Air conditioner compressors usually fail due to one of two conditions: period and hours of operation (wear out), or abuse. There are some failures that could occur elsewhere within the system which will cause a compressor failure, but these are less common unless the system continues to be substantially abused.
Usually abuse is known as an are the effect of extended running with improper freon charge, or because of improper service as i progressed. This improper service may incorporate overcharging, undercharging, installing the wrong starter capacitor as a replacement, removing (instead of repairing/replacing) the thermal limiter, insufficient oil, mixing incompatible oil types, or wrong oil, installing the compressor on an system that had a big burnout without taking proper steps to remove the acid out of your system, installing the wrong compressor (not big enough) for the system, or installing a brand new compressor on an system that had some other failure that was never diagnosed.
The compressor can fail in exclusively a few other ways. It may fail open, fail shorted, have bearing failure, or even a piston failure (throw a rod), or end up with valve failure. That's pretty well the entire list.
Whenever a compressor fails open, a wire contained in the compressor breaks. This is often unserviceable and also the symptom is the factthat the compressor will not run, though it may hum. When the compressor fails open, and following the steps here won't fix it, probably the system might be a good candidate for only a new compressor. This failure causes no further failures and shouldn't damage the remainder of the system; in case the rest of the system is not decrepit and then it could be affordable to just imposed a new compressor in.
Testing for a failed open compressor is easy. Pop the electrical cover of the compressor off, and take away the wires and also the thermal limiter. Using an ohmmeter, measure the impedance from a place terminal to a different across all 3 terminals of your compressor. Also measure the impedance to your case of the compressor for all those three terminals.
It is best to read low impedance values for those terminal to terminal connections (several hundred ohms or even lesser) and you should have a high impedance (several kilo-ohms or greater) for those terminals to the case (that's ground). If any of many terminal to terminal connections is a very high impedance, you've got a failed open compressor. In very rare cases, a failed open compressor may show a low impedance to ground to the next terminal (which is able to be one of the terminals associated with the failed open). In cases like this, the broken wire has moved and is contacting the case. This condition - which is quite rare though not impossible - could potentially cause a breaker to trip and shall spark a misdiagnosis of failed short. Be careful here; do an acid test of your produce in the lines before deciding the best way to proceed with repair.
Each time a compressor fails short, what happens is the idea that insulation in the wires has worn off or burned off or broken stored by the compressor. This allows a wire on an motor winding to the touch something it should't touch - most typically itself a turn or two further along on the motor winding. This brings on inside of a "shorted winding" which can stop the compressor immediately and cause it to get hot and burn internally.
Bad bearings could potentially cause a failed short. Either the rotor wobbles enough to contact the stator, causing insulation damage that shorts the rotor either to ground or to the stator, or end bearing wear can allow the stator to shift above time until it begins to rub contrary to the stator ends or the housing.
Usually when one of these shorts occur, it's not immediately hard drive data short - therefore initially the contact is intermittent and comes and goes. When the short occurs, the compressor torque drops sharply, the compressor may shudder somewhat visibly subsequently, and such shudder shakes the winding such that you could separate the short. Even though the short posesses place, the current in the shorted winding shoots up as well as a lot of heat is produced. Also, usually the short will blow some sparks - which produces acid contained in the air conditioner system by decomposing the freon right into a mixture of hydrochloric and hydrofluoric acid.
Eventually (possibly a very few weeks, usually less) the shuddering and the sparking as well as the heat as well as the acid cause insulation to fail rapidly at the winding. Ultimately, the winding loses enough insulation which the surrounding the compressor is literally burning. This can only look for a few minutes but in at that moment the compressor destroys itself and fills sst with acid. Then a compressor stops. It may at that time melt a wire loose and short to the housing (what can trip your house main breaker) or towards the. In case the initial cause of the failure was bad bearings causing the rotor to rub, then usually in the event the thing finally dies it is shorted towards the housing.
If it shorts to the housing, it will blow fuses and/or breakers with your ohmmeter will show an extremely low impedance from one particular if not more windings to ground. Whether it does not short towards the housing, and then it will just stop. You still establish the structure of failure using an ohmmeter.
You cannot directly diagnose a failed short with an ohmmeter unless it shorts to the housing - a shorted winding won't come up who has an ohmmeter while it would having inductance meter (but who has just like some of those?) Instead, you should infer the failed short. You try this by establishing the the ohmmeter gives normal readings, the starter capacitor is great, power is arriving with the compressor, AND an acid test of the freon shows acid present.
By using a failed short, just give up. Change everything, including the lines probably. It's not worth fixing; it is packed with acid thus is all junk. Further, an unsuccessful short has been initially attributable to other failure in the system that caused a compressor overload; by replacing the whole system you also will look to lose that potential other problem.
Less commonly, a compressor are going to have bearing failure, piston failure or a valve failure. These mechanical failures usually just signal tire but could signal abuse (low lubricant levels, thermal limiter removed so compressor overheats, chronic low freon condition on account of un-repaired leaks). More rarely, they will be able to signal another failure within the system say for example a reversing valve problem or an expansion valve problem that winds up letting liquid freon enter into the suction side of the compressor.
Any time a bearing fails, usually you will have the comfort of knowing due to the compressor will appear to be a motor that has a bad bearing, or it'll lock up and refuse to operate. Within the worst case, the rotor will wobble, the windings will rub on the stator, therefore you will end up which has a failed short.
In the event the compressor locks up mechanically and fails to run, you will have the comfort of knowing as it will buzz very loudly for a few seconds and may even shudder (just like any stalled motor) before thermal limiter cuts it off. If you does your electrical checks, you will find no a history of failed open or failed short. The acid test will show no acid. In cases like this, you can try a hard-start kit but in case compressor has failed mechanically the hard-start kit won't receive the compressor to start out. In this instance, replacing the compressor is an excellent plan so long because the majority of this game's system is not decrepit. After replacing the compressor, you need to carefully analyze performance the complete system to determine whether the compressor problem was attributable to something else.
Rarely, the compressor will experience a valve failure. In such cases, it should either sit there and appear to perform happily and will pump no fluid (valve won't close), or it will of course lock up on account of an inability to relocate the fluid out of the compression chamber (valve won't open). Whether it is running happily, then after you have established that there's indeed loads of freon throughout system, but nothing is moving, then you definitely do not have any choice however to replace the compressor. Again, a system which has a compressor that has experienced valve failure is an excellent candidate for a new compressor.
Now, in the event the compressor is mechanically locked up it would be because of a very few things. If the compressor is on a heat pump, be certain the reversing valve is not stuck middle. Also check to see if the expansion valve is working; should it be blocked it could lock the compressor. Also check to see if the filter will not be clogged. I once saw a system that had a locked compressor resulting from liquid lock. Some idiot had "serviced" the system by adding freon, and adding freon, and adding freon until the thing was completely full of liquid. Trust me; which won't work.
Should diagnosis show a clogged filter, then the is critical as positive clue of some failure in the system Save for a compressor failure. Typically, it is metal fragments from the compressor that clogs the filter. This could easily only happen if something is creating the compressor to wear very rapidly, particularly within the pistons, the rings, the bores, along with the bearings. Either the compressor has vastly insufficient lubrication OR (and more commonly) liquid freon is obtaining on the compressor on the suction line. This behavior need to be stopped. Try to find the expansion valve and at the reversing valve (for a heat pump).
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Often air conditioner compressor cost a dated system experiences enough mechanical wear internally that it is "worn in" and demands more torque to begin with on the system load than could possibly be delivered. This system will sound very much like a car battery a locked bearing; the compressor will buzz loudly for a few seconds probably the thermal limiter will kill it. Occasionally, this system will begin right up in case you whack the compressor by using a rubber mallet though it is buzzing. This sort of system is a good candidate to have a hard-start kit. This kit stores energy and, in the event the compressor is told to do so start, dumps extra current directly into compressor for only a second or thereabouts. This overloads the compressor, but gives some extra torque to get a short time and it is often sufficiently to honor that compressor run again. I even have had hard-start kits give me an extra 8 or 9 years in a few old units that otherwise I'd have already been replacing. Conversely, I actually have had them give not very many months. It s your call, but considering how cheap a hard-start kit is, it is worth trying whenever the transmissions for sale symptoms are as described.
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