**First check the jumper between RH and RC.** On Hunter models with those terminals, a system with one R/RH supply wire needs that jumper—even with heating only. A missing jumper can leave the heating circuit working while the manual fan circuit has no power. Hunter’s manual specifically shows the jumper for a three-wire, heat-only system. [Hunter wiring instructions](https://image.hunterfan.com/43154.pdf)

The blower running during heating is consistent with this: a gas or oil furnace normally starts its own blower after warming up. Selecting **Fan ON** uses the separate **G** fan-control circuit. [Hunter fan-operation instructions](https://image.hunterfan.com/43154.pdf)

To check:

1. **Turn off power to the furnace** before touching the wiring.
2. Check your thermostat’s model-specific instructions and confirm the required **RH–RC jumper** is installed securely.
3. Check that the **G wire** is secure at the thermostat and connects to **G at the furnace**. Identify wires by their terminal connections; colors alone are unreliable. [Hunter installation manual](https://image.hunterfan.com/42707.pdf)
4. Restore power and try **Fan ON**.

If the jumper and G connections are correct, an HVAC technician can test the thermostat’s fan output and the furnace’s fan-control circuit.

What is the Hunter model number, and is there currently a jumper connecting RH to RC?