I am looking for some way to detect an excessively iced dx evaporator coil. This is in a industrial freezer walk in unit that has a hot gas type defrost with a pressure switch termination. Problem is if we have door ajar or something, the coil wont get defrosted completely and begins to ice heavily. We have already lost 2 expensive coils due to freeze damage. I want some kind of sensor to lockout the unit if if shows too much ice. Measure temperature somewhere? pressure drop across coil?
Unit runs at -9C box temperature and uses R404
Thanks.