What happens
A request is not issued or is overridden by local settings, timers or controller logic.
Typical symptoms
No operation from the remote, unexpected stops or a unit that operates differently from the selected setting.
Checks that distinguish this cause
Check the supported local control path, remote batteries and actual displayed mode. Review timers, lock settings and documented delays before interpreting lack of compressor operation as a hardware fault.
What can look similar
A valid command can be inhibited by mode priority, protection or a system fault.
Repair direction
Restore the intended supported settings or replace a confirmed failed approved controller.
Verify the repair
Verify start, stop, mode and setpoint commands through the intended local interface.
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.