SP3.0 in 2016 and following SP3.1 in 2017 models require two included sensors to be connected to the small JST plugs on the right side. The SunPump will not allow a start up without both these NTC 10K ohm 1% 3950 sensors being detected by the PCB Motherboard.
If you see E5 (Panel), or E6 (Air) Error that means the sensors are not found, either missing or loose. Connect or test with a Multi-meter.
SunPump uses the Air Temperature measurement for several functions, and the Panel measurement for the Defrost purpose. See the Attached PDF page from the Installers Manual on Sensors for more details.
A work-around in startup is to use a jumper to complete the circuit from a NTC 10K ohm resistor. A service tech jumper is available on request by mail,, and should be part of an installers tools in case the Air and Panel sensors get lost. This will produce a steady state 25 C / 77 F. reading on the display parameters.
In new construction, the installer would staple up the 20-26 gauge 2 conductor wires for the outdoor Air and Panel sensor locations. Ambient Air thermistor should be under a soffit to avoid direct Sun, and Panel Defrost sensor needs to reach a panel at the refrigerant entry (smaller - 1/4" diameter pipe).
