What happens
A sensor gives a plausible but inaccurate input because it has drifted or uses a different characteristic.
Typical symptoms
Poor temperature regulation, unusual modulation or protection with no obvious open-circuit fault.
Checks that distinguish this cause
Compare the input with an independent temperature reference at the sensing location and with the actual OEM curve. Confirm the replacement part identity rather than assuming all sensors with matching plugs are equivalent.
What can look similar
Room stratification or a remote sensing setting can create a real temperature difference rather than a failed sensor.
Repair direction
Fit the approved sensor or correct the verified sensing configuration.
Verify the repair
Verify readings and control response over representative temperatures.
Equipment-specific limits
Use the exact sensor curve, connector pinout and temperature reference. There is no universal mini-split thermistor resistance, test voltage or interchangeable code table.
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.
- Haier: Arctic Next Gen service manualAW/1U EH2VHD model examples of inverter, motor, sensor and circuit diagnostics; obtain the installed model manual.
Editorial review: 2026-09-29. Verify the current manual for the installed model.