Carrier 438MG series Installation Instructions Manual page 16

The incline of the drain hose should be
2.95in / 75 mm or less so that the drain socket
does not have to withstand additional force.
pipes as shown in the figure below. Select
Unit: in/mm
When the electric wiring work is finished, check
the drainage flow during the COOL operation.
Unit: in/mm
16
Keep in mind that if water collects in the
drain pipe, the pipe may become blocked.
Unit: in/mm