Consult authorities having jurisdiction before installation. There isn't a low pressure switch (safety) so that sensor circuit needs to be jumped closed as a low pressure safety will open the circuit when below operating range. Dallas, Texas, USA RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE These instructions are intended as a general guide and do not supersede local codes in any way. Likely not much of an issue in So Cal at all but just something to keep in mind if the supply air gets super cold all of a sudden in the winter. With that disconnected and that thermostat with the brown leads energizes the defrost, you'd get some nice super cold air as the system will switch into AC to defrost the coil and no secondary heat source to temper the air. When the temperature of the outdoor coil rises high enough to causes the defrost thermostat to open, the defrost cycle will be terminated.

The unit will continue to run in this mode until the defrost cycle is completed.

The reversing valve is energized and turns on the electric heater(s).

Which temp sensor did you wire from the L and 24v? One (brown leads) is the defrost thermostat (initiates defrost when too cold and turns it off when warmed up) and the other thermostat is a little odd with its location being a thermal switch on the discharge line (typically you'd see a pressure switch for either a safety or for condenser fan cycling).ДЄlso, do you have any reheat in the fan coil? When fully wired, the W terminal would energize the reheat during the defrost cycle if the thermostat is calling for heat. The defrost board supplies 24 Volts AC to O and W2. I finally got a chance to look at all this (crazy day at work).

Lennox defrost board test