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How To Lessen Vibration Noise In Your Heat Pump's Outside Unit

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Heat pumps are known to produce unusual noise during operation; for example, the reversing valve that causes the unit to transition from heating mode to cooling mode, or vice versa, can make a noticeable sound similar to rushing air. Even while not cooling or heating, a buzzing sound can normally be heard as the unit's low voltage solenoid idles. However, not all noises are normal and should be addressed. Fortunately, homeowners can easily fix the problem if vibration is the cause of outside unit noise. Below is more information on how you can quieten your heat pump's outside unit if vibration is causing it to operate loudly:

Tools and materials needed

  • Vibration isolation pads, quantity of four

  • Hex driver set

  • Garden hose with spray nozzle

  • Soft-bristled brush

  • Thread locking compound

Step-by-step procedure

1. Prepare for working safely on your unit - while an alert homeowner can correct many of the causes of excess noise in a heat pump's exterior unit, such as vibration, it is important to remember that all air conditioning and heating units carry hidden dangers that can injure or kill you. Below are some safety awareness issues to address:

  • Electricity - heat pumps and conventional air conditioners use 240 volts AC and electrical current at this voltage level can pack a wallop. Always turn-off your unit's main power by removing the disconnect handle from the outside box. Never attempt to open the housing of a unit that is still connected to live voltage.

  • Fan - the large, metal-bladed fan can also cause serious injuries. If it suddenly turns on while you are working, you can lose a finger or worse. Disconnecting the power also will prevent trouble, but keep in mind that strong winds can cause a fan blade to rotate fast enough to cut you.

  • Refrigerant - beware when working with refrigerant lines. They are under high pressure, and a sudden release of refrigerant can spray debris into your face. Be careful that you don't break soldered joints or bend copper lines.

2. Remove the housing - the first step to eliminate noise after disconnecting the power is to remove the outside unit's housing. It will be attached to the chassis of the unit via multiple hex-head screws. Use an appropriately-sized hex driver to remove these screws and set them aside. Carefully lift the housing up and away from the chassis; be careful not to cut any wires or damage any other components while removing the housing.

3. Inspect and clean the fan - inside the unit, you will see the fan, compressor and condenser coils. Take a close look at the fan and look for any lodged debris that might cause vibration. Also, check the blades themselves to look for objects that might unbalance the fan; for example, items such as a sap, insect egg cases, animal or bird droppings and other objects can adhere to the blades and cause it to be out-of-balance during operation.

If you locate such debris, then wash the fan blade thoroughly with a garden hose sprayer. Be careful not to aim the spray into electrical components or at the compressor. Use a soft-bristled brush to wipe away any type of matter that might be causing a problem.

4. Replace the housing - after inspecting and cleaning the fan, place the housing back on top of the unit while being careful not to damage wires or hoses. Place a drop of thread locking compound on each hex-head screw and screw them into their holes. Be sure the screws are firmly attached to the housing and chassis even though the thread locking compound will also help keep them from jostling loose.

5. Install vibration isolation pads - after ensuring your unit's internal vibration problems are addressed, you will need to install isolation pads to absorb excess vibration of the outside unit as it operates. These pads are simple to install, but you will need assistance.

To install, have a helper lift one corner of the outside unit. While the assistant holds up the corner, quickly slide an isolation pad under the corner and adjust it so it is centered. Lower the unit, and repeat the process at each corner. Turn on the unit, and carefully listen to to ensure the sounds are eliminated or reduced. For more information, check out sites like