What happens
The electrical association or controller assignment does not correspond to the refrigerant circuit serving a head.
Typical symptoms
One room calls but another coil changes temperature, or a newly added zone behaves unpredictably.
Checks that distinguish this cause
Safely map indoor unit identifiers, cable destinations and actual piping to the approved port layout. Use the model pairing or automatic-check procedure where provided; avoid changing assignments by guesswork.
What can look similar
Shared capacity and minimum modulation can create mild effects in idle zones without crossed connections.
Repair direction
Correct the verified circuit assignment or installation defect through the approved commissioning process.
Verify the repair
Test zones individually and together and confirm each command affects the intended circuit.
Equipment-specific limits
Ordinary heat-pump multi-splits may not heat and cool different zones simultaneously. Heat-recovery VRF has a different architecture. Minimum head counts, capacity ratios and port rules vary.
Practice this diagnosis
This cause is a reference topic; it does not yet have a dedicated simulated call. Browse the practice board.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- Senville: R-454B model documentationSeparate installation and service documents for indoor styles and multi-zone generations.
- GREE: GREE communication-fault diagnostic guidanceA GREE-specific example of wiring and board fault isolation; E6 is not a universal code.
Editorial review: 2026-09-29. Verify the current manual for the installed model.