You will have to remove the entire dash assembly and the heater box assembly. Then you have to disassemble the heater box to get to the core. Labor guides list it at around 7 to 8 hours labor.
February, 29, 2008 AT 7:25 AM
I have a 2001 Blazer and the heater core started leaking on it last summer. On page 18 of this Blazer forum is a question titled " Accessing the heater core on a 1998 Blazer". That caught my attention since I needed to replace mine. Thanks to the technician I got all the info I needed to do the replacement. I posted some pictures to give you an idea of what you'll be looking at if you do it yourself. It's NOT a project I'd suggest getting into unless you have the time, tools and patients to complete. Something I learned the hard way, three weeks after I replaced the heater core it would only blow out hot air. There's a little gizmo called the blend door actuator that makes the air blow over the A/C evaporator coil or the heater core, or both. Mine died and guess what? You have to pull the dash to get to it too! If/when you have this done have them replace the actuator. They're not expensive and could save you several hundred dollars by not having to pull the dash again just to replace it.
February, 29, 2008 AT 8:54 PM
You are correct. This is not a job for the beginner. It's a full day of hard labor to change a $25 part.