Air conditioner compressors usually fail on account of 1 of 2 conditions: both time and buisness hours (degrade), or abuse. There are a few failures which could occur elsewhere inside the system that may cause a compressor failure, but these are less common unless sst has long been substantially abused.
Usually abuse is usually a result of extended running with improper freon charge, and a consequence of improper service along the way. This improper service can include overcharging, undercharging, installing the improper starter capacitor instead, removing (as an alternative to repairing/replacing) the thermal limiter, insufficient oil, mixing incompatible oil types, or wrong oil, installing the compressor on a system that had a major burnout without taking proper steps to get rid of the acid coming from the system, installing the improper compressor (too small) for your system, or installing a fresh compressor on a system that had another failure or a never diagnosed.
The compressor can fail in only some other methods. It might fail open, fail shorted, experiencing a bearing failure, or maybe a piston failure (throw a rod), or have valve failure. That may be just about the complete list.
Each time a compressor fails open, a wire included in the compressor breaks. This is certainly unserviceable along with the symptom could be that the compressor won't run, while it may hum. In the event the compressor fails open, and implementing the steps here does not fix it, later the system can be quite a good candidate for a new compressor. This failure causes no further failures and must not damage the remainder of the system; if the whole system is not decrepit in that acse might possibly be economical to simply create a new compressor in.
Testing to get a failed open compressor is simple. Pop the electrical cover for compressor off, and get rid of the wires along with the thermal limiter. Using an ohmmeter, measure the impedance to the next terminal to a different one across all three terminals of a typical compressor. Also measure the impedance towards the case of the compressor for those three terminals.
You should read low impedance values for all terminal to terminal connections (a number of hundred ohms or lower) and you ought to have a high impedance (several kilo-ohms or greater) for all terminals into the case (which is certainly ground). If any of the terminal to terminal connections is an high impedance, you have a failed open compressor. In very rare cases, a failed open compressor may show a low impedance to ground from one particular terminal (that may be among the terminals involved with the service failed open). In such cases, the broken wire has moved and it is contacting how it is. This kind of migraines - and that is quite rare but not impossible - could cause a breaker to trip and could result in a misdiagnosis of failed short. Be cautious here; do an acid test of a typical veggies growing in the lines before deciding how to go ahead with repair.
Every time a compressor fails short, what happens is because insulation on the wires has worn off or burned off or broken inside the compressor. This allows a wire on a motor winding in touching something it must not touch - most likely itself a turn or two further along at the motor winding. This results in a "shorted winding" which is able to stop the compressor immediately and cause it to heat up and burn internally.
Bad bearings can cause a failed short. Either the rotor wobbles such that you can contact the stator, resulting in insulation damage that shorts the rotor either to ground or to the stator, or end bearing wear can allow the stator to shift more than time until it begins to rub the actual stator ends as well as housing.
Usually when such a shorts occur, this is not immediately a tough short - basically initially the contact is intermittent and comes and goes. Every time the short occurs, the compressor torque drops sharply, the compressor may shudder a lttle bit visibly as a result, which in turn shudder shakes the winding enough to separate the short. As the short is in place, the present through the shorted winding shoots up plus a great deal of heat is produced. Also, usually the short will blow some sparks - that generates acid included in the air conditioner system by decomposing the freon inside mixture of hydrochloric and hydrofluoric acid.
After some time (possibly a couple of weeks, usually less) the shuddering as well as the sparking and also the heat and also the acid cause insulation to fail rapidly on your winding. Ultimately, the winding loses enough insulation that the inside of the compressor is literally burning. This would only keep on for a couple minutes however in this point the compressor destroys itself and fills the machine with acid. Later the compressor stops. It could at the moment melt a wire loose and short into the housing (that may trip your home main breaker) or it may not. If the initial reason behind the failure was bad bearings causing the rotor to rub, then usually whenever the thing finally dies it will be shorted to the housing.
Whether it shorts into the housing, it'll blow fuses and/or breakers and your ohmmeter will show an incredibly low impedance from one or higher windings to ground. Whether or not this doesn't short to the housing, in that acse will just stop. You continue to establish the type of failure using an ohmmeter.
Do not directly diagnose an unsuccessful short which includes an ohmmeter unless it shorts into the housing - a shorted winding won't show up with an ohmmeter although it would who has an inductance meter (but who has one of those?) Instead, you will have to infer the failed short. You attempt this by establishing the the ohmmeter gives normal readings, the starter capacitor is useful, power is arriving at the compressor, AND an acid test of your freon shows acid present.
Which has a failed short, just quit. Change everything, that include lines if possible. This is not worth fixing; its rich in acid and hence is all junk. Further, an unsuccessful short happens to be initially due to some other failure within the system that caused a compressor overload; by replacing the whole system you furthermore may will have burn that potential other problem.
Less commonly, a compressor will have a bearing failure, piston failure or even a valve failure. These mechanical failures usually just signal wear out but could signal abuse (low lubricant levels, thermal limiter removed so compressor overheats, chronic low freon condition from un-repaired leaks). More rarely, they can signal another failure inside the system for instance a reversing valve problem or an expansion valve problem that winds up letting liquid freon enter into the suction side of the compressor.
Should a bearing fails, usually you'll be safe in the knowledge due to the compressor will appear to be a motor which has a bad bearing, or it'll lock up and refuse to run. Within the worst case, the rotor will wobble, the windings will rub in the stator, and you may wind up which has a failed short.
In the event the compressor locks up mechanically and fails to run, you'll be safe in the knowledge since it will buzz very loudly for a couple of seconds and may even shudder (just like any stalled motor) before thermal limiter cuts it off. After you do your electrical checks, you will notice no a history of failed open or failed short. The acid test will show no acid. In cases like this, you can consider a hard-start kit however if the compressor has failed mechanically the hard-start kit won't obtain the compressor to begin. In this case, replacing the compressor is an efficient 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 a result of something.
Rarely, the compressor will experience a valve failure. In cases like this, 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 due to an inability to shift the fluid out of the compression chamber (valve won't open). If it is running happily, then once you have established that there is indeed a lot of freon inside the system, but nothing is moving, then you have no choice however to replace the compressor. Again, a system by using a compressor that has experienced valve failure is an efficient candidate for a new compressor.
Now, when the compressor is mechanically locked up it would be because of an only a few things. In case the compressor is contained in a heat pump, be certain the reversing valve will never be stuck halfway. Also check to see if the expansion valve is working; if it's 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 machine by adding freon, and adding freon, and adding freon before 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 out of 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, and also the bearings. Either the compressor has vastly insufficient lubrication OR (and many more commonly) liquid freon starting to get into your compressor in the suction line. This behavior should be stopped. Focus on the expansion valve and at the reversing valve (for only a heat pump).
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Often air conditioner compressor cost a dated system experiences enough mechanical wear internally that must be "worn in" and it needs more torque to start out against the system load than may well be delivered. This strategy will sound very much like one with a locked bearing; the compressor will buzz loudly for a few seconds probably the thermal limiter will kill it. Occasionally, this strategy will begin right up in case you whack the compressor with a rubber mallet even though it is buzzing. This sort of system is a good candidate to get a hard-start kit. This kit stores energy and, when 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 limited time and it is often such that you can take that compressor run again. I actually have had hard-start kits give me an extra 8 or 9 years in some old units that otherwise I would have been replacing. Conversely, I actually have had them give only some 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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