CH outdoor temperature was invalid.
1. Outdoor sensor not connected.
2. Outdoor sensor wiring.
3. Faulty sensor
1. The CHS is factory set with Outdoor Reset enabled. Connect outdoor sensor or disable Outdoor Reset.
2. Check wiring of outdoor sensor. Wires should connect to SENSOR inputs “OUTDOOR” and “COM”.
3. Check sensor. Should be free of ice and snow. Check resistance of sensor and compare to thermistor resistance chart.