My wife was cleaning our Frigidaire side-by-side last week and left the doors open long enough for the warning beeps to begin. After she closed the doors, however, the beeping continued. I unplugged the unit for about 10 minutes and then plugged it back in. The beeping had stopped. Unfortunately, so had the cooling.

We noticed that items in the freezer were getting mushy and things in the refrigerator were just not cold enough. So we took everything out, put it in coolers, and I began troubleshooting.

First - I pulled out the refrigerator and took off the back panel. I vacuumed and cleaned underneath and inside around the compressor and coils. It wasn't too dirty, but I figured it was worth a try.

Second - I checked the compressor fan...it was running.

Third - I checked the compressor...it was running.

Fourth - I checked the coils...they were warm.

Fifth - I checked the vents at the top of the refrigerator compartment and the bottom of the freezer compartment...there was sufficient airflow.

Sixth - I took the panels from the back of the freezer compartment and checked the recirculating fan...it was running.

Seventh - I checked the defrost heater...it had continuity.

Eighth - I checked the thermostat...it had continuity.

Ninth - I looked at the condenser coils and here is the issue! The top quarter of them is frosted over, but the bottom three-quarters is not. There is not an even amount of frosting on the coils.

But now I'm at the end of my abilities. I don't know what to do next. I simply replaced the panels in the freezer and left it plugged in and running. The freezer is set at 0 but running at 55. The refrigerator is set at 35 but running at 56.

This unit was purchased in January 2011, and the sticker says, "Manufactured: 11-10" (I think that is November 2010). Today is October 31, 2014. It is LESS than four years old.

Now what?

Does not sound good.

Yes, the compressor had been running for quite some time before looking at the evap coils. And they haven't changed since either.

I also just pulled out the unit again to make sure and, yes, the compressor is running and warm. It seems to me that, after troubleshooting everything else, it is low on refrigerant.

If there is a leak in the system:
* What causes that to happen in a fairly new unit?
* Is this any different than when my home's central air unit or vehicle's air conditioning system needs more refrigerant?
* Can I just add more refrigerant (like in my car) or does a licensed repairman need to do it (like in my central air unit)?