Heat pumps do tend to makes strange and/or loud noises at times, more so in the winter. Heat pumps have reversing valves that reverse the flow of refrigerant between the heating and cooling modes. During the winter, whenever the heat pump goes into the defrost mode, this valve shifts. Along with that comes a "wooshing sound", which usually lasts for a couple of seconds. After that, the compressor sometimes sounds much louder than usual, almost a "tinny sound". After shutdown the refrigerant pressures equalize, during this period sounds can sometimes be heard, but this is normal. Another common loud sound is when the outdoor unit starts up or shuts off. Specifically, the newer "Scroll" type compressors tend to make a "back-peddling" type of noise on shutdown. And on start-up, they sometimes sound like an "out-of-balanced washing machine". Sometimes customers complain of a "buzzing" noise coming from the outdoor unit, even when it's not running. This is usually caused by the reversing valve solenoid coil.

It's usually a low voltage device (24 volts) and some are just louder than others - and in most cases, this is normal. If you are hearing a very loud "metal-hitting-metal" type of sound, the fan blades could be hitting something; possibly ice, or a wire, or tubing. Take a look and shut the unit off immediately. This almost always ruins the fan blades and possibly the motor as well. If a piece of copper tubing shifted and is being hit by the blades, they could cut a hole in it causing the refrigerant to leak out. If the fan blades bend or break, they can smash the aluminum fins and copper tubing on the coil - essentially ruining your outdoor unit. Then there are always the "vibration" type of noises, which may sound simple, but can be the most difficult to eliminate. Sometimes it is just a matter of installing rubber isolation pads under the unit. Sometimes the refrigerant piping is strapped too tightly to the joists or studs in the home. Sometimes it is in the unit itself and just cannot be eliminated.

Out of balanced or broken fan blades Low refrigerant charge - can cause gurgling sounds Bad reversing valve - passes refrigerant internally, makes hissing sound Buzzing contactor or noisy solenoid coil Outdoor unit iced-up, fan blades hitting ice (weather-related) Fan blades hitting some other obstruction Vibration due to loose parts. Vibration due to refrigerant piping being strapped too tightlyWindow units often shake or rattle older windows. Several factors can cause window air conditioners to vibrate and make distracting noises. Fortunately, many vibrations have easily remedied causes. If you can locate the source of vibration, you can lessen or alleviate it completely either by making your own repairs or having the unit serviced for less than the cost of a replacement unit. Check for a loose window pane by pressing lightly along the edges where the glass meets the wooden housing. If the glass moves or shifts under pressure from your fingers, secure it to the frame by caulking both the interior and exterior.

Use a caulking gun to lay a bead of caulk along the edges, then press the caulk into place by smoothing it with a moistened fingertip. will my home warranty cover my ac unitAllow it to dry for 24 hours to eliminate the window rattle. window ac unit horizontal windowLocate possible internal causes. how to replace ac unit fan motorUnplug the air conditioner and open the outer casing. Casing designs vary widely among manufacturers and models, so locate the screws or bolts holding yours in place by examining their locations and removing all the likely connectors. Once these are removed, gently pull the casing away from the rest of the unit. If it does not come loose, note where it resists removal and examine that area for additional screws or bolts.

The casing should come away from the unit with ease once you find and remove all the bolts. Locate the air compressor inside the window unit. The compressor is a roughly cylindrical component with no apparent exterior moving parts, usually located behind the control panel. The bolts holding the compressor in place are sometimes overtightened by the manufacturer for shipping, which causes the compressor's internal movements to vibrate the entire unit. Turn the bolts counter-clockwise with a wrench to loosen them slightly. Examine the fan blades. The fan can be thrown off balance by accumulated dirt or grease on one or more of the blades. When unbalanced, the fan causes a vibrating or shaking motion similar to that caused by an unbalanced laundry load on a spin cycle. Blades may also become warped or bent, which also upsets their balance. Clean the fan blades and, if necessary, bend them back toward their proper position to reduce fan vibrations. Consider having the compressor replaced if loosening the bolts does not significantly diminish vibrations.

Do not remove the compressor yourself, because improperly handled refrigerant can cause injury. Instead, take your window unit to a qualified technician for the repair. Universal Pneumatic & Electric Group Ships from and sold by Universal Pneumatic & Electric Group. 4 Pack of Anti Vibration Pads 4" x 4" x 3/4" All Rubber Vibration isolation pads Brinmar SBUHD Universal-Fit Air Conditioner Compressor Sound Blanket Wrap (#0421A) 4 Pack of Anti Vibration Pads 4" x 4" x 7/8" All Purpose Super Duty Blue Composite foam Vibration…These INDUSTRIAL pads are brand new rubber. manufactured only months before we ship them. Industrial strength rubber has a smell that lingers for a while. the smell goes away after a few weeks. To speed up this process, simply was them in soap & water. You cannot hurt these pads with any cleaning agent. Super Duty All Rubber Anti-Vibration Pads These pads are the waffle type. Pads are designed for all purpose indoor and outdoor use. #91,076 in Home Improvements (See top 100)

#261 in Home Improvement > Power & Hand Tools > Power Tool Parts & Accessories > Air Tool Parts & Accessories > Air-Compressor Accessories See all 36 customer reviews See all 36 customer reviews (newest first) Extremely pleased with these pads. The vibration passing through our terrace floor was dramatically reduced, and the noise almost completely eliminated! ok...strong odor, work reasonable well...steel spring encased in rubber works better, but cost considerably more.Just lift the compressor unit one corner at a time and slide under. Did not offer a lot of noise reduction but did eliminate some of the start-up 'bang' noise. really helped cut the noise level Rubber Baby Buggy Bumpers. Smell fades away in a couple of days. Removed the vibration down to 80% once installed Didn't make any difference, wasted my money They reduced the vibrations a little but did not eliminate them. The neighbors still wake me at 2 and 4 AM when they slam the car doors multiple times over a 30 minute period.