Service Letter: New Defrost Board not Interchangeable

Service Letter: ST-001-16

SUBJECT: LX Series Package Heat Pumps and Split System Heat Pumps

Defrost Control Boards

• The new LX series package and split system heat pumps use a visually identical defrost control board. The purpose of this ST letter is to make the field aware that although they look identical, they do have different defrost curves programed in them and are not interchangeable.
• The boards appear identical; however, in the black box in the top right quadrant of the control a three digit number is present that is used as an identifier.

 The "162" is used on LX series package heat pumps

 The "009" is used on LX series split heat pumps