I cant figure out where my vacume line hooks up at. Its under the hood, drivers side in the rear corner. There is a t splitter where the vac lines hook up and the one i cant figure out where it GOES TO FROM the middle of the splitter. When i plug the air line the 4wd drive works fine, but when unblocked it will not work. Does anyone know where this hooks up to. My vehicle is a 1999 chevy s-10 zr2, automatic with push button 4wd. The air line is only about 6 inches long and does not look like it broke off just slipped off of somewhere.

Should have one under the hood somewhere . On the strut tower , radiator core support , on the under side of the hood !

If you are talking about the 4x4 make sure the vacume hose to the actuater and the vacume switch on the trany is working properly it is located on the drivers side of the transfercase on the top with three vac lines comming from it.

Most GM cars have a vacum routing diagram on the under side of the hood if not the library may have a repaire manuel you could look at and get copys

you dont have any vacume at the ball resivore under the hood.. some are located on the hood its self and some under inner fender.. look for a black plastic ball lookin thing with 2 vac lines running to it.. one should be all rubber and one should be plastic with rubber ends.. the all rubber one is the in line follow it back to the engine and see if it is damaged somewhere, if so repair or replace.. one other place i have found problems is under the dash by the dog house or just above the dog house in the center.. improper installation of the house will kink or pinch the vac line and you will not get any vac at the control head

3 way splitter in the upper left hand conner under the hood. Should be under or near the silver canister.It is the vacum for youA/C and runs down to the drivers side of the motor to a vaum moduel.

The vent doors are vacuum controlled and will default to defrost when there is no vacuum. Check for vac leaks under the hood. Check the lines to the vac ball mounted to the hood in the driver rear corner of the engine compartment near the brake booster.

Any time your dealing with a 4x4 system the best start is at you front axle. Its primarily a vacuum leak so check to see if the 2 vac lines are hooked up (its good to check the electric connections.). When your 4 wheel drive is engaged and the motors running you should have vacuum at one or both of thee lines depending on if your in 4 hi or low .
If no vacuum at axle check the Vacum switchs(the plug with 4 vac lines) on top of the transfer case it will have 2 feed lines(grey & green) they conect in to the into the vacum harness on back of motor (passanger side). A vacum schematic is normally located on the raditor core support (right under the hood next to hood release)
Hope this helps

check vacum lines to the hub's
and the switch under hood (drivers side finder well ) two vacum lines one electric plug

Does your control panel have cables working some of the doors below in duct work. Can you see any cables up under passenger side or drivers side. Those lines I think your talking about, will only get vacuum as needed to move an actuator(vacuum motor) , so I'm guessing that if the control isn't in the right position, then it won't route vacuum to that particular line. I have msn , but I never set up an account, it's just used by my kids, sorry. I always figured I type too slow to have a conversation on there, but maybe I'll consider it soon.

You more than likely have a vacume hose that has come off at the vent switch or under the hood. Unfortunatly you will have to pull the vet switch out of the dash to see if there are any vac. lines off. You can visibly inspect the rubber and plastic vacume lines under the hood. Just be careful how you handle the plastic lines as they become brittle from the heat under the hood after a period of time.