'99 blazer heater core removal

Hello everyone, I've hit a real snag and was hoping someone could throw me a life line. I was getting a strong smell of coolant in the passenger cab and the windshield did fog up the other night, but no other symptoms. No wet spot on the passenger floor, no noticeable loss of coolant and no other drips, leaks and or wet spots. From reading the other posts I narrowed it down to the heater core and have begun removal.
This is where things begin to turn...the dash is out and all removeable screws have been taken out of the core cover. I am at a loss, nothing seems to work!! It still seems to be fastened from the back. I have been going under my own assumption that the top half of the cover needs to be removed in order to get at the core, but this is merely my own hair-brained scheme, and as of yet seems fruitless. I have tried to get a chiltons or haynes but have had no luck in my immediate area, I will try to widen the search tomorrow but any tips would be sincerely appreciated. Thanks in advance

If you get an answer let me know. I am in the same boat.

Well I don't think what I did will help you. I just went inside check the forum, wrote the reply and then went back out and tried again. I had already removed the 1/4 screws from the cover I just did not break the steal. It was stuck and I was afraid to pull on the cover. I did and now I am ready to start buy the new core.

Did you say that you did remove the cover? I have gotten all the screws that are visible and even the few that aren't, but it just won't come free. I got the haynes and it helped me find the bolt in the engine compartment, but still no luck!! The top half of the cover will move but it doesn't even seem close to coming off. I'm losing my mind here. The haynes doesn't mention it but i heard something about the fender liner needing to be removed in some of the older ones? could this be the case?

I just finished. If you are in the engine removing the bolts you are too deep. Don't try to remove the whole heater assembly. Just remove the cover. It has very small screws. They have a head about 1/4 inch. Once the cover is removed there are two retaining straps. Remove them.

Congratulations!!! I think I can imagine how you feel right now! The only screws I could be missing would be behind the cover, and in that case, I will never be able to get them. I have tried all I can think of and unless their is a clip or screw in the back, I don't know what could be holding it. I was wondering what year you were working on and If by chance you could tell me exactly what you did at this point in your travels. I would be eternaly grateful. Thanks in advance.

my car did the same thing (smell of coolant and smog on window). it is the heater core, it happened this friday and repaired it today. i was looking on the internet last night hoping to find someone that had a clue how to do this but i did it today.
It was a very diffucult repair. The entire dash is removed, panels, radio, heater controls. however ,leave the stearing wheel on, just put a towl over the plastic part of the steering colum and you can rotate the dash then pull it off. once you have everything off the heater compartment is in two piece but dont worry about taking them apart, this will only cause more grief since the mechanisms controling the air flow will be displaced from their seats (although i did have mine in two pieces practicly, so i am assume that it doesnt help but maybe it made it a bit more maluable to work with). Loosen the one bolt going into the fire wall on the bottom of the heater compartment. there are two bolts coming in from the engine comparment on either side of this bolt, if you can get to them you have to much time on your hands. I would suggest cutting each plastic rib or use and easy out to back them up ( i just broke the f#@Kers). These two bolts coming in from the engine compartment are not in the aircondition compartment but below it, i think you may have to take your coolant system out to get at these two Titanium Nitride looking bolts. In the engine compartment there is a bolt that holds on the protective mat for the air conditioning condensing unit, it is the futherist bolt towards the center of the engine, remove this bolt. The heater assemble (in the cabin) will now rock about and will be loose. There is one bolt that holds in on that is located in the air conditioning chamber. (so to recap briefly there are a total of three bolts 2 of which seem impossible to get at and one you can get (the one in the coolant chamber) by rocking the heater assembly carefully towards the passenger side door then reaching your hand and a socket (i believe 9/32) and lossening it one 1/4 turn at a time you can loosen this screw that actually is threaded into the heater chamber (snake your hand though the compartment of where the cool air comes in , the screw is on the side closet to the passenger side -- the heater assembley must be pulled, but be careful you are pivoting the whole thing at the same place you are loosening the bolt. Putting it back in is also fun. once this bolt is out then you can pull the whole assembley out, if you understand this and you have gotten this far the rest is down hill.......i am not a memeber of this site and only got a memebership because i read your response last night and figured i would give you some tips since i did the entire job in about 14 hours today. the heater assemble is secure with those two screws busted out, no rattles and I plan on expoxying them back on each other one day.....

i have a 2000 blazer, i did not see any retaining straps. older blazer are a very different construction. --- you had a block to recieve email, so anyways good luck, it is a pain in the ass!

Wow it sounds like the 2000 blazer is very difficult. I have 96 blazer. Once the dash was out there were four or six very small screws that held the cover on the heater core. I removed the screws. Opened the cover and there was the heater core. To remove the core I took off the hose, remove a screw by the outlet, and then remove two small silver straps. These were right on the core itself.

Thanks 14 hrs , Thanks bob!! I didn't realize I had my email blocked(don't know how to unblock it either). Your directions are right on from what I remember,14. I will be heading out to the garage in a few minutes to give this a try. The bolt I was talking about removing on the inside of the engine compartment was inside the blower motor housing. I gotta thank haynes for that one (man is it gonna be imposible to get back in!!) They made it sound like it was vital but never once mention the two bolts (with the black tabs) coming in from the firewall. They are gettin snapped off the minute I get out there!! I definitely would not recomend the haynes and I heard that the chiltons sucked too, so what gives? Thank god for the internet. I'm gonna go snap off those tabs and try loosening the bolt in the a/c duct. We'll see what happens I guess. Thanks again and I'll write back with the positive results.... I hope!

I got busy with other stuff today and was just able to get out there and look for that bolt inside the A/C duct. For the life of me I can't find it! A I must not be looking in the right place. I'm looking in the top of the heater core cover, in the top center where the two holes are for heat and ac. Just to the left of the little door that opens over the top of the heater core. I've gotten my hands in the ducts but can feel no bolt heads? Thanks again in advance.

I've finally finished!!! I figure I owe the car gods something So I'm gonna post some instructions for removal that apply to the '99. I don't know what the differences are between the diff. years but upon review of the chiltons and haynes, they must be substantial! Haynes was just about useless, and from what I've read chiltons was worse.
I'm gonna go from the point that the steering column is dropped and the dash is separated. Do not bother with separating the halves of the heater core cover, remove the bolt going into the fire wall in the passenger foot well, this is easily accessible with the carpet pulled back. It is the black bolt attached to the bottom of the heater core cover, with the backs of two bolts coming in from the firewall showing through two black tabs on either side of said bolt. I cut these tabs with a dremmel, that was my decision you could also access through the wheel well liner.
In the engine compartment, I removed two bolts and one nut. The nut was the easiest, It is in the center of the firewall all by itself. Bolt one is inside the blower resistor housing. Cut plastic where it says "Cut here for service" inside against the firewall to the left of the duct opening is the bolt (remove). The other bolt is much easier to get, but not that easy and its attached to that exact housing you were just in!! It goes through the housing and into the firewall just under the heater core hoses,Remove.
Obviously you need to disconnect the vaccum hoses on the cover but everything else is self explanatory. I spent too much time to admit trying to find that last fastening bolt. I hope this helps you and good luck. By the way I'm not a mechanic so their are probably many things that a real mechanic would not agree with but this worked for me and could have saved me a ton of time If I knew this stuff first. GOOD LUCK.

Last Blazer;

Don't count yourself out! You found all the bolts discribed them with detail, found your mistake and corrective action (cutting tabs) and to top it off placed the info where others can use it. You sound like a damn good mechanic to me. I've had a 99 Jimmy for a month now and it gives out heat when it feels like it. I bought the Haynes and it seems useful for the torque values and a little more. I wanted to look at the core but haven't made that move yet. Your info helps me guage the time better. I did the sparkys last weekend and #3 is a real pain dropping the steering shaft. Best of luck with yours and thanks for the info.

Cheers/Ken

KTLT1 - Check your vacuum lines to the heater vents first if your core isn't leaking. (Advise c/o my local GM service manager)

I am searching on how to replace the heater core in a 2000, anyone know where I can get help with it?

I am searching on how to replace the heater core in a 2000, anyone know where I can get help with it?


Have a look at <http://www.sytyarchives.com/howto/viewarticle.php?article_name=heater_core.php&dir=climate_controls>;

This site worked great for me. Details to the core!

KTLT1 - Check your vacuum lines to the heater vents first if your core isn't leaking. (Advise c/o my local GM service manager)

Where exactly are these vacuum lines? Are they in the enginebay? Or do you mean heater vents in the dash?

Where exactly are these vacuum lines? Are they in the enginebay? Or do you mean heater vents in the dash?
Vacuum lines are visible when you remove the glove box and lower dash assembly. Apparrently the temperature blend door is electronically controlled, located on top of the heater core housing.

If you don't hear a vacuum leak and the blend doors appear to be functioning properly then they probably are.

Perform a reverse flush on the heater core only. Remove the two connections in the engine compartment and blast water through the output side of the heater core. When I performed this on my vehicle I actually forced sludge out of the input. Now I have a blast furnace again.

Try these before attempting to replace a heater core that is not leaking. Dexcool gels when in contact with air (bad rad cap) and tends to clog up the heater cores.

Good Luck !