If you don't have a fridge sensor set up, The heater and cooler PID will act on the beer sensor.
I run on only a beer sensor, with the room temp sensor monitoring the glycol temp.
Without a fridge sensor, the fridge PIDs will take the input from the beer sensor as fallback.
My settings are
Beer-to-Fridge: Kp=0, Td=0, Ti= 0. This will make the fridge setpoint the same as the beer setpoint.
Heater1: 4s period, Kp= 60, Ti=3600, Td=120
Cooler (pump): PWM period of 120s, 10s min ON time. Kp=10, Ti=3600, Td=120