Midea M2OC-18HFN1-M Service Manual page 88

9.4.2.15 The cooling operation or heating operation does not operate.
Supposed causes
Check of 4-way, please refer to part 5 in 9.5 Trouble Criterion Of Main Parts.
9.4.2.16 When cooling, heat exchanger of non-operating indoor unit frosts.
When heating, non-operating indoor unit get warm.
Supposed causes
Check of EXV, please refer to part 6 in 9.5 Trouble Criterion Of Main Parts.
● 4-way valve faulty
● EXV faulty
● Wire and tubing connected in reverse.