Error Code RED LED2 ON (solid)

Carrier 58MVP Error Code RED LED2 ON (solid): Microprocessor Malfunction

TL;DR
The microprocessor has malfunctioned. To reset: Put setup switch SW-1 in the ON position and jumper thermostat terminals R, W/W1, and Y/Y2 simultaneously with the door switch pushed in and power to the unit ON. Disconnect jumper and place setup switch in the OFF position. If LED2 reappears, replace the main control board.
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 RED LED2 ON (solid) Mean?

The microprocessor has malfunctioned. To reset: Put setup switch SW-1 in the ON position and jumper thermostat terminals R, W/W1, and Y/Y2 simultaneously with the door switch pushed in and power to the unit ON. Disconnect jumper and place setup switch in the OFF position. If LED2 reappears, replace the main control board.

Common Causes

Cause Likelihood DIY?
Internal microprocessor failure on the control board Most common ✗ Call a pro →
Power surge or electrical damage to control board Common ✗ Call a pro →
Control board date code earlier than 9405 Uncommon ✗ Call a pro →

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Carrier 58MVP Service and Maintenance Manual, p.11 – LED Codes