Trane heat pump compressor and outside fan do not start after being idle
I think I know what is going on (mostly).  the unit was running hot and it sometimes tripped when it stopped he overpressure or had a pressure spike as it turned off which tripped it.  I suspect the switch does not untrip once the unit sits and the pressure drops. tapping the switch reset it.  The reason the unit was running hot is that over time a mold/moss/dust layer had grown over most of the air handler; this was plugging the gaps between the fins and severely reducing the heat transfer efficiency.   I cleaned this off 5 days ago and thus far have not had to tap the high pressure switch.  One thing I cannot explain is that in my initial troubleshooting tapping the high temperature cutoff switch also started the unit but it only ran about 15 seconds and shut down; then tapping high pressure switch would start it.