Yellow wire = y = cooling wire Ford expedition radio wiring diagram. Unique Honeywell Smart thermostat Wiring Diagram diagram Heat pumps are different than air conditioners because a heat pump uses the process of refrigeration to heat and cool.while an air conditioner uses the process of refrigeration to only cool, the central air conditioner will usually be paired with a gas furnace, an electric furnace, or some other method of heating. Thermostat wiring diagram 4 wire . This is commonly found in standard hvac systems that use an air conditioner and a furnace. Purged ad scripts, tweaked target focus, and added tags. For instance , in case a module will be powered up and it sends out the signal of half the voltage and the technician does not know this, he would think he provides a problem, as he would expect the 12v signal. Obtaining from factor a to direct b. A button will certainly be a break in the line with a line at an angle to the wire, much like a light button you c...