XV20i / XV18 EEV, LSOV and outdoor fan

Troubleshoot the XV20i / XV18 heat pump outdoor EEV (46 Ω stepper windings, symptom chart), the latching switch-over valve (7 Ω coil, 4 / 12 VDC pulses) and the ECM fan: 187–252 VAC supply, 15–18 VDC J9 signal, PWM bands.