Goodman GMVM Service Instructions Manual page 70

SERVICING
MODULATING FURNACE PNEUMATIC TUBING DIAGRAM
Low & High Pressure Switch Assembly
Front Cover
with "H" Fitting
Pressure Switch
Black Tee
MUST
be left open
Modulating
Gas Valve
+ Port is Open
Negative (-)
to the Atmosphere
Port on Gas Valve
Upflow Model Shown
For representation only. Actual unit may vary in appearance.
70