Carrier 58RAV Furnace Controller Repair

The furnace was showing symptoms of shutting off within 45 seconds of the heat cycle. LED was showing three short flashes and one long (31). Based on the manual, the error code is "PRESSURE, DRAFT SAFEGUARD, AUX-LIMIT SWITCH (when used*) OR BLOCKED VENT SWITCH (when used) DID NOT CLOSE OR REOPENED".  Upon closer inspection of the controller board, the resistor at location R33 showed cold solder. Re-soldering the resistors fixed the problem.

 

 

Make sure to take a lot of picture, label the wires and reconnect the controller board properly.