When I clean under the SxS Whirltag I usually vacuum the equivalent of another whole cat out!  Parents have the same fridge as I do and it's the same way.  My previous one (basically same fridge) had the coils underneath in a straight pattern that I could fit the plastic Kirby crevice tool in between to clean.  My parent's and my current one have the coils in a zig zag formation...but not positioned the way to easily slide a vacuum attachment through.  So there's really no way to clean them aside from turning the fridge on its back and getting it from the bottom...not happening.

Effective as compressed air may be, the mess it causes is simply not worth the huge clean-up effort that would involve every last inch of my kitchen.   As Letterkenny hero Wayne would say, "Hard no."

Our 2009 KA Architect SxS has the Z-fold condenser, which KA/WP claim never needs cleaning/vacuuming.  I don't buy it, and once or twice a year I do the best job I can with the crevice tool.  I can see how the Z-fold arrangement causes the front of the condenser to capture most of the dust, leaving the portion behind it fairly clear of any accumulation, so that may be the reason for advising the coils never need cleaning, but reduced air flow is an inevitable side effect.   Another more likely reason would be that WP wants to sell more refrigerators.

With the fridge now ten years old, I feel that staying on top of the condenser's dust accumulation is a good way to keep the compressor from working any harder than it has to.  I like the fridge and its features too much to replace it sooner than is necessary.

My sister had to replace the compressor on her Maytag Wide-by-Side due to never vacuuming the condenser that supposedly never needs vacuuming.  The problem is, she almost never has fewer than two cats living with her.  She killed the original compressor by following Maytag's advice.  Her home warranty coverage took care of the repair, but I think she learned her lesson.  The fridge is still running.

For a fridge with coils on the back, I'd not ever bother cleaning them.  That's a passive system that doesn't attract anywhere near the amount of dust a forced draft system does.

Good point, Tom. 

If a fridge with coils on the back is shoved into an enclosure (with clearances that allow for circulation), I can see how dust would accumulate more readily.  In that case, it makes sense to vacuum once in a while.  That your friend's fridge had been running since the mid-'80s without ever having been vacuumed seems to suggest that every 20 years might be enough.

My vintage Penncrest upright freezer also uses the cabinet instead of a condenser.  I had never heard of such a system until I bought the freezer last year.

I have a basic top freezer Whirlpool model, about 9 years old.  I had to replace the compressor start relay this summer and cleaned the coils for the first time.  They were filthy and I immediately noticed that the refrigerator ran less.  Of course Whirlpool would rather people just buy new ones.

I wish they had some kind simple air filter like dehumidifers and window A/Cs that could be easily removed and rinsed off.