Trane TCONT900AC43UA - FREQUENTLY ASKED QUESTIONS AND ANSWERS

HP - B 1
Control Boards
20 SEER Heat Pump Model Control Boards...................................................................................... 2
Overview ......................................................................................................................................... 2
Sump Heater Control ...................................................................................................................... 2
Sump heater operation at power up ........................................................................................2
High Pressure Monitor Logic ............................................................................................................. 3
Low Pressure Monitor Logic .............................................................................................................. 3
Cool Mode LPCO Logic...................................................................................................................... 4
Low Temp Lockout in Cool Mode ..................................................................................................... 4
Timing Logic for LPCO Open Events ................................................................................................ 4
Sensor and Control Voltage Fault Detection ..................................................................................... 5
Power Interruption Protection ............................................................................................................ 6
Oil Return Mode 20 Seer Heat Pump Models .................................................................................... 6
Ambient Temperature Sensor and Oil Return Mode ........................................................................ 6
Charge Assist Feature All Models ...................................................................................................... 7
Demand Defrost Cycle Heat Pump Models ........................................................................................ 7
Defrost Component Electrical Wiring .............................................................................................. 7
First Defrost Event.......................................................................................................................... 8
Terminate Temps ............................................................................................................................ 8
Diagnostic LED .............................................................................................................................. 8
Demand Defrost Control Checkout.................................................................................................. 9
Board Variations ................................................................................................................................. 9
Communicating Air Conditioning and Heat Pump Systems
Section B