Ford 2003 Mustang Workshop Manual page 3060

At each function selector switch position, apply 51 kPa (15 in-Hg)
of vacuum and check for vacuum drop.
Does the vacuum drop exceed 3.37 kPa (1 in-Hg) per
minute?
A10 LEAK TEST THE CONTROL ASSEMBLY
Disconnect: Function Selector Switch Vacuum.
Connect a vacuum pump to the function selector switch supply
port and plug the control port that indicated a leak in Step A9.
Select the function selector switch position that indicated a leak
in Step A9 and then apply 51 kPa (15 in-Hg) of vacuum.
Does the vacuum drop exceed 1.68 kPa (0.5 in-Hg) per
minute?
A11 CHECK THE SUPPLY HOSE FOR OBSTRUCTIONS
Disconnect: Mode Selector Switch Supply Hose.
Connect a vacuum pump to the supply hose and try to pull a
vacuum. If the vacuum pump can pull a vacuum, the hose is
plugged. If the vacuum pump pulls a partial vacuum, the hose is
restricted.
Is the hose plugged or restricted?
A12 LEAK TEST THE JUMPER VACUUM HARNESS
Disconnect:
Disconnect the suspect hose.
Plug one end of the suspect hose and attach a vacuum pump to
the other end. Apply 51 kPa (15 in-Hg) of vacuum to the hose.
No
RECONNECT the in-
line vacuum harness
connector. GO to A11 .
Yes
INSTALL a new
function selector
switch. TEST the
system for normal
operation.
No
RECONNECT the
function selector switch
vacuum connector. GO
to A12 .
Yes
INSTALL a new supply
hose. TEST the system
for normal operation.
No
RECONNECT the A/C
damper door switch
supply hose. GO to
A15 .
Yes
REPAIR or INSTALL a
new vacuum jumper
harness. TEST the