Error 181 — Simultaneous opening of cooling/heating MCU SOL V/V (2nd detection)

What does 181 mean?

This is a confirmed error (second detection) where both the cooling and heating solenoid valves in the MCU are open simultaneously. This is a critical fault indicating a severe refrigerant flow conflict.

• Persistent malfunction of a solenoid valve
• Hardware failure on the control board
• Deep-seated wiring issue causing incorrect valve activation
• Internal fault in the refrigerant system

Click steps to track your progress.

1. 1

   Immediately turn off the entire HVAC system at its main electrical panel.

2. 2

   Wait for an extended period (e.g., 15-30 minutes) to allow all components to fully cool down and reset.

3. 3

   Restore power and observe the system carefully for any recurring error messages or unusual operation.

4. 4

   This error strongly indicates a need for immediate professional intervention. Contact a certified HVAC technician.

5. 5

   Do not attempt to operate the unit if this critical error persists, as it could cause significant damage.