If a rise in spindle temperature is evident, it is likely that the chiller (refrigerator) is malfunctioning.
Check in sequence that:
The chiller pump works (just place a hand on the motor head to feel if it vibrates/turns, the machine must be on and NOT in EMERGENCY)
The liquid circulates freely and with an adequate flow (500ml/min). To verify this, simply detach the recirculation tube from the IN fitting of the chiller and insert it in a bottle to ascertain the abundance of the flow (the machine must be switched on and NOT in EMERGENCY)