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Hi everyone, about a month ago my truck started only blowing air out of the defrost, vents or floor doesn't work. I read that it is probably a vacuum problem, so I checked the pump by taking a hose off and feelingfor suction. I felt it on the 2 hoses I checked(ontop of the passenger side front fender). My 4x4 also worksso does this mean its not a vacuum problem or can there still be a leak furth down the system?
Does anyone know where else I should look? I read there is something behind the glove box.
So there is a hose going from the vacuum pump to a black box right in front of the pump. That hose has good suction but the other hose, a gray one, that comes out right beside the other one has no suction. What is this black box, and do u think its broken, or mabye there is a fuse or relay that's bad. Any help will be appriciated
The big oval shaped box next to the vac pump is just a resevoir tank. Those don't cause much problem. Next to that tank, on the fender wall just below the hood sill is a small vacuum solenoid valve. When that valve starts to fail it leaks all the vacuum when actuated. It is easy to change. You also want to check all your hoses down to the locking hubs. I know you think your 4WD is working, but there is a good chance that it is not working correctly all the time.
You could have a vacuum leak under the dash, but my money is on the 4WD system.
The hub module can be seen in this pic. It is the cream colored box, and the hood spring shock is pointing straight toward it.