On arrival, checked in with employee. She directed me to freezer #4. Found freezer #4 reading a box temp of 75deg. Took a K meter temp of -2.0. Turned unit off. Replaced box temp sensor with new sensor. Returned power to the unit. System turned on and immediately read a box temp of 22degs. It quickly fell to -3.5degs. Confirmed box temp with K meter. System is operating correctly now. Obtained signature on work acknowledgment.