How do you remove heater core from 1986 Chevy blazer?

Answer 1

I have a 1991 GMC S-15 Jimmy, which is the GMC equivalent of the S-10 Blazer. The Chilton manual may help locate the core, but is useless for the actual work. Under the dash on the passenger side is two cover panels. Remove these panels and you will immediately see the heater core. Next, remove the cover panel for the radio and central vents, then remove the stereo. Behind the stereo you will seen the top half of the left side retaining clamp for the heater core. It is held in with a screw. Open the glove box, and at the back is a small access panel that is held in with a screw. Remove the panel and you will reveal the final upper half of the right side retaining clamp. It also is held in with a screw. Before you remove any of the four screws for the retaining clamps, remove your heater lines in the engine compartment. Be prepared to replace the return line as it connects to the engine block with a copper line. Cut the rubber part of that line about halfway and buy a heater hose coupling to connect a new heater hose to the old one. The heater lines will not slide off the heater core as they will be sufficiently melted to it. Take a knife and cut the old hoses length wise on at least two sides and then peel the old hoses off like banana peels. Now remove the heater core retaining clamps and pull the core out. The newer cores tend to have much longer copper lines and are spread further apart than the OEM. This means it will not fit through the hole in the firewall. VERY CAREFULLY bend the new copper lines closer together until they fit through the firewall. Be careful not to break the soldering at the base of the copper line. Installation of the heater core is reverse of the removal. It took me nine hours because the Chilton manual simply stated to remove a cover panel and then remove the core. I had to figure it out myself, and of course the first replacement core broke when bending the copper lines. Make sure you keep your receipt in case this happens!