What happens
The system uses an unintended sensing location or incompatible command configuration.
Typical symptoms
Room overshoots or never reaches the expected temperature despite conditioned air at the head.
Checks that distinguish this cause
Determine whether the head, wired controller, remote sensor or supported external interface supplies the temperature reference. Compare that location with an independent reading and the actual setup.
What can look similar
Air stratification and placement can create a true difference between sensed and occupied-zone temperatures.
Repair direction
Correct the approved sensing and interface configuration, or repair the verified sensor or placement fault.
Verify the repair
Verify comfort and controller response at the intended sensing location over a representative cycle.
Equipment-specific limits
Use supported controllers and interface modules. A Wi-Fi failure is separate from indoor/outdoor communication; do not jumper unidentified mini-split terminals or infer a conventional 24 VAC thermostat connection.
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.
- Daikin: 17 Series service manualModel-specific sensor and control examples; terminal values and code definitions vary.
- Senville: R-454B model documentationSeparate installation and service documents for indoor styles and multi-zone generations.
Editorial review: 2026-09-29. Verify the current manual for the installed model.