Furnace will not start at all; no blower, no inducer, no LED lights

Electrical safety: You will be working near 120/240V circuits. Turn off the breaker before opening electrical panels.

• Check breaker: Locate the furnace breaker in the electrical panel. Reset if tripped. If it trips again immediately, there is a short that needs professional diagnosis.
• Inspect service switch: Verify the furnace service switch (often looks like a light switch near the unit) is in the ON position.
• Door switch: Ensure the blower door is properly installed and depressing the door safety switch.
• Check internal fuse: Many Rheem boards have a low-voltage automotive-style fuse. Replace only with the same rating if blown, and inspect thermostat wiring for shorts.

If power is present at the furnace but the control board remains dead, the board or transformer may be failed.