A shoe store manager calls to report that the heat is off. This store has an electric heat package unit on the roof. The service technician politely introduces himself and his company to the customer. While maintaining eye con$-$ tact with the customer, the technician asks for the cus$-$ tomer's account of the problem. The service technician should always make customers feel like they are helping to find the solution to the problem. Once all of the cus$-$ tomer's questions are answered in everyday language the customer can understand, the technician puts on protec$-$ tive shoe covers and starts to troubleshoot. The technician uses the following checkout procedures to determine the problem. You can follow the procedure using the diagram in Figure $15\mathrm{.}36.$