Eb
Indoor/Outdoor Wiring Polarity Error (S1, S2, S3)
Mitsubishi Electric · PAR-21MAA MA Remote Controller
What does Eb mean?
The wiring between the indoor and outdoor unit, specifically for the communication lines S1, S2, S3, has incorrect polarity. This prevents the remote controller from operating and causes 'PLEASE WAIT' to be displayed. The outdoor board LED will blink green twice and red once alternately after system startup.
Repair Steps
- 1
Verify the polarity of the S1, S2, S3 communication wiring between the indoor and outdoor units according to the system wiring diagram.
- 2
Correct any reversed polarity connections at the indoor and outdoor unit terminal blocks for S1, S2, S3.
Verified technical data. Last updated: March 2026
Source: Mitsubishi Electric PAR-21MAA MA Remote Controller