Cooling OK, but pinging and short alarm sounds. Removed panel—it is the alarm making the noise, but there are no codes or visual alarms on the control panel inside the refrigerator compartment (RC). Put the unit into Diagnostic Mode per instructions by using the control panel in the RC. I verified that everything was working properly (e.g., the compressor ran, the condenser fan ran, etc.). The only oddity was that when I put in the code (03) to test the evaporator fan, the control panel flashed oddly and froze up. I did verify, however, that the evaporator fan came on. I was able to bypass the code for the evaporator fan to check that everything else worked (it did).
I tried resetting the alarm, turning the whole unit off for 10 minutes, etc. No luck—still have the pinging alarm.
Any ideas? I guess it could be the evaporator fan going bad, but I see no symptoms of this other than the odd behavior when I was in diagnostic mode.