Hi i have a 98 blazer no 4x4 i have replaced the actuator and the 4x4 light switch on the transfer case i have no suction at all shouldnt i have suction at the switch on the t case ?

 

It would be easier to help if you added punctuation.

That aside... Does your Blazer have the 3-button 4wd selector switch or the 4-button? I'm guessing from what you wrote it is the 3-button one for which there are vacuum lines that go to the transfer case. To answer your question, yes, I believe there should be vacuum supplied through those hoses. I'm not an expert on that particular system so I cannot tell you which ones should have vacuum and when. (In my .sig file below, there is a link to a thread for replacing the vacuum hoses on a 4-button/Auto 4wd system)

Know that the hoses that supply vacuum to the 4wd system also supply vacuum for the HVAC system actuators. It is not uncommon for issues with the 4wd system to show up with problems with the HVAC system not directing air to the correct vents.

When operating properly there will also be vacuum supplied to a diaphragm located under the battery tray that pulls on a cable that engages the front axle. Even if the transfer case is working properly and is engaged, if the front axle is not engaged, then one of the front wheels will be free-wheeling and no torque will be passed through the axle from the transfer case to the front wheels. This hose to the diaphragm or the diaphragm itself can be leaking resulting in no drive at the front wheels.

In short, check that all of the vacuum lines are connected and that the diaphragm is not damaged.

 

I had a 98 with the same problem... First I would simply replace the #15 10 amp fuse located on the dash, driver side where the door is... If no luck try replacing the 4x4 push button switch on your dash... I hope this might help.

 

check if you have vacuum from the ball canister inside the drivers fender , the line runs from the canister into the vacuum system for hvac and 4x4, there should be a T where engine vacuum and the canister come together and go to the Tcase switch.