Calling Rheem meisters

does any one know the delta t (ambient vs coil temp) for Rheem.

3 ton 13 seer R22 package 72f indoor

i have changed defrost board (seems to work fine until hi humidity)and can still
see heavy frost on the coil for 45 min+ with OAT at 15f, by touching the
ambient sensor with snow it will go into defrost quickly making me curious about the delta t on the sensors.

Inquiring minds want to know
thanks for your support
db