A/C Vacuum Check Valve
Connect the A/C vacuum check valve to a vacuum pump with two hoses and a tee fitting.
Apply 51 kPa (15 in-Hg) vacuum on the A/C vacuum check valve and observe the gauge reading.
If the vacuum loss exceeds 3.37 kPa (1 in-Hg) per minute, remove the A/C vacuum check valve from the pump
and plug the vacuum hoses. Apply 51 kPa (15 in-Hg) of vacuum with the pump to be certain hoses and tester are
not the cause of the leak.
Does the A/C vacuum check valve lose more than 3.37 kPa (1 in-Hg) of vacuum in one minute?
Yes
REPLACE the A/C vacuum check valve. TEST the system for normal operation.
No
RECONNECT the A/C vacuum check valve. GO to
A7
.
A7
CHECK THE VACUUM RESERVOIR
A/C Vacuum Reservoir Tank
Use a vacuum pump to leak test the A/C vacuum reservoir tank.
Does the reservoir leak?
Yes
REPLACE the A/C vacuum reservoir tank. TEST the system for normal operation.
No
RECONNECT the A/C vacuum reservoir tank. GO to
A8
.
A8
CHECK THE SUPPLY HOSE
Function Selector Switch Supply Hose
Use a vacuum pump to leak test the function selector switch supply hose.
Does the function selector switch supply hose leak?
Yes
REPAIR or REPLACE the function selector switch supply hose. TEST the system for normal operation.
Page 6 of 30
1999 F-150/250 Workshop Manual
8/16/2010
http://www.fordtechservice.dealerconnection.com/pubs/con...
