Where is the blower motor relay switch?

The blower motor relay switch—often integrated directly onto the main electronic control board or integrated furnace control module—is located inside the main blower compartment of your indoor air handler or gas furnace. To locate and access this relay safely, you must first turn off the electrical power to the indoor unit at your home's main circuit breaker panel, then remove the front service access panel or door of the air handler. Once the compartment is open, look at the main electronic control board where low-voltage and high-voltage wires converge; on older systems, you may find a standalone mechanical relay box with screw terminals, while modern systems use soldered board relays. You can verify its location using the wiring schematic. Never touch internal components while power is active.