Ruud UGRA-07EMAES Error Code LED Off: No Power to Control Board
What Does Code LED Off Mean?
The IFC has a power LED that lights whenever line voltage and the low-voltage transformer are feeding the board. If it's completely dark, the board isn't powered, and nothing — inducer, igniter, or blower — will operate.
The most common reasons are the simplest: the furnace's own power switch (which looks like a light switch on or near the unit) was turned off, or the furnace circuit breaker tripped. A door-interlock switch that cuts power when the access panel is removed can also leave the board dark if the panel isn't fully seated. Beyond those, a failed low-voltage transformer or a dead IFC will keep the power LED off, and those need a technician.
A dark power LED is the opposite of the steady status LED that signals normal operation — with no power there's no status blink to read at all, so a dead LED is diagnosed by restoring power first, not by counting blinks. If power is later confirmed present at the board but the status LED still won't light, the IFC itself is the suspect.
What You'll Notice
- The furnace is completely dead — no inducer, no blower, no response to the thermostat.
- No lights at all on the control board through the viewing window.
- The thermostat may go blank if it draws its power from the furnace.
- The furnace breaker is in the tripped (middle) position, or the furnace switch is off.
Common Causes
How to Fix It: Restore Power: Check the Switch and Breaker
What You'll Need
Steps
- Shut off the gas supply and confirm power before you start Before working around the furnace, shut off the gas supply valve, and if you ever smell gas, leave immediately and call your gas company from outside. Because the board is already dark, the safe next step is to check what feeds it: locate the furnace power switch (a standard wall switch on or near the unit) and note whether it is on or off.
- Turn the furnace switch on If the switch was off, turn it on and watch the control board window for the power LED to light. It's easy to mistake this switch for a light switch and leave it off by accident.
- Check the circuit breaker At the electrical panel, find the furnace breaker. If it's tripped (in the middle position), switch it fully off, then back on. If the power LED lights, you're done.
- Make sure the access panel is fully seated Many furnaces have a door-interlock switch that cuts power when the panel is off. Confirm the blower-compartment panel is fully closed and latched so the interlock is engaged.
- Don't keep resetting a breaker that trips again If the breaker trips again right away, stop. A repeatedly tripping breaker signals an electrical fault that needs a technician, not another reset.
When to Call a Professional
Contact a licensed HVAC technician if:
- The power LED stays dark after the furnace switch is on and the breaker is reset
- The furnace breaker trips again immediately after being reset
- There is a burning smell or scorch marks at the board or transformer
- The board's status LED still won't light even though power reaches the furnace
Frequently Asked Questions
Why is my Ruud UGRA furnace completely dead?
The control board isn't getting power. Most often the furnace switch is off or the breaker tripped; less often the transformer or board has failed.
Where is the furnace power switch?
It's usually a standard wall switch on or right next to the furnace, sometimes at the top of the basement stairs. It's easy to mistake for a light switch.
The breaker keeps tripping — what should I do?
Don't keep resetting it. A breaker that trips repeatedly indicates an electrical fault that a qualified technician should diagnose.
Could a blown fuse on the board cause this?
Some furnaces have a low-voltage fuse on the control board; if it's blown, the board can go dark. Replacing it and finding why it blew is best left to a technician.
Sources
✓ Verified against manufacturer service manual — March 2026