Its a Trane unit #YCD120C3LFA
never had one like this. first comp runs fine along with fan etc...
2nd stage wont start up. I replaced the Control board with a new one.
It will stage correctly when i jump it out in test mode
i was told the board controls the staging and the differential could be set on the board but it has not dip switches/jumpers on it
the low pressure switch is closed and does have adequate pressure in the lines, thats the only safety this thing has
it is wired into a trane tracker managment system, although ive never messed with one, i was told it shouldn't have anything to do with the unit staging, as it does come on with a call for cool