2000 Heater Core Replacement Summary - DISCUSSION THREAD
 

Well, I went and pulled the dash out and replaced the heater core. What I hoped would be a 5 hour job turned into a 17 hour marathon of screws harnesses and vinyl.

I did learn quite a few things while the dash was out and these things may or may not help anyone looking to do the dreaded heater core replacement on their blazers.

I do feel that I need to warn you. There is a good chance that your blazer may be a bit more different than the blazers mentioned in this forum or elsewhere as I have learned, the more options are in the blazer the more harnesses/panels/obstacles you may have to contend with when your pulling the dash out.

I had auto climate on mine and that may or may not make a difference. I have a 2000 blazer LT with tape deck in center console. I could not for the life of me figure out how to take out the damned thing and opted to work without taking it out. I did not remove the seats.

I also did not have to drop the steering column as others have suggested though there were some brackets with four 10 mm bolts connected the dash to the chassis under the steering column that need to be taken out as well as the 2 10 mm bolts under the dash behind the panels: one on each side of the dash assembly (one is accessed behind the glove box on right side). There are also a few 7mm screws to remove on the dash under the speaker panels and defroster panel.

I removed my radio and ac/heat control unit to give more room to reach into the dash and survey things. You may not have to do that. Some have taken the dash out and disconnected it then. I also disconnected the odometer/instrument panel as the dash will come out easier over the steering wheel.

The panels at the bottom aren't too tough to pull out. Just keep checking for screws way back there under the dash if you feel you have them all and it still isn't coming off. You will have alot of panel screws. I kept the screws for each panel with that panel so as to keep track.

Once the dash is loose, you can start looking to see what electrical harnesses you have to remove. The main harness under the blower motor vent behind the glove compartment was disconnected by loosening the 7 mm nut and pulling the 2 blue locking keys out and then wiggling it free. You may also have to unscrew the fuse connected on the driver side as well as the computer OBD-2 connector on one of the panels under the steering wheel.

With everything disconnected, you should be able to pull the dash out. Keep an eye on the driver side as the dash may take out your hazard switch as it swings free of the railing (ask how I know).

Now, some have said that there are 2 10mm bolts to remove behind the passenger side fender and recommend dropping the fendor just enough to get to it. Looking back, I couldn't see a reason to and in hindsight I may have wasted time doing that.

If the heater assembly won't come out and everything else is loose feel free to do that.

Instead, Try to just get the 2 screws on the engine side firewall by the heater core connector (one on the right and one on the left/bottom area besides the evaporator cover) as well as the bolt in the evaporator by cutting and using a ratchet wrench. Keep in mind that there is also another 10mm bolt on the cabin side of the firewall under the heater assembly that needs to come out.

Now here is the part I couldn't find info on and had to wing it. There are two tabs - one on each side of the 10 mm bolt cabin-side firewall under the heater assembly. It seems the bolts can be wrenched loose on the engine side of the fire wall....I never found them. Instead, I tore those bastards loose. Don't do what I did. Use a dremel as you may have a hell of a time getting the heater assembly back in line to get the bolts back in and torn tabs make it all the more harder.

That happened to me and must have added a good 2 more hours trying different ways to get that damned bolt to thread cause the tabs were in the way and would seat right as would a strait rotory cut would have.

With everything loose you should be able to pull out the heater assembly by disconnecting a few choice vacuum lines and some more connectors. The cooling line connectors on the new heater core will have some play so you can get it in there correctly. Make sure that you hook the two vent looking connectors going into the carpet before thinking the heater assembly is working your nerves. For some reason the heater assembly connects to the floor vents which in turn connect to mounts under the carpet.

Now just reverse what you did. Some things to keep in mind.

-The rear wiper/gate open switch wire can and will get caught when you put the dash back in. Keep it loose.

-There is a connector for the actuator motor on top the heater assembly against the firewall. Connect that before you bolt in the dash. I had small fingers and finagled it in by luck and prayer.

-Make sure you connect your courtesy lights for floor lighting back to the panels you took them off of.

-Your passenger side door sensor may or may not have a wire. Try to see if it does before you get started so you don't worry about it and take the dash apart again trying to find it before giving up wondering if it even existed.

-You will need a friend to help put that heater assembly back on the firewall to get all the bolts to thread. You will also need some dexterity to put that one bolt in the evaporator housing back in.

When you have everything back together again hook up your cooler lines to the heater core and open up the radiator cap/reservoir cap. Turn on the engine and make sure you get all the air out of your cooling lines.

The automatic Climate control may need to relearn temp parameters or at least it seemed to the first few drive cycles.

Remember, this was for a 2000 blazer LT 2WD with all sorts of options installed. It may differ just a little from your setup or it may be completely different. Either way I hope all this info I learned and have transferred to this post will help any who doesn't want to pay money to get it done.

Unfortunately, I didn't take any pics. I seriously think I invented a few more cuss words over the course of the repair, But it feels good to have heat for the cold season as well as pride in having no screws left when it was finished! :)

EDIT: Make sure when you put the dash back on that there are no cloth/felt flaps covering the metal screw catch assemblies that the dash needs to screw in at the defroster vent and speakers. You may inadvertently try to screw and nothing will catch or you will thread in the bottom part of the attachment part. I thought I had it and had to pull the dash out again to fix it as everything was rattling.

You've had much better luck than myself. I replaced the heater core on a 1999 Blazer, now nothing works. No heat/ac, no winshield wipers, no dash gauges, and a few more problems. I undid the screws from the evap cover and the one on the firewall, pulled it away and pulled the core out (after dash disassembly). Put new core in, conntected hoses in engine compartment.
The only wired connections I found was the main harness on the passenger side. I didn't pull the blue tabs, just pried it apart after unscrewing the nut. I believe there was another connection behind the headlight selector on the drivers side.
I'm desperate for help as my Blazer is in pieces and doesn't function correctly.

I can't say for sure as each vehicle may be different. It does sound like you need to check the vacuum lines behind the dash going into the heater assembly. They look like electrical wires but you can squeeze them. Make sure you check all lines as one may be loose and that would keep the vents from moving to change air flow. Make sure your A/C control unit is hooked back up as well. It may not be connected fully.

I am not too keen on the electrical issues though. I would follow the guidelines given in your original post regarding those issues. Take a close look at all connectors and double check any crossed wires. Make sure your grounds are good as well.

Electrical issues require persistence more than anything. You really have to be methodical in your troubleshooting. Make sure you have all your harnesses connected. Some can hide on you once the dash is put back in.

EDIT: NVM I found some images regarding the repair.

Thank you for the narrative.....I'll be attempting this on my 99 Bravada real soon. It's currently bypassed, but the weather is getting colder. Will post some results shortly thereafter. Or maybe I'll just get rid of the thing. It needs a new windshield and tires anyway.

I did my 2000 LS last year. Man, the 2 bolts down the bottom were a pig to find. i didn't realize how much of a contortionist you could be to get to them. And I work on C130's which have bolts in stupid positions. They attach to 2 brackets that hold a heat shield on that deflects exhaust heat away from the air con unit. I fitted a new one as it had dissappeared. the dealer had never seen one before and wondered if my find would cure a few air con problems they had with other customers cars. I used the write up from the Haynes manual as well as various posts. Nothing was exactly the same. I didn't get heat first thing. i found I had left a cable off obviously in an awkward position.

I'm afraid to do mine, lol. Too much to possibly go wrong. I'll either attempt it, or chicken out, and pay someone to do it, lol.

In the middle of it right now. Taking a coffee break. I appreciated your comments; I am using, or rather NOT using, the Haynes manual I have, since nearly the entire dash removal is for vehicles older than mine, a 2001 2wd LT. I have the auto climate control as well. I have the speedo, climate control, panels, bezel, radio and a dozen bolts out of the dash so far. I'm taking pictures like a maniac, labelling everything, and recording notes of the steps I've taken. Wish me luck!

Well, it's all out except those two firewall bolts hidden away. I was wanting to do it "right" by pulling the fender well and whatever else I had to do to get to it, but at this point, I'm getting the dremel.

The only major issue I ran into was the wiring to the cassette. I couldn't figure out how to get it out either, so I couldn't unplug the wiring at the cassette. I ended up weaving the three wiring harness sockets on the other end of the cassette cable through the dash and left them all in the Blazer.

When I yanked the main harness behind the glove box, I pulled those blue plastic deals off, but I'm wondering if I needed to. After unplugging it, I couldn't see what difference it made with the blue "combs" out.

I didn't drop my steering column (but of course did lower the tilt function) but I think if I had a good wheel, I would in the future. The black rubber skin is already coming off on top, but if it was a nice wheel, I wouldn't have risked it.

I have taken tons of pictures and written my notes as I went. I did find there were bolts I didn't need to take off behind the instrument cluster, radio and climate control module.

The absolute worst part of this so far has been the bolt inside the heater box. I cut out the service opening on top, and unbolted the plate underneath the skin. There was a filter screen in there to the left which was sitting on top of the washer that comes off with the bolt. It was hard enough getting the socket into that little hole (eventually I just took a deep socket off, scraped my hand into the hole, and unscrewed it manually) but ever turn it got harder because the washer was compressing the filter. Ugh.

I think I'm quitting for the night. I was hoping to get the core out as my quitting point, but I figure I'm more than halfway.

I have 6 hours into it, taking tons of pictures and labeling everything, and I've never done it before.

Just started trying to get the dash out today. Have a 2001 LT with climate control as well. No book, can't find it, not going to buy another one. The heater core has been messed up for some time and I already knew it was going to be a several day project so I waited till now to even try and start this. I have the week off and hope to get the new core in and everything back together by Christmas. That's the plan anyways.

So for the info from this thread has been helpful. Adam, I am really wanting to see how your 2001 comes out since you have the same type of Blazer. Probably should take a few pictures myself.

I think when my heater core starts to leak in my 2000 I will bite the bullet and pay the dealer to do it. I am usually not afraid of big jobs but this scares the hell out of me. So many things that could go wrong. I like everything to work as intended. I have done the heater core in my 89 Jimmy but that is a piece of cake compared to what is involved with the 2nd gens. If I can't afford it I will connect the two hoses together untill I can.

Got it out yesterday. What a pain in the rear that was. Didn't expect the wiring harness that goes under the middle consol. Not sure what that box does but it has wires that have to come off in order to pull the dash so I had to push the dash back up in place, put one screw in to hold it there, and remove the consol in order to disconnect the mystery box.

I have decided that every square inch of this vehicle has at least one wire running through it. Never have I seen such a mess of wiring on a vehicle before and it makes me really appreciate my old truck. Next Blazer I buy will have to be built in the 70's or 80's.

All that aside, hoping to get the core in today and hopefully if it doesn't start raining will get the dash back together. Be nice to have this turn into a two day project rather than spending the whole week on it.

Please post the pictures you have when you finish. That's the one thing I didn't do and wish that I did. It will be really great to supplement all the info in this thread with some nice pics. Particularly of the two bolts that everyone seems to have a problem with. as well as the harness with the blue forks "out".

THIS IS NUTS!!!!! One of the bolts that has to be removed in order to take out the plumbing/air ducts/whatever is located behind the AC coil. After searching for about an hour for what bolt was still holding this thing on I finally found it. Had to chop out part of the plastic cover to get to an access hole. If memory serves, this is the place that some models have a resistor or something. Anyways the plastic cover is dry rotted so it crumbled while trying to cut the access. Guess I will have to try and fix that when I go to put this thing back together.

After gaining access I see that my last bolt is located down in a hole that my hand or a wrench can fit in and the bolt itself is up against the AC coil. So even if I could get a wrench to it I would put a hole in the coil when the bolt begins to back out. SOOOOO It would appear I need to remove the AC! I am really beginning to HATE this vehicle.

Well back to work. Had to just take a break and try and cool down a bit after seeing this mess.

Definitely success, and anyone with a second gen, this actually was way easier than I expected. Don't worry about the book. I had the Haynes open and it really did nothing for me. This list got me through.

The job was time consuming, and there was one bolt I couldn't find on any suggestions but ended up being there ( right behind the distributor, it's the one that holds the corner of the heater box in the engine compartment.) I spent 30 minutes trying to get the floor heater channels out thinking that was what was holding me up. Nope, another bolt.

I will try to post pictures tonight. I have basically written a complete how-to for my 2001 with auto climate, with bolt sizes and pictures for pretty much the entire removal job. I spent 7 hours getting to the core, about 30 minutes transferring the foam to the new one and cleaning the box (make sure you clean it good!) and about 4.5 putting it all back together. 30 minutes of that was because I dropped the socket in the heater box. I had to have my wife come get it with her smaller arms.

If you have any immediate questions, post here or email me personally. I have most of it fresh in my mind.

Incidentally, two things that need attention: my push-button for the rear hatch isn't working now. It does outside in back, but not at the dash. Strange about this? It is one unit with the rear wiper which DOES work, and it's one harness. Maybe a fuse; but my wife has been driving it since I finished. Also, the drivers door plunger isn't working. The cabin lights do not come on when I open the door, and the radio does not turn off when I've reached my destination. Interesting part: I didn't touch the wiring for it; it came out with the dash. So maybe I disconnected it accidentally when installing the parking brake cable.

Now, the bolt in the, well, I call it heater box, but the one you have to cut into. That sucked, but I got it out. Here's what I did. First the ruibberized cover on mine, you cut it out, and then underneath there is an access panel. 3 5.5mm (I think) little bolts and out it comes. Inside, there is what I thought was a filter, not a coil. It was relatively movable. At any rate, the washer of the bolt inside there was under it a bit. I took a deep socket and a 3/8" wrench to the bolt in there. 10mm if I remember correctly. I could get one click on the ratchet, so I just took a deep breath and slowly started the bolt with a single click each throw (the handle of the ratchet had only that much room in the hole of the box.) After it started to get loose, I took the ratchet off and reached my hand into the hole. I'm 5'11" and 200 lbs, so you can get my size. I have a couple of cuts on my hand from this weekend, but I got my hand in, and wound that bolt out with just the socket. Surprisingly, I got it back in within an acceptable time frame, but when done, I accidentally dropped the socket trying to get my hand back out of the hole, and had my wife come in to retrieve it.

That box on the lower front with the three connections (behind the ash tray), yes, I took that one out after the fact, just like you. Never read anything about it, but it's important I suppose (though surprisingly light given the three major harnesses feeding into it.) By the way, the umbilical cord that runs into the center console? That's for the cassette on mine.

I find that it was easiest to get that bolt out with a long ratchet box wrench.

If there is anything you guys would want for Christmas, I Highly recommend crying for a ratchet wrench set. Best invention since the origional ratchet set.

I know my father-in-law is getting a set, from my wife. Hey! Over here! (Waving hand) I want one!

I do know this: I tried the small socket on the ratchet, and it wouldn't clear the filter/screen/whatever. It was just too close. The deep socket allowed the ratchet to get away from the screen far enough to function.

I am done. The bolt that appeared to be on a AC coil turned out to be some kind of mesh that is very flexable. Still could only turn a rachet about a 1/8 turn at a time. Took some time but did come out. Thought I had all bolts removed but found two more coming in from the engine side of the firewall. Never could see them on that side but could see that there was what appeared to be two brass bolts going into the box. Well by this time I was tired of messing around with the thing so I hunted like crazy and finally found my book. What a waste of time. The book was absolutely no help.

From what I have found on the internet and in my book it would appear that every year has a different way of mounting this thing and from this thread it makes me wonder if there are differences from vehicle to vehicle based on maybe options, engine size, etc. Nothing I have found matched up with what I found on mine.

Anyways, as I said I was getting pretty fed up with this thing and figured whatever the two bolts was holding on the engine side would be fine if I cut the plastic free from them. Out come my dremel and in a matter of about 1 minute the air box was free.

My foam on the heater core was pretty well rotted so I went with no foam. Figured I may sell this Blazer before long. It has been nothing but trouble lately and it is such a pain to work on. It makes me have nightmares about wiring. So far I have not found any part of this vehicle that doesn't have a wire running to it or through it.

In the end it is back together. Have several left over bolts including that annoyance in the AC hole. Yep didn't put it back in. Hands to big to fit in the hole and I wasn't about to spend another minute messing about with it. Got three mounting bolts on the box and it felt secure to me so the dash went back on. Tested it out and I have heat without any antifreeze smell and all my electronics appear to be working so overall I am very satisfied.

I'm glad you got it all back in! Enjoy the heat!

2001 LT Auto 2wd with climate control
 

Figured I'd post my notes for any others attempting this one on this year.

EDIT: High resolution pictures on this album http://s149.photobucket.com/albums/s55/thenewvintagehome/2001%20Chevrolet%20Blazer%20LT%20heater%20core/ Make sure you click on them to get the description at the bottom. Click again to get the high resolution. Sorry! They're not in order, but are labeled by the number on this list. This isn't necessarily the best order, and you'll notice in the pictures that I realized going through it that I should do things differently. Hope this helps you all!

1. Battery off - don't need airbags going off in your face!
2. Lift passenger door threshhold out, pull out kick panel
3. Remove two 7mm bolts holding passenger lower panel
4. Remove 4 7mm bolts for middle panel with 12v accessory receptacles
5. Disconnect harness from middle panel (not at the receptacles)
6. Remove two 7mm bolts from the OBDII connector on lower drivers panel under dash.
7. Remove 4 7mm bolts from lower drivers panel
8. Disconnect electrical harness from panel to remove (pinch blue connector)
9. Disconnect parking brake release cable under dash from the lever (push cable grommet out of the holder and diconnect end of cable.
10. Remove single 7mm holding courtesy light to drivers panel
11. Remove 4 7mm bolts and remove panel - feed parking brake cable through the hole in the dash
12. Remove three 7mm bolts at instrument cluster (one in middle on top and two underneath)
13. Start to pull out the dash trim bezel, enough to push the back wiper/back hatch button out of the bezel, allowing you to disconnect the harness.
14. Open glove box completely by pushing up the spring that keeps it from falling open.
15. Remove air bag harness (yellow wires) next to main harness, and remove main harness by unscrewing middle bolt. There are two blue clips that I pulled out, but can figure out if I needed to or not. Remove at your discretion.
16. At left side, remove harness from headlight switch and remove bezel.
17. Remove radio (2 7mm bolts if stock). Two harnesses and antenna to remove. Now, if you have the cassette, you can either remove the center console or feed the cassette umbilical through the dash. I ended up doing both. To remove console, pull out cup holder rubber and remove two 10mm bolts. Open storage pocket at arm rest, pull out center, and remove two 10mm bolts. Center console is free. Either disconnect cassette wiring or if you have help, when the dash is free, take it with you. I fed the wires from the radio area down out of the dash, but later removed the center console anyway. If you feed the wires, you do not need to remove the center console.
18. Remove speaker grills under windshield - 2 7mm bolts. On the passenger, if so equipped, twist the light sensor (a quarter turn I think) to remove and leave the sensor in the dash.
19. Remove defroster grill. Careful - delicate. There are clips on the top (by windshield) and bottom (toward interior of car), four pairs. Remove light sensor as above.
20. Remove 6 upper bolts: one in each speaker bay and four in the defroster duct.
21. Remove 8 bolts and L brackets on either side of the steering column.
22. Remove 1 10mm bolt behind where brake release was, and one behind the glove box.
23. Check to see if the passenger door plunger is wired. If not, you'll know now it, and not freak out about it later.
24. Remove the box at the head of the center console. It has three harness connectors on the left, and they are labeled by color. Two clips and the box should come out.
25. Make sure the gear lever is down in 1st, and the steering column is lowered in the tilt function.
26. Pull dash away from windshield. It will fall against it's own stop. Lift it up off the pins that it hinges on, and it will be free. If you are careful with it, you can take it out the passenger side as is. Help at this stage is awesome, though I put the dash back in myself.
27. Pretty much anything in the middle that is black plastic is now coming out, but as one unit. The vacuum module in the front does not need to be disconnected. Let's start with the worst one: Inside the air box in the engine compartment is one of the bolts. There is a spot labeled "cut here for service." It's just to the left of the heater hoses. Cut that out with your utility knife. Not too deep, there is a plastic panel right below it.
28 Remove three 5.5 bolts and remove cover. Some earlier models had a blower resister here.
29. With a ratcheting wrench or a 3/8" ratchet and deep socket, remove the one bolt in there which will be shoved up against the filter on the left. Be calm, take your time, it will be a while.
30. Over to the right, there is one bolt holding this plastic box to the firewall. Remove it. Near the heater hoses is a stud that protudes from the firewall roughly an inch. Remove the nut.
31. Pull the hoses. You'll lose maybe a cup of coolant here.
32. Inside, passenger floor. At the top of the carpet under the box are three legs. The outside ones are threaded, and you can see the bolt head in them. It is on the engine compartment side. In the middle is one bolt you can remove.
33. On the two outside legs, most people, it seems, just cut them. I did. After bolting it all back together, I shook the unit hard and couldn't find a reason for them. At any rate, I cut the plastic above the bolts and left them screwed into the plastic.
34. Now the box should shake pretty easily. Don't forget that it sits on a saddle that feeds the floor heater ducts for the back seat. There will be a tiny bit of resistance here, but not too much. If there is resistance pulling this out, double check for bolts.
35. As you start to pull the unit out, look for vacuum or electical connectors that need to come out. Top right, there are two, I think. I had taken them all off, but found most could have stayed.
Now that the box is out, yank the two bolts on top of the heater core, remove it. If your foam is OK, reuse it. It holds the core nice and tight and keeps the warm air where it should be.
36. Rejoice! You are more than halfway done. I spent 6 hours removing and a little over 4 hours putting it back.


Good luck!

oh gawd......its getting into the high 30's here and i need to do it but i dont think i can. damn it.

Adam Crosier,

You can try http://imageshack.us/ to host the pics. They will resize the images and give links to post in forums.

Alternatively, and I have no idea if they host any photos on the forums, is to get the images resized using xp power toys image re sizer at the link below:

http://www.microsoft.com/windowsxp/D...powertoys.mspx

Link is listed on the right side of the page. The program lets you right click on images to resize instantly with renamed files. Resize them, and edit your post with pics using the forum tools. (Insert Image)

PM me if you need any help. Photo's will help big time with anyone else thinking of tackling this project.

Pictures uploaded
 

Hey guys,

I uploaded a bunch of pictures to an album on my profile here. I labeled the pictures by the step number from my earlier post. These are all 16% of the size of the original picture. If you want larger, PM me and I'll send it to you via regular email.

When I was uploaded, I noticed a couple of things I left or was wrong on. The box at the head of the center console... you need to disconnect the wire harnesses on the drivers side, but you can't take it out until after the dash is removed.

When I originally was updating my notes, I had forgotten to write that when the dash is disconnected but still on the pivots, check for wires that are in your way, from, for example, aftermarket stereos, or harnesses you have that I didn't.

Hope that helps!

If you wouldn't mind emailing the full resolution pictures to me (bf.com.admin@ g m a i l . c o m - take out the spaces), I will host them on my photobucket account and put them into the how-to above.

i have the dash out and the bolt in the housing engine side but i cannot get the cover off how do i do that

PLOW did you get the nut next to the heater core hoses and the screw on the evap box on the engine side? They are even with each other on the fire wall about 6" apart.

It's that stud that sticks out an inch or two. Yank the nut. There is also the bolt that goes through the housing to the left of the heater hoses. That's the one I never read about and had to figure out. It is roughly in the middle of the HVAC assembly.

Pictures!
 

I finally got the high res photos uploaded to a photobucket account. I put a link on my how-to list on page 2. The pictures are named by the step to which they correspond. When you open the album, click on a picture, and scroll down. You'll see a description of the step (close to what I wrote in the how-to). If you click on the picture again, it will go hi-res. The only thing I can't figure out is how to put them in order. So, just look for the step number. Also, I threw a couple pictures just of how things look. I think seeing the firewall side of the HVAC unit is helpful to see exactly where the bolts are that go into it. I also took pictures of each of the main parts in case I needed to see the bolt holes. I'll post them up too when I get a chance.

Excellent! I'm sure this will help alot of peeps. Maybe a moderator can sort through and edit a good final how-to?

Thought I was home free, until I went to plug the wire harnesses up. I discovered the passenger door chime harness MIA. I pulled the dash back off and I can't find it. Can anyone tell me where there's is on your Blazer. I hoping that I didn't rip it off somewhere. I have all the others not problem but just that one is MAI.

Hey, I responded to your message, but this will totally throw you for loop, that's why I wrote this step:

23. Check to see if the passenger door plunger is wired. If not, you'll now know it, and not freak out about it later.

I haven't looked into how the thing works without wiring, but it certainly does. If you don't remember taking a wire off the back of the plunger behind the glove box, don't worry, it's probably not there.

Wonderful Pix / Tutorial........I did mine on a '99 Bravada last month. The only problem I have how, is the heat blowing only gets up to about 80 to 100 degrees from the vents (Defrost, Vent, and Floor). Everything blows through the right vents, controls work, new core re-flushed. I've changed the T-Stat (even though the engine always seemed to be operating at the correct temp (195-200ish). Not sure what to try next. Maybe radiator cap? Fluid is always full (though it's probably not diluted adequately) Bottom line, when it's 11 degrees outside, it's still cold in my Bravada when it only blows 80 degrees from the vent. I've confirmed the vacuum actuated doors work. The blend door actuator moves (by feeling the fitting on top of the electric actuator - turns); however, I'm not sure if the blend door is actually moving to the extremes. I did the fuse pull thing. Any suggestions?

I read that the control unit needs to relearn what the temp range is. The controller might think 80 is hot, for example. Apart from an actual mechanical or vacuum failure, you might have to take the battery off and have it relearn. That's the extent of what I know about it, since I couldn't find a procedure. I just started driving again, and it works good now. Before the replacement, it only blew hot air if I put the mixture dial all the way warm. If you find the recommended procedure (if there is one) please post it - I'd love to know what it is!

Thnx Adam, you are right. I installed the dash and hooked everything up. The heat is back and everything is working with no problems.

Baffling but true! One of these days when I can pull myself away from the rest of my life, I'll try to figure out by what magic the door plunger functions without wiring. But, for now, I'll just figure it has something to do with the incredible power of my mind asking the light to go on when the door is opened. Man, I'm sure going to be disappointed when I find out what totally explainable thing the engineers did when they figured this out.

Heater Core sucess...
 

First off I have to big a BIG thank you to adam for the "cheat sheet" .. I started mine today around 9am and finished around 4 pm... 7 hours and I've never done one before.. and had to run out fo a few parts.. but all in all its not that bad.. there are a few suggestions I would like to make for anyone looking to do this ..


17. removing the center console also applies if you have the bose stereo system ( like my gf truck does) try to do this before you drop the dash to make you're life a little easier.. also to disconnect the hvac control unclip from the "longer" black tabs... what looks like a small disc with a bunch of holes and hvac lines is what should come out... makes life easy

26. additional step... make sure your antenna clip is disconnected..( took a minute to figure out what was holding it..

29. ok well here I'm impatient... so after feeling around a bit and looking in the hole with a mirror.. I made a 2nd hole in line with the "worst bolt" .. which I took pictures of.. saving myself the aggrivation.. and then sealed it with metal faced "duct tape" I'm willing to bet doing this saved me 20 minutes and ALOT of cursing.. I used a 3/8" ratchet 6" ext+3" ext + 3/8" universal + 10mm deep socket.

If anyone wants the pictures I took feel free to pm me while I figure out how to get them posted on here for you.

AWESOME write up thank you...

Just wanted to say thanks for the replacement summary!

I did mine yesterday and it took me just under 10 hours to do. Big thanks for the heads up on the lower bolts you're supposed to get from the engine compartment side. I took a dremel and cut the plastic around them and it probably saved me 2 hours of time. Now it's all back together, fits perfect and works great. This summary was a lot of help. Thanks again :icon_goodpost:

Looks like I'm next on the list to replace the heater core. :(

You can do it! Hang on to the list, check out the pictures. Other than a couple of the bolts, (and you know where they are, even) it's not all that physically hard. Just label like a maniac, and check, not only the connections of wires, but also how they're routed. Planning to do it is much worse than actually doing it.

I just did the same thing with my hinge pins last weekend. I'd been putting it off for some time now. I bought the pins. Put it off long enough to lose them. Bought another set. They sat around. Then I bought the spring compressor (can't imagine doing it without it, by the way) and then finally dove into it. It took less than an hour, and was pretty much cake. Good grief.

Haha thanks. I've always DREADED taking apart the interior. I'll do anything thats gritty, dirty, greasy, heavy, whatever. But the plastic parts and all the little wires and pieces of the dash is just intimidating.
I'm about to order the replacement... and I'll have to tackle this memorial day weekend. I plan on using scotch tape and bits of paper to label the hell outa everything. The pictures are awesome too... so the laptop will be my best friend out there in the garage. :)

Quick question before I continue... if the foam is in bad shape, is it easy to find? I haven't found it on rockauto's website yet.

Can't answer on the foam, but I'll add this: the heater core replacement I bought was slightly different than the stock one. I was able to get the foam off of mine without much difficulty, but it was a very tight fit in the box due to the new shape.

However, my foam also was clean, and I think this is important. I was absolutely shocked that mine wasn't saturated, but my core had just barely started to leak when I replaced it. If it was soaked with antifreeze, I don't know I would have tried to reuse it. I imagine you can get this stuff at most decent auto parts stores or even a craft store. If I remember correctly, it's maybe an inch wide, maybe a quarter inch tall, and has sticky tape on one side. If you can come up with something similar to that, I'd use something off the shelf before reinstalling something wet.