Heater Box

[oltronj]

I have a 1990 GMC suburban with a/c that the heater is giving me problems. It always is blowing out of the vents, I have vacuum to everything that I can find to test. Is there a way to get to the vacuum actuator that is on the back of the box by the firewall? Or at least a way to look inside there and see if it is even trying to move? The other question is does anyone have some advice on pulling the whole box out, I have used the search tool here and have found all kinds of pictures of ones that are already out but not much for advice on actually pulling it out.

[68Timber]

I need to rebuild mine as well and have been meaning to do a search and see if there's a good write up. Let me see what I can find.

[oltronj]

I don't know the rules for posting links to other sites but I found a great write up on another site with lots of pics and some pages out of a service manual with a troubleshooting guide.

[krazy_texan]

OK here it is boys I just pulled mine and its not overly bad. First disconnect your heater hoses. Then remove your glove box. After that there is one bolt under the dash to the far right side this bolt is also holding a wire securement loop. Next underneath your hood all of the studs that are around the a/c box on the fire wall you should need a 7/16 deep socket and a swivel and an extension only one is on top and the other 2 are on bottom one being almost under the blower motor being a major pia once you have practiced contorsionism and removed all the nuts outside the fire will pull the a/c box out just enough because on the top stud there is likely a push nut to help hold the box in place. Inside the truck to the left of the glovebox is the section of duct that goes up to your dash vents there are 3 screws that hold this in. Get that removed and your heater box should remove fairly easily. I am going to remove mine again tomorrow I'll take pictures of the whole ordeal and disassembly of the box for a new heater core.

[68Timber]

I'm looking forward to seeing your how-to. Mine is ready to be pulled, weather permitting...

[krazy_texan]

Been running into some issues the vacuum to close my door to shut off the vents is not working properly I'm currently working out bugs and getting increasingly frustrated

[jetmech85]

I pulled mine two weeks ago. Like krazy texan said it wasn't too bad. It was getting to the heater core itself that caused me grief(mine was leaking). I still haven't got the thing back together. I would like to see a write up on repair/rebuild the heater box, blend doors and heater core.

[68Timber]

There's one or two well known points of failure on them but I don't recall what they are. I'm sure there's a good write-up already here somewhere. I just haven't made time to search for it.