I recently flushed out my radiator the other day forgetting to unhook the heater core. some of the rust and loose material washed into the core and it began to leak onto the floor on the passenger side. anyway, i began to take apart the dash and i find myself stuck. I took apart the entire bottom half of dash including radio and all dials for heat , a/c,4x4, headlights etc. I need to take off the frame of the dash in order to get to the top of the heater core box. but don't know how to go about it.

 

It is not an easy job, I have done several and find them easy after doing one, that said here is a link that has all the steps and is the only way to replace one. Buy the way the entire dash has got to come out, sorry.

easy way to change heater core on 1998 s-10 blazer - JustAnswer