I have a 4yr old side by side Whirlpool Ref/freezer. Approx 2 months ago, I noticed water on the floor, tracking it back to a frozen defrost drain. I chipped away the ice and poured hot water down the drain until it was free flowing.

Tonight, I had the same problem, 15min later, freeing up the clog.

There are several icing over issues on this forum, most of them relating to a clogged drain. My question is, what causes this?

Is my freezer set too cold? Do I have too much crap in the freezer? Do I have too much crap in my refrigerator? Are they any vents that are blocked in the refrigerator that affect the freezer? Any assistance would help, I went 4 years without a problem, now twice in 2-3 months.

I have a SubZero 550 top refrigerator, bottom freezer. The condensation drain hose builds up ice even after I defrost thoroughly, use a hair dryer and confirm its clear by seeing water go down it. Within a week it's iced up and the floor of the refrigerator begins to build up ice, freezing vegetables and causing uneven temperatures in the refrigerator. Also, ice then begins to build up on the freezer drawer slides below.

I have not cleaned the condensor. Any other possible causes?