At 1ºC, Do Air Defrost is not enough?

[georgedvf]

Hello!

I'm having troubles with a Cooler at 1ºC (Set point) where air defrost appears to be not enough, it's a ***** system(R-22), a lot of ice is remaining even after I extended time and frecuency of defrost cycle. But I've seen a lot of coolers at 1ºC where air defrost was used and there was no such a problem.

Do you think there's a way to know what is causing this issue in my case and not at the other cases?

Thanks in advance!