Furnace has power but does not start any heating cycle; status LED shows solid ON or steady 0 code

Safety first: You are working around low-voltage controls, but the furnace also contains 120/240V circuits. Turn off power at the furnace service switch and breaker before removing panels.

This condition usually means the control is in standby and is not seeing a call for heat.

• Check thermostat settings: Verify the thermostat is set to HEAT and the set temperature is above room temperature.
• Check thermostat wiring: Remove the furnace blower door, locate the control board, and verify that the R and W terminals have low-voltage wires firmly attached. Look for broken or loose connections.
• Jump R to W: With power on and the blower door switch held in, temporarily jumper between R and W on the control board. If the furnace starts, the issue is likely the thermostat or thermostat cable.
• Inspect low-voltage fuse: Many Rheem boards have a 3–5A automotive-style fuse. If blown, replace with the same rating and inspect for shorts in thermostat wiring.

If the furnace still does not respond to an R–W jumper, the control board may be faulty and should be tested or replaced by a qualified technician.