A HVAC unit manufacturing method and a HVAC system are disclosed herein. In one embodiment, the HVAC system includes: a controller having control board terminals, a parallel wiring harness having a first and a second connection header, the first connection header coupled to the control board terminals, and a switch having terminals. The terminals of the switch including: a pair of functional terminals configured to indicate a status of the switch and a pair of jumpered terminals independent of the pair of functional terminals and internally connected together within the switch, wherein designated combinations of the terminals indicate a circuit configuration for employing the switch in the HVAC system with each of the terminals having a particular design that dictates a specific corresponding connection header be used for each of the designated combinations, wherein a single one of the designated combinations of the terminals corresponds to the second connection header.