I need some help. This is my first wshp ive worked on. the problem is the unit cuts on for about 30 seconds then shuts off like its tripping pressure switch. i checked the normal things high pressure switch, low pressure switch. i call tech support for help and according to them the board is indacating low temp switch which i bypassed. same problem still. installers did not leave manual for unit so i cant determine what the diagnostic code is on the board. yellow led flashing rapidly non stop. if anyone could help me i appreicate it. i need to have unit running in morning.model# is fcu060blfr