Air conditioner compressors usually fail due to one of two conditions: time and hours of operation (wear out), or abuse. There are some failures that could occur elsewhere inside the system which will cause a compressor failure, but these are less common unless the internal system continues to be substantially abused.
Usually abuse is known as a result of extended running with improper freon charge, and because of improper service along the way. This improper service can include overcharging, undercharging, installing the wrong 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 an system that had a major burnout without taking proper steps to remove the acid out of your system, installing the improper compressor (not big enough) for the system, or installing a fresh compressor on an system that had another failure that was never diagnosed.
The compressor can fail in exclusively some other methods. It might fail open, fail shorted, have bearing failure, or maybe a piston failure (throw a rod), or have valve failure. That's just about the entire list.
Whenever a compressor fails open, a wire contained in the compressor breaks. This is often unserviceable and also the symptom could be that the compressor will not run, though it may hum. When the compressor fails open, and implementing the steps here won't fix it, probably the system might be a good candidate for a new compressor. This failure causes no further failures and should not damage the remainder of the system; in case the rest of the 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 easy. Pop the electrical cover for compressor off, and take away the wires along with the thermal limiter. Using an ohmmeter, measure the impedance from a place terminal to a different one across all three terminals of a typical compressor. Also measure the impedance towards the case of the compressor for all those three terminals.
You should read low impedance values for those terminal to terminal connections (several hundred ohms or lower) and you ought to have a high impedance (several kilo-ohms or greater) for all terminals into the case (that's ground). If any of many 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 to the next terminal (which is able to be one of the terminals associated with the failed open). In such cases, the broken wire has moved and is contacting how it is. This condition - and that is quite rare though not impossible - could cause a breaker to trip and could result in a misdiagnosis of failed short. Be careful here; do an acid test of a typical 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 inside the compressor. This allows a wire on an motor winding to the touch something it should't touch - most likely itself a turn or two further along at 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 can 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 such a shorts occur, this is not immediately a hard short - therefore 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 subsequently, and such shudder shakes the winding such that you could separate the short. While the short posesses place, the present through 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 on your winding. Ultimately, the winding loses enough insulation that the surrounding the compressor is literally burning. This can only keep on for a few minutes however in at that moment the compressor destroys itself and fills the machine with acid. Probably the compressor stops. It may at that time melt a wire loose and short to the housing (which can trip your house main breaker) or towards the. If the initial cause of the failure was bad bearings causing the rotor to rub, then usually in the event the thing finally dies it will be shorted towards the housing.
Whether it shorts to the housing, it will blow fuses and/or breakers and your ohmmeter will show an extremely low impedance from one if not more windings to ground. Whether or not this does not short to the housing, and then it will just stop. You still establish the type of failure using an ohmmeter.
Do not directly diagnose an unsuccessful 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 attempt this by establishing the the ohmmeter gives normal readings, the starter capacitor is great, power is arriving along at 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 if possible. It's not worth fixing; its rich in acid thus is all junk. Further, an unsuccessful short happens to be initially attributable to other failure within the system that caused a compressor overload; by replacing the whole system you furthermore may will look to lose that potential other problem.
Less commonly, a compressor are going to have bearing failure, piston failure or perhaps 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 from un-repaired leaks). More rarely, they often signal another failure within the system say for example reversing valve problem or perhaps an expansion valve problem that winds up letting liquid freon get into the suction side of many compressor.
Should a bearing fails, usually you'll be safe in the knowledge for the reason that compressor will seem like a motor which has a bad bearing, or it will lock up and refuse to run. In the worst case, the rotor will wobble, the windings will rub in the stator, and you may wind up by using a failed short.
When 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 will shudder (very much like any stalled motor) so that the thermal limiter cuts it off. After you do your electrical checks, you will discover no clue of failed open or failed short. The acid test will show no acid. In this instance, you would possibly consider a hard-start kit however if the compressor has failed mechanically the hard-start kit won't obtain the compressor to begin. In such cases, replacing the compressor is an efficient plan long as the whole system is not decrepit. After replacing the compressor, you must carefully analyze behavior the entire system to determine whether the compressor problem was induced by something different.
Rarely, the compressor will experience a valve failure. In cases like this, it'll either sit there and appear to operate happily but pump no fluid (valve won't close), or it should lock up due to an inability to shift the fluid out from 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, after this you have no choice but to alter the compressor. Again, a system by using a compressor which includes had a valve failure is an efficient candidate for only a new compressor.
Now, when the compressor is mechanically locked up it could be as a result of the only a few things. In case the compressor is contained in a heat pump, check to see if 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 is not really 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 this is critical as positive clue of some failure in the system In addition to a compressor failure. Typically, it is metal fragments out of the compressor that clogs the filter. This might 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).
Author Resource:-
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. That 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 to have a second or so. 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 truly is worth trying whenever the transmissions for sale symptoms are as described.
![[Valid RSS feed]](http://article2008.com/images/feed-icon.png "XML Feed For RSS"){kind=icon}
![[Valid RSS feed]](http://article2008.com/images/icon_Rss.png "XML Feed For RSS"){kind=icon}
Category Rss Feed
Print This Article
Add To Favorites