When installing a 4GXC or 4MXC coil on the new S-Series or Ameristar condensing furnaces you must use an FER coil kit, MAY*FERCOLKITAA, to protect the quality and integrity of the coil’s drain pan. The MAY*FERCOLKITAA kits come with a metal heat shield and are available in each coil cabinet size.
For a list of impacted furnace families and kit numbers, please see the charts in the document linked below.