Error Code LED Continuous OFF

Carrier 58MVC Error Code LED Continuous OFF: No Power

TL;DR
Your Carrier 58MVC furnace has no power. The most common cause is a tripped circuit breaker or a power switch that was turned off — check both before calling a technician.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code LED Continuous OFF Mean?

When the amber LED on the furnace control board is completely off, it means the board is receiving no electrical power at all. The control needs both 115 VAC line voltage (at terminals L1 and L2) and 24 VAC transformer voltage (at SEC-1 and SEC-2) to operate. Without power, the furnace cannot respond to any thermostat calls.

This is one of the most straightforward codes to troubleshoot because it usually points to something outside the furnace itself — a tripped breaker, a turned-off power switch, or a door panel that isn't fully seated (which disengages the door safety switch). Less commonly, it can indicate loose wiring connections or a failed transformer, which require professional diagnosis.

If you recently had a power outage or someone was working near the furnace, start with the simplest checks first. The furnace power switch looks like a standard light switch and is typically mounted on or near the furnace or on a nearby wall.

Common Causes

Cause Likelihood DIY?
Tripped circuit breaker or blown fuse ✓ DIY fix →
Power switch turned off ✓ DIY fix →
Loose or disconnected power leads ✗ Call a pro →
Defective door switch ✗ Call a pro →

How to Fix It: Check Power Supply to Furnace

âš  Safety First
Always turn off the furnace at the power switch or breaker and shut off the gas supply before beginning. Do not proceed if you smell gas — leave the area and call your gas company immediately.

What You'll Need

Steps

  1. Turn off power at the breaker and shut off the gas supply valve Locate your electrical panel and find the breaker labeled for the furnace. Turn it to the OFF position. Find the gas shutoff valve on the gas line leading to the furnace and turn it to the closed (perpendicular to the pipe) position. If you smell gas, leave immediately and call your gas company.
  2. Check the circuit breaker Look at the breaker for the furnace in your electrical panel. If it has tripped (in the middle position or toward OFF), flip it fully OFF first, then back to ON. If the breaker trips again immediately, do not reset it again — this indicates an electrical fault that requires a professional.
  3. Check the furnace power switch Find the power switch on or near the furnace. It looks like a standard light switch and is sometimes labeled. Make sure it is in the ON position. This switch is commonly bumped off accidentally, especially in tight utility closets.
  4. Check the blower door panel The 58MVC has a door safety switch that cuts power when the blower access panel is removed. Make sure the panel is fully seated and latched. Press it firmly — even a small gap can disengage the switch.
  5. Restore power and gas, then verify Turn the gas supply valve back to the open position (parallel to the pipe). Turn the breaker back ON. The amber LED on the control board should now be visible through the sight glass on the blower access panel.
How to Verify
Look through the sight glass on the blower access panel. If the amber LED is now continuously ON (solid), the furnace has power and is in standby mode (code-on). Set your thermostat to call for heat and confirm the furnace responds.

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Carrier 58MVC Series 100 Troubleshooting Guide, p.8