@Davidsf89 , the G wires control The indoor blower fan motor. When you have GL that is for low speed fan and when you have a GH that is for high speed fan. Most locations with this are typically in apartments. Most systems these days use a variable speed fan that is set by the HVAC contractor to the proper airflow for the system design. The Google Nest Learning Thermostats can support up to 3 fan speeds (L,M,H). It should be noted that when you use the multiple fan speed feature, you will give up other functions programable on the Y2. The Y2 terminal can be either Compressor Stage 2, or Fan Speed 2. Typically to redefine the Y2 to be Fan Speed 2, you need a certified Nest Pro to perform the installation and configuration.
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AC Cooling Wizard
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
