Outdoor unit circuit board error 11. Error occurrence condition:
Communication between control printed circuit board and communication printed circuit board of outdoor unit isn't performed correctly.
2. Relevant operation
1) Current operation is continued. Error is displayed on LED of outdoor unit.
2) If error is kept for 90 seconds since error occurs, new communication error (1F) occurs.
3. Clearance
The communication between control printed circuit board and communication printed circuit board of outdoor unit is performed correctly.
Possible causes:
1. Effect of extraneous noise:1. When power is turned off, and turned on again:
1) If error doesn't occur, printed circuit board is normal. Then, remove noise sources near outdoor unit.
2) If error occurs again, remove noise sources and take measure with the following countermeasure No.2 and 3.
2. Outdoor unit communication PC board insertion is faulty.2. Check the insertion of outdoor unit communication printed circuit board.
3. Printed circuit board is faulty.3. Replace printed circuit boards with the following procedure, and check the operation.
(1) Replace outdoor unit communication printed circuit board
(2) Replace outdoor unit control printed circuit board
Your only "fault" in this is for not following procedure exactly as said in manual. It could save you one (much more expensive) PCB.;)