Vacuum Leak..continued
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New User
Joined: Nov 2008
Posts: 13
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From: Minnesota
Vacuum Leak..continued
2002 PSD F350 4x4 SuperDuty 4door long box. I am trying to diagnose why my trucks function selector switch to change air flow direction (defrost, floor heat etc
does not work...stuck or default to defrost. Suspect vacuum leak. Checked vacuum motor...it works and produces vacuum to reservior tank. Leak tested reservoir inlet hose even using vacuum pump. Holds a vacuum...so hose does not leak. Checked Reservoir outlet hose and it is not plugged. Connected Vacuum pump to reservior tank (Vac Port) to see if plugged but holds no vacuum. Connected vacuum pump to reservior outlet port and tried to pull a vacuum...no vacuum. I even put put my finger over to vac port but still could not pull a vacuum.. The tank must have a leak somewhere so I should replace the tank, right?
Thanks, Mark.
does not work...stuck or default to defrost. Suspect vacuum leak. Checked vacuum motor...it works and produces vacuum to reservior tank. Leak tested reservoir inlet hose even using vacuum pump. Holds a vacuum...so hose does not leak. Checked Reservoir outlet hose and it is not plugged. Connected Vacuum pump to reservior tank (Vac Port) to see if plugged but holds no vacuum. Connected vacuum pump to reservior outlet port and tried to pull a vacuum...no vacuum. I even put put my finger over to vac port but still could not pull a vacuum.. The tank must have a leak somewhere so I should replace the tank, right?Thanks, Mark.
Logistics Pro
Joined: Jun 2005
Posts: 4,243
Likes: 16
From: AZ
Have you got ESOF (Electronic Shift on the Fly) for the 4x4? If so, check the hoses that connect to the axle ends...they typically split or the o-rings in the hubs go bad and the symptoms you describe sound like that might be the problem. Do a search for ESOF and you will probably find a list of things to check.
