This problem is not dangerous, but it could hinder the longevity of the system’s motor, so carefully shut off the blower and remove the roadblock.
  • Clicking sounds are typically heard when turning the system on and off. However, if it is coming from the control panel or outside compressor, you may need to reset the system.
  • Vibrating noise from your furnace sounds similar to an out of balance washing machine because the motor is most likely off balance. This is not a devastating issue to your furnace, but it should not be ignored. Call a specialist as soon as possible.
  • If you have a gas or oil-fired system, and you hear an unusual rumbling sound associated with combustion, call for service immediately.

Outdoor air conditioning unit:

  • This appliance comes with a safety grate to prevent damage, but a sudden loud rattle could mean a small piece of debris got stuck in the compressor fan. To fix it, turn off the unit and remove the visible obstruction. After removal, check for any damage done to the condenser coils, compressor and fan. If anything is bent, call a professional for repairs.
  • A buzzing sound means that your unit is just wearing down from time, so you should begin looking for a replacement.

With Halloween right around the corner, the only thing that should be going bump in the night is your little one trying to sneak a piece of candy before bedtime. If you do hear any part of your HVAC system going bump in the night, use the glossary above to determine which part it is and how to fix it.

If a do-it-yourself solution is not your style, feel free to enlist the help of an expert. Contact Warner Service today.

Contact Warner Service

Topics: HVAC