84 Suburban Heater Issues

[rcbildr]

I've been doing a little work on my brother's 84 3/4 ton 2wd Burb. The heater isn't working quite right and I'm not quite sure what to take apart. The problem I have is when the control is set to defrost, air is still blowing out the vents in the dash and a little is blowing out the defroster vents. It is an AC truck and I'm pretty sure it is getting good vacuum. Where is the part I need to check? I tried searching, but didn't really find anything. Any help will be greatly appreciated. Thanks!

[eaglelox]

probably the cable/wire that changes the direction of the air in the heater/cooler box under the dash

well thats if its anything like mine

[skillet]

Like just stated, the cable/wire would be good to check. I changed out my heater core on my '89 suburban a few weeks ago and I discovered a door inside the HVAC box that had a broken plastic part on it. As a result, the door would not close all the way. My A/C never seemed to get as cool as you would think possible and I remember my dad theorizing one of the doors might be malfunctioning and allowing the A/C air to get 'tempered" from hot air from the heater core. Sure enough, this was exactly what had been happening for a long time. Anyway, instead of buying another piece of plastic from the dealer(bad design), I just bent some flat metal in a hat shape(the exact size of the plastic part) and attached it to the metal door. Now when the door is pushed open or closed, it's metal to metal, instead of metal to plastic. While I was in there, I noticed some of the ductwork didn't seem to line up good(leaving air to escape), so I taped several leaks with an insulation type tape when I reassembled everything. My A/C and heater work better than ever, colder, hotter and with better air flow. I should have taken a picture of the part I made and where it goes, but I have already closed it all up.

[BLE 'BURBAN]

Originally Posted by skillet

Like just stated, the cable/wire would be good to check. I changed out my heater core on my '89 suburban a few weeks ago and I discovered a door inside the HVAC box that had a broken plastic part on it. As a result, the door would not close all the way. My A/C never seemed to get as cool as you would think possible and I remember my dad theorizing one of the doors might be malfunctioning and allowing the A/C air to get 'tempered" from hot air from the heater core. Sure enough, this was exactly what had been happening for a long time. Anyway, instead of buying another piece of plastic from the dealer(bad design), I just bent some flat metal in a hat shape(the exact size of the plastic part) and attached it to the metal door. Now when the door is pushed open or closed, it's metal to metal, instead of metal to plastic. While I was in there, I noticed some of the ductwork didn't seem to line up good(leaving air to escape), so I taped several leaks with an insulation type tape when I reassembled everything. My A/C and heater work better than ever, colder, hotter and with better air flow. I should have taken a picture of the part I made and where it goes, but I have already closed it all up.

Well then I STRONGLY SUGGEST that you git yer happy arse back out there and take pics of it because.....
(Just kidding)

[rcbildr]

Thanks for all the help. A friend of mine was in the process of replacing his heater core (on an 83 Blazer) and I got to take a look at his heater when it was out of the truck. I now have a better idea of what I need to do. Thanks again.

[skillet]

Originally Posted by BLE 'BURBAN

Well then I STRONGLY SUGGEST that you git yer happy arse back out there and take pics of it because.....
(Just kidding)

Yeah, sorry about that. Speaking of arse, taking out those factory nuts and bolts that hold that HVAC box together was a pain in the arse. I got the nuts off, but couldn't get the bolts to back out, due to the factory retaining clips. There's probably an easier way, but I ended up sawing off the bolt heads(firewall side) with a diamond cut-off wheel on a dremel tool. When I put the HVAC box back together I used new nuts and bolts and through bolted the whole assembly(sans clips of any kind) to make it easier to take apart next time. One tip, I strongly recommend taking out the passenger side fender well. It will make access to the firewall side nuts much easier.

[eaglelox]

sometimes if you catch the clip with a screwdriver you can lift it to catch the threads of the screw. i would put a small wedge or screwdriver in and go around to other side. hehehe, to late now.