My heater core (87 K-5 Blazer, 350 ) started to leak and has gotten worse so I picked up a replacement. For the life of me I can't see how to get to it. There does not seem to be any bolts to remove the plastic housing inside the cab. It has air conditioning which on the fire wall seems to be where the evaporator is mounted. My Clymers repair manual is usless. Any one replace one of these?

 

Remove lower dash cover, Remove radio, Remove glove box door, Remove rear panel in the back of the glove box. With the radio removed reach on top of the heater core box and remove the flexible vent tube from the top of the heater core box. A little twist and pull and it will come out. There are about 6 or 8 screws around the front of the heater core box. You need to remove the front cover. Some you can get to from under the dash. The top ones from the opening in the back of the glove box or through the radio opening. Once all the screws are out you can remove the front cover from under the dash. The heater core will be right there secured with two straps on each side. Remove the lower bolts and loosen the top bolts. With the heater hoses removed from the core it should pull out. It takes a little twisting and turning. Hard part is getting the new core in through the firewall without damaging the solder joints of the heater core pipes. As it is a tight fit to twist and turn the heater core through the firewall and getting it in the right position. Some people have loosened the dash mounting to give a little extra room. I have done mine 3 times in 420K miles. Good luck and hope this helps.

 

I saw some where a suggestion that if GM made a access panel in the blower/heater core panel it would make it easier to change out the heater core. Has any one tried cutting an access panel out and making a cover? good or bad idea?

 

You still would not be able to get to the heater core as it is on the inside of the firewall and is secured by the two straps. Bad Idea

Just be glad you do not have a 2nd generation blazer as the whole dash has to be removed. I have an 89 and a 2000 and I hope that the 2000 Jimmy never starts to leak.

 

Thanks