Hello all
I need some help with some motor control schematics.
so essentially need to install a timer that turns on a fan for 4 hours and then turns it off for 4 hours and vice versa. I am just having difficulty putting this all together.

I have a omron h3cr-a timer and I figured out how to wire that. Just need help figuring out how and where to add it to this schematic so I can wire it.

 

wire timer contacts across 19 and 20, removing 3-C and 88. Replace 3-O with a two position maintained selector. The danger is that a reset of a current trip may result in motor start unintentionally.

 

Post #2 does seem to be correct, and the caution is valid. But it seems that the motor contactor, "88" seems to have many more auxiliary contacts than are common.
The completely safe control scheme would add a control relay for the auto mode that sealed on through the overload contacts. Thus the "auto/timer mode would be enabled by another NO button and sealed through the same stop switch.. The Auto mode would enable the timer control, in series with those contacts, but be released by either an overload trip or the stop button..