The E122 error is triggered by the indoor evaporator pipe temperature sensor, which is clipped directly onto the coil inside the indoor unit to monitor its temperature. When this sensor stops sending a usable signal, whether from an open or short circuit, the control board loses visibility of what the evaporator is actually doing.
This sensor plays a key role in preventing the coil from freezing over and in managing how the system cycles, so an E122 fault is treated as a safety shutdown rather than something to ignore. It typically points to either a dislodged sensor or a wiring fault rather than a major mechanical problem.
Send us the code and a photo of the display, and a Ford & Doonan technician will get back to you. Please don't reset the unit before you take the photo.
(08) 9331 8800