The intermittent cool air puffs/(start noise) into Frig. from upper vent have been happening for several months but frig. seemed cold enough/OK.
Recently, frig was no longer cold (now 50 deg F). Freezer is however cold.

Found massive ice buildup on evap. coils yesterday, cleaning off ice did not result in colder air in frig.

Any help w/diagnosis would be appreciated.

Also, How can I manually get system into defrost cycle??

Thanks for your help