This one is around the corner from me so I see it daily. Nothing wrong with the defrost system, just that it was left on 90 minutes and that doesn't cut it in our climate. When conditions get extreme like we had a few weeks ago, it gets overwhelmed and builds up like this. Finally the ice is off the coil but still little air gets through. Today we hit upper 30s and much of that is finally gone, for now.
Amazing however, to see units like this all over the place. Don't homeowners ever wonder why their unit looks like this? Or wonder why there is NO heat out of the pump? Or wonder why their electric bill suddenly went up?