**The most likely cause is a missing jumper between RH and RC.** On many Hunter thermostats, RH supplies the heating circuit, while RC supplies the independent fan circuit. With power connected only to RH, the heat can work while “Fan ON” does nothing.

For a three-wire, single-transformer system like yours, Hunter’s instructions specify keeping the **RH–RC jumper installed**, with the existing wires connected to RH, G, and W/B. See the [Hunter wiring instructions](https://image.hunterfan.com/43154.pdf), page 3.

Turn off power to the furnace before checking or changing the wiring, and confirm the jumper arrangement in your exact model’s manual. Then restore power and try “Fan ON.”

The blower running during heating doesn’t prove the G connection works: the furnace can start the blower itself. If the jumper is already present, the next things to check are a loose G connection, whether that wire connects to G at the furnace, and the thermostat’s fan switch.