5,200 BTU unit. Compressor and fan both work when first turned on, then compressor quits after 5-10 minutes of operation. Won't turn on again even after 5-minute fan-on cool down. Process repeats after AC unit has been turned off for 10 minutes and re-started. Is this worth trying to fix, or should I replace the whole unit?

if the sensors are okay, it might be the compressor overheating, my portable ac (moretti elite ac) is also behaving the same, especially when i turn the fan to max. the compressor shuts down about 7 mins and turns on again in about 5 mins, now i found out when i turn to medium or low the compressor runs normally. i think when on medium or low setting some of the cool air directs/channels to the compressor thus cooling it more.

Before I even read that far into your post, I was thinking "thermostat" replace it...It seems to be failing badly. If you take it into logical perspective...normally the unit gets turned on, then takes a bit to get cold, then once it reaches its pre-determined temperature, turns the unit either "off" or just blows the fan...by kicking off the compressor. This unit you have is getting this cycle done within 5 minutes instead of a few hours...replace the thermo and you should be fine. Now if you could post the exact model number here I can go look up the part for you.

When you shut it off and back on it slugged the compressor if you turn it off and back on before the pressures equalize between the high and low sides it will slug the compressor and it will not run should let sit for five minutes or so before restarting. The humming is either the compressor making noise usually common for the compressor to make some noise or the fan motor bearings are getting bad on the outside unit. If the unit works normal probably not much you can do till it breaks if it is the compressor it is more economical to replace the whole unit if it is just the fan motor it is worth changing. You could take an amp draw on the fan motor and the compressor to see if the are within the limits on the name plate of the outside unit.

trying to get the compressor to operate. it could be a bad capacitor and the compressore wont start or maybe the compressor is burned up

For a refrigerator to operate properly, it must: 1) have power to it; 2) the compressor (underneath the unit) must run; 3) the compressor fan (close to the compressor) must turn; and 4) the evaporator fan (inside the freezer unit, usually behind an access panel) must turn.

These would be the first things to check.

Check outside unit if unit and compressor are running feel the large line to see if it is cold. If compressor is running and line is not cold possible charge problems. You may have a capacitor problem outside. they go out quite often. You can change this yourself, Open up outside unit and the cap is the silver bullet with terminals out the top. Bad cap can cause compressor to not operate and also the fan. You need to clean the coil inside or at leat check the coil to see if it is clean. You can clean theis with a toilet brush do not go against the coil bit brush with the fins. You may need to call a service tech but try these options first. russ

You do not say if it is outdoor or indoor fan which operates. However I presume all your filters are clean and the drainpipes are clear. The only other thing you could suspect is the thermostat or air flow sensor.

Check outside unit capacitor and the contactor.. I work on Goodman unit sounds like a cap or contactor

It is probably a failed run capacitor for the compressor. Without the capacitor, the motor can't even try to run, but it will draw extreamly high amperage until it trips the thermal overload (avarage trip time 5-10sec) after it has a few second for the safety to cool off, it will try again. Either that or the compressor truly is seized

before you go to fix it, what is the setting it is at? What is the tempurature of the room it is in? If the setting has been satified the unit has done it job and if it is too cold in the room it will not operate properly either.
Sgt 48