It has 1 big hub bearing per side and you can not service them. It has factory sealed bearings. If there bad then you must replace the bearing.
Call your local auto parts store. Front wheel bearings can go from $50 to $200 (plus labor) depending on manufacture.
2 wheel drive, yes. 4 wheel drive, no.
Replacing a wheel bearing in your Chevrolet blazer will cost approximately $175 per bearing. You can save $125 by doing the work yourself.
You need to check all 4 wheel bearings. REPLACE AS NEEDED
How to Remove the Steering wheel From a Chevy Blazer 2001
How do you change the wheel bearings on a Chevrolet aveo 2005
In most cases wheel bearings cannot be repaired and must be replaced. Remove the tire and wheel. Remove the axle end cap. Remove the wheel bearing seal. Remove the wheel bearings. Reverse the process to install the new wheel bearings.
Instructions on how to change the rear hub wheel bearings on a 1996 Chevy cavalier
It depends what year they are and if they are 2 wheel drive or 4 wheel drive.
2 wheel drive
A 1996 Chevy Blazer Does have a transfer case IF it is equipped with 4 wheel drive
you probably need to repalce one of the front wheel bearings(hub assembly). the sensor for the abs is located in the assembly