In some embodiments, a process for manufacturing a diaphragm for an air admittance valve includes disposing a first center disk into a first cavity of a first mold, the first center disk includes a hollow stem. A first data packet is transmitted to the hearing device by the external unit. A hydraulic lifting cylinder moves the wheels downward relative to the fork assembly to raise the fork assembly into a towing position with the load substantially centered over the trailer’s wheels. When attached to the thermostat wires or the air handlers connector block, it allows the air conditioning system to be manually overridden, so as to determine and locate defects in the system. The mail operation supporting system receives the mail and the mail receiving form, determines postal fee, and reports result of receipt to the customer through the customer barcode supporting system. A WEC encompasses a functional block of an IC, an entire IC, or a device that includes a plurality of ICs.