Why does punching an appliance sometimes seem to fix it?

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So I live in military barracks and i have a shitty fridge in my room. It started making this horrible noise, and out of desperation I landed a solid right hook to the side of it. Like magic, the noise stopped. This has happened numerous times in my life. Something is broken, and some brute force fixes it. What happens inside that could solve the problem from percussive force?

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19 Answers

Anonymous 0 Comments

Presuming it’s a fan rubbing on something, hitting it might knock it off/into a different position

Anonymous 0 Comments

Well. If it is a loud fan for example you may have knocked loose some dust or something that may have been contributing.

If it was a piece of plastic rattling you may have caused it to get wedged somewhere that stopped it..

You may also finish off whatever was dying. Again if it was a fan or something, the impact may have just killed it off.

Most of the time a light slam isn’t going to end up being the cure all, but it may be the end all.

Anonymous 0 Comments

You likely either cleared a blockage to the condenser fan or wedged it with whatever was causing the noise, preventing the fan from moving. Over the next few days I want you to place your hand on the areas between the doors, the strip between the freezer and fridge compartment is the most obvious place to check for fan blockage that doesn’t require a screwdriver. If it’s hot you need to unplug the fridge and call someone up because your fan is no longer cooling and this can cause a fire.

Usually, when an appliance is making a noise, it’s because something is loose and rattling around while the motor or fans are running and a quick slap can move whatever parts are touching for short amounts of time before it inevitably finds it’s way back to where it was before.

Anonymous 0 Comments

OP percussive maintenance is what you’re looking for. Sorry I’m not able to explain well, but I feel like you may appreciate the term to do some googling after. 🙂

Anonymous 0 Comments

Percussive maintenance is a thing, does it alaways work no, does it make you feel better yes.

Usually it helps with mechanical components. Something that was stuck that shouldnt be. Something that is out of alignment, something that should or shouldnt be grounded.

Its also usually the last ditch effort before you bin it. Knowing you have tried anything, and the last percussive maintrnance brings it to its death.

Anonymous 0 Comments

If its a wobbly worn out motor bearing or loose electrical connection, a solid whack could temporarily jostle the parts enough to either stop the noise or make the electrical connection again.

Anonymous 0 Comments

In aviation we have this joke: “if brute force doesn’t work you are not using enough”

Now, all in all, force is not the answer to a technical issue. But sometimes you can fix even computers with impacts. The real deal is that as a technician you are supposed to investigate why the impact fixed it, and do a permanete proper repair, or replacement.

Most common reasons:

Air systems: air is dirty, dust and moisture can build up substantially thick layers onto moving parts to the point of clogging the part or locking a moving part. A hit can temporarily fix it by making the layer fall off. Real Fix: disassemble and clean it.

Mechanical systems: sliding parts tend to erode one another, dents may be created by friction and the part jams. A hit will move the stuck part away fro the dent. Proper fix: replace the worn out surface.

Noises: devices are subject to vibrations, and thermal expansion. In both cases, parts will contact one another, and make noise. Kicking it may move a part to a new location and the noise is not generated anymore. Proper fix: open the device, install Teflon tape to limit the chafing of certain parts, easy to spot, chafing makes a black dust as residue, if you see two parts in contact with back dust around the spot, separate the two parts, determine if they need to be replaced, if not, install Teflon tape so they stil stay in contact but without generating noise or wear. If the noise comes from a fan, check the fan for contact with case, fix it, check fan balance, if off balance, replace it. If bearing are the problems, replace those. For thermal expansion noises, generally Teflon tape is ok. For parts that may be bent or secured to a new position, do it. Never bend pipelines unless you are trained for that type of lines.

Always separate wiring from casing if found chafing. You may find this while fixing something else. Don’t ignore it. You see it you fix it. Fires and sudden failures will occur otherwise. Sooner or later and generally by Murphy Law, exactly when you need that device the most. Separation for wires may be physically displace it away or by inserting Teflon tape or similar protection tape. Paper tape and electric tape do not offer any long term protection from chafing.

Computers: bad news, if kicking it does fix it, it means thermal stress have cracked some contact. Your kick just managed to move that diode or whatever back to contact. It will fail again and again. Replace. Unless you are a professional repair man, you can just replace the whole computer. For computer I mean anything. From an I-pad to a thermal sight or radio or a weapon’s computer. Computer will never go back to be reliable by brute force or field repair. Even the simplest fix needs a professional shop repair. Or you get an even less reliable computer out of it. I bet as a military you would agree that a serviceable bow is better than a rifle that fires one day but not another. Scrap that computer.

For military use: you probably have to follow what I say in the spirit of what I say, but use whatever substitute you can find. Common sense and a bit of genius can do the trick.

Example: My fix for a tractor with an awfullly old battery, and a semi functioning starter, was to simply remove the protection of the shaft-mounted cooling fan, hit the fan with a log while my mate was holding the start button. It worked until we got a new battery.

Anonymous 0 Comments

Generally speaking percussive maintenance is just hitting something when it’s not working. For something that might be jammed, a sudden impact can clear the jam. For a loose connection, sometimes a big hit can reposition the components into working.

Most times, however, it just breaks things worse.

Anonymous 0 Comments

I had s terrible loud fridge. Apparently the problem was a small plastic thing touching the Motorpumpe which caused the noise. Could have been fixed with a kick (;

Anonymous 0 Comments

Despite the myriad of amazing modern devices, a lot of the failures they can experience are very similar, and the “fixes” for those things are often simple and applicable to lots of different types of equipment.

For electrical connections, sometimes there may be a small bit of corrosion preventing continuous good contact, and a little movement might be all that’s needed to shake some corrosion away or move the contacts enough to temporarily get good electrical contact again.

For rotating equipment, there may be a slight misalignment causing rubbing or vibration, and a little mechanical agitation might be enough to jostle the offending rotating equipment enough to temporarily keep it from rubbing or vibrating.

In fluid systems, like your refrigerator, there may be some small blockage that temporarily impedes flow causing cavitation noises. Shaking the flow obstruction might break it free, restoring unrestricted flow and making the noise go away.

Some systems rely on little mechanical switches or devices to change how the system operates. Your toilet has a float valve that stops water going into the back of the toilet when level gets high enough, for example. Those things can get physically stuck sometimes, and a little shaking gives it just enough momentum to overcome friction or whatever is sticking it. This could be a valve like in your toilet, or a little electrical relay in your car, or any of a million different things.

There’s infinite different scenarios where physical force is the solution, these are just some generic ones I could think of off the top of my head. Generally speaking, none of these things are actually fixes. Whatever is causing the noise, vibration, rubbing, sticking or whatever will still need some actual fixing to make it permanently go away, but sometimes a little slug or kick will get it going for a bit longer and sometimes that’s all you need.