Do i have to remove the dash and steering colum to replace the heater core?

Yes, the instrument panel reinforcement bar, the one running from the driver side across to the passenger side, will have to be removed.
Good luck.

dammm ok make sure you have about 5 hours allowed to do this job.you need to disassemble the under side of dash, both side panels and steering colume panel, remove the colume saddle and let the colume and wheel lay on the seat, all screws across the top of dash and sides
dash must come out , take your time and carefully remove all plugs and gauge attachments, pop the hood un hook your heater lines and either crimp em off or drain and retain coolant now the other bummer,you need to un hook the ac coolant lines you may need a disconnect tool 8 big ones at auto zone now back to the cab remove heater/ac box unscrew the on screw behind the htr core it will slide right out, install new and reverse good luck it isnt to bad
lincolns are even tuffer lol

No you do not have to drop the steering column to change the heater core. It should be located under the passenger side of the dashboard. The easiest way to find where it is located would be to look under the hood for two hoses that go from the front of the engine through the firewall and that will tell you exactly where it is located. To replace the heater core you will have to disconnect the two hoses under the hood from the heater core then remove the heater box from underneath the dashboard.

major job, you will need to pull the dash out of the way, disconnect wiring under dash steering colum out of the way, the outside right inner fenderwell needs to come out to get access to a stud, remove nuts from studs holding heater core case, remove inside screw holding top and bottom of heater case, remove heater core, big big job,

If you smell antifreeze it may be 3 possibilities: 1. you may have a leaking hose/hose connector , or water pump. 2. your heater core is bad and needs replaced. Unless you know what you are doing I would highly suggest taking to dealer for heater core replacement. The dash and steering colum has to be removed to get to the heater core. This is not an easy job believe me (about-900-1200 job). If you have your heater core replaced then also replace the climate control door. This is good preventative maintenance and also a a dollar saver. I would have a pressure check run on your radiator as a first thought. All you may have is a bad hose and that can easily be replaced.

First disconnect steering knucke under dash. Remove dash assembly to reveal heater/AC case. Disconnect heater hoses from engine compartment. Discharge and capture AC refrigerant. Remove heater case ,replace heater core . re-assemble .

big job maybe you should buy a manual for that blazer, also label everything, the steering colum and every thing has to be removed before dash can be removed, good luck.

To replace the heater core in that model truck you will need to remove the whole dash, steering colum. Then discharge the A/C and remove the heater/a/c case. It is a time consuming job and difficult without the proper tools and info. If you are going to attempt this then be sure to disable the air bag system by disconnecting the battery for at least 10 min. before you start working. Good Luck

yup you will have to remove the whole dash, unhook batteries and wait 20 min, for air bags, unhook all wires ect from steering colum and remove the colum as an assy, behind the kick panels both sides you should see some bolts holding the dash to the kick panel (some will have a sloted holes so you dont have to remove the bolts just loosen them (this allows you to tilt the dash back away from the winshield) unhook all nessesary wiring, heater controls, stereo wires ect.. remove screw's securing the upper dash to firewall, tilt dash back and check for any other wiring ect.. remove intire dash! now you will need to remove the intire heater box to gain access to the heater core, you can pinch off the heater hose's so you wont have to drain the intire cooling system, some of the vans used a quick disconect right at the firewall and require a special release tool to release them almost impossible without the tool, once this is done you have to evacuate the ac system and unhook the lines, then you can remove the heater box( nuts on the firewall engine side) and dissasemble to gain access the the heatercore! (not for the faint at heart) some models can take as long as 16 hrs to r&r so if your asking about doing one means your not going to have fun! I recomend taking it to the shop and have it done by pro's, or at least spend the money and buy a repair manual
make shure you do it in a heated shop cuase if you fight it in the cold your apt to break some plastic! take your time and dont get frustrated, it will pay off, and always vacum test the new core before installing it to make dang shure it doesent leak before you install it! reasemble in the reverse order, this is just off the top of my head but gives you a general idea what your up against! have fun!

Just pull the dash back a little by undoing all the bolts and screws, its going to be a tight fit find someone with small hands.