10 Feb

Air Conditioner Compressor – More FAQ’s..

Air conditioner compressors usually fail as a result of one of two conditions: time as well as hours of operation (wear out or abuse. There are several failures that can occur elsewhere in the system that will cause a compressor failure, however these are more uncommon unless the system has been substantially abused.

Usually abuse is a result of extended running with improper freon charge, or as a consequence of improper service in the process. This improper service may include overcharging, undercharging, installing the incorrect starter capacitor as an alternative, removing (as opposed to repairing/replacing) the thermal limiter, insufficient oil, mixing incompatible oil types, or wrong oil, installing the compressor over a system which had a major burnout without taking proper steps to get rid of the acid through the system, installing the wrong compressor (not big enough) for the system, or installing A/C Compressor on a system which had a few other failure that was never diagnosed.

The compressor can fail in just a handful of different ways. It could fail open, fail shorted, experience a bearing failure, or a piston failure (throw a rod), or experience a valve failure. That is really the complete list.

Whenever a compressor fails open, a wire in the compressor breaks. This is unserviceable and also the symptom is the fact that compressor does not run, even though it may hum. When the compressor fails open, and after the steps here does not correct it, then this system may be a good candidate for a new compressor. This failure causes no further failures and won’t damage all of those other system; if the remainder of the system is not decrepit then it will be economical to just put a new compressor in.

Testing to get a failed open compressor is easy. Pop the electrical cover for the compressor off, and take off the wires and the thermal limiter. Utilizing an ohmmeter, look at the impedance from one terminal to another across the 3 terminals from the compressor. Also measure the impedance towards the case from the compressor for those three terminals.

You ought to read low impedance values for many terminal to terminal connections (a couple of hundred ohms or less) and you ought to have a superior impedance (several kilo-ohms or greater) for those terminals to the case (which can be ground). If any of the terminal to terminal connections is definitely a high impedance, there is a failed open compressor. In very rare cases, a failed open compressor may show a minimal impedance to ground from a single terminal (which will be one of many terminals related to the failed open). In this case, the broken wire has moved and is contacting the situation. This problem – which can be quite rare but not impossible – might lead to a breaker to trip and could result in a misdiagnosis of failed short. Be cautious here; do an acid test from the contents of the lines before deciding the best way to proceed with repair.

Each time a compressor fails short, what happens is the fact insulation on the wires has worn off or burned off or broken inside the Showerhead. This permits a wire on a motor winding to touch something it ought to not touch – most frequently itself a turn or two further along on the motor winding. This results in a “shorted winding” that will stop the compressor immediately and make it heat and burn internally.

Bad bearings may 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 permit the stator to shift down over time until it begins to rub from the stator ends or even the housing.

Usually when one of these brilliant shorts occur, it is not immediately a difficult short – meaning that initially the contact is intermittent and comes and goes. Each time the short occurs, the compressor torque drops sharply, the compressor may shudder a little visibly as a result, and this shudder shakes the winding enough to separate the short. While the short is within place, the current from the shorted winding shoots up and lots of heat is produced. Also, usually short will blow some sparks – which produces acid inside vqxigq air conditioner system by decomposing the freon into a mixture of hydrochloric and hydrofluoric acid.

Over time (possibly a couple of weeks, usually less) the shuddering and the sparking as well as the heat and also the acid cause insulation to fail rapidly on the winding. Ultimately, the winding loses enough insulation that this inside the compressor is burning. This can only go on for a couple minutes however in that period the compressor destroys itself and fills the device with acid. Then this compressor stops. It could during that time melt a wire loose and short for the housing (which can trip your house main breaker) or it might not. If the initial cause of the failure was bad bearings resulting in the rotor to rub, then usually once the thing finally dies it will be shorted towards the housing.

If it shorts to the housing, it is going to blow fuses or breakers and your ohmmeter shows a really low impedance from a number of windings to ground. If this does not short towards the housing, it will just stop. You continue to establish the sort of failure utilizing an ohmmeter.

You cannot directly diagnose a failed short with an ohmmeter unless it shorts to the housing – a shorted winding won’t show up with an ohmmeter even though it would with the inductance meter (but who has one of those?) Instead, you have to infer the failed short. You do this by establishing the the ohmmeter gives normal readings, the starter capacitor is great, power is reaching the compressor, Plus an acid test in the freon shows acid present.

With a failed short, just give up. Change everything, like the lines if at all possible. It is really not worth fixing; it is full of acid and for that reason is all junk. Further, a failed short might have been initially induced by some other failure in the system that caused a compressor overload; by replacing the whole system in addition, you will remove that potential other problem.

Less commonly, a compressor will have a bearing failure, piston failure or perhaps 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 because of un-repaired leaks). More rarely, they can signal another failure within the system like a reversing valve problem or an expansion valve problem that winds up letting liquid freon enter into the suction side from the compressor.

If a bearing fails, usually you will understand because the compressor will seem to be a motor using a bad bearing, or it will lock up and refuse to perform. Inside the worst case, the rotor will wobble, the windings will rub on the stator, and you will definitely end up with a failed short.

If the compressor locks up mechanically and fails to operate, you will understand since it will buzz very loudly for a couple seconds and may shudder (as with every stalled motor) up until the thermal limiter cuts them back. Once you do your electrical checks, you can find no proof failed open or failed short. The acid test will show no acid. In this case, you might use a hard-start kit but if the compressor has failed mechanically the tough-start kit won’t obtain the compressor to start. In cases like this, replacing the compressor is a great plan so long as the remainder of the product is not decrepit. After replacing the compressor, you must carefully analyze the performance from the entire system to figure out whether or not the compressor problem was induced by something different.

Rarely, the compressor will experience a valve failure. In cases like this, it will either sit there and appear to run happily but will pump no fluid (valve won’t close), or it is going to lock up due to an lack of ability to move the fluid from the compression chamber (valve won’t open). Should it be running happily, then after you have established that there is definitely a lot of freon within the system, but there is nothing moving, then you definitely do not have choice but to alter the compressor. Again, a system with car which includes experienced a valve failure is a great candidate to get a new compressor.

Now, in the event the compressor is mechanically locked up it may be because of a couple of things. If the compressor is on the heat pump, make sure the reversing valve will not be stuck midway. Also ensure the expansion valve is working; when it is blocked it could lock the compressor. Also ensure the filter will not be clogged. I remember when i saw a system which had a locked compressor as a result of liquid lock. Some idiot had “serviced” the device with the help of freon, and adding freon, and adding freon till the thing was completely packed with liquid. Believe me; that will not work.

Should diagnosis show a clogged filter, then this ought to be taken as positive evidence of some failure within the system OTHER than a compressor failure. Typically, it will likely be metal fragments out of the compressor that clogs the filter. This can only happen if something is bringing about the compressor to put on very rapidly, particularly in the pistons, the rings, the bores, and also the bearings. Either the compressor has vastly insufficient lubrication OR (and much more commonly) liquid freon is to get into the compressor on the suction line. This behavior must be stopped. Consider the expansion valve as well as at the reversing valve (for any heat pump).

Often an old system experiences enough mechanical wear internally that it is “worn in” and needs more torque to begin up against the system load than could be delivered. This technique will sound just like one with a locked bearing; the compressor will buzz loudly for a few seconds then the thermal limiter will kill it. Occasionally, this method will begin right up in the event you whack the compressor using a rubber mallet while it is buzzing. This kind of system is a great candidate for a hard-start kit. This kit stores energy and, when the compressor is told to start out, dumps extra current in to the compressor for any second roughly. This overloads the compressor, but gives some extra torque for any short time and is often enough to help make that compressor run again. I actually have had hard-start kits produce an added 8 or 9 years in some old units that otherwise I could have been replacing. Conversely, We have had them give just a few months. It is actually your call, but considering how cheap a difficult-start kit is, it really is worth trying when the symptoms are as described.

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