RESSAC commercial technician arrived at drug store in Porterville, CA, to perform quoted work on the walk-in cooler. The tech powered down the system, removed the original faulty defrost time clock and replaced it. Tested and verified unit operations, refrigeration equipment back to optimum temperatures and operations. Rite aid #5799 porterville came to out to change defrost clock for dairy cooler. Unit is on and fully operational at this time