2000 Chevy Blazer Heater Core Replacement

[dreamsteve]

For my first post, I want to paste over a post I did in another forum as I believe it may augment previous posts and help the DIY'er get a better understanding of the Heater Core replacement for the Blazer.

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!

[4.3_ftw]

y didnt you just bypass the heater core it took me like five mins to do that and now my truck runs great and stays alot cooler, so i have no heater w/e.

[dreamsteve]

While I was researching how to do the replacement, I did have it bypassed.

With the winter coming it was a luxury I wanted to have. Down here in Louisiana, you get a lot of moisture to go with that cold weather and you constantly have to keep your windshield wipers on.

That bothered me to no end. Auto Climate control rawks as well and I didn't want to miss out on that during the winter. Damp cold air sucks compared to nice and dry cold air.

[Slow_S10]

Excelent write up even without pictures! I just replaced the heatercore in my wife's Bravada not too long ago and I definately feel you on inventing some never before heard swear words as I went along.

Also for whatever reason the heatercore in my wife's truck ended up being different from the ones that almost every part's store and even the dealer had in stock. Of course like the intelligent person I am I purchesed the heater core before I delved into this project only to find out when it was time to install the new one that it did not fit at all. I ended up driving around for hours to every parts store in the area and I eventually found the right one at a Napa. That definately added a bit of excitment to the whole deal.

The main difference was the one her truck had in it had a rounded curved bottom while the ones all the other stores and even the dealership had in stock had a more squared off bottom and they wound not seat all the way down into the blower box.

[dreamsteve]

Strange. I actually had to adjust the cooling lines lower on the heater core to get it to fit myself but didn't really have a problem fitting in the heater assembly as the lines themselves have a bit of play in them to get them lined up (press fitted).

They did sit a bit to the passenger side at the hole in the firewall though and that made things tough getting the assembly back in to thread that damned bottom bolt in.

Glad you found a solution to your problem.

[Slow_S10]

Quote: Originally Posted by dreamsteve

Strange. I actually had to adjust the cooling lines lower on the heater core to get it to fit myself but didn't really have a problem fitting in the heater assembly as the lines themselves have a bit of play in them to get them lined up (press fitted).

They did sit a bit to the passenger side at the hole in the firewall though and that made things tough getting the assembly back in to thread that damned bottom bolt in.

Glad you found a solution to your problem.

I had to to that also. However the problem that I was running into was that the heater core did not fit inside of the blower box at all. Like once I put it in there the whole thing sat up agout 3/4" too high and there was no way to even get the cover back on.

Also for what it's worth once I rotated the tubes on the good core to line them up I applied some high temp silicone around where they connect to it.. I figured it was just a little cheap insurance.

[dreamsteve]

I didn't think of that. I have this nightmare that my "brand new" radiator cap will fail on me and take my heater core with it. lol that much work and I worry about anything making it bust

[Calvin51]

Excellent write-up and I saved it to Word. I know what you mean when you say that a 5 hour job turned into 17 hours with new vocabulary words. I was stripping out a '98 Jimmy and I found that the dash was the hardest part of the whole vehicle. If no one has ever tore into their dash completely, you are in for a new experience. Measured in "beer time" it was probably a case. LOL!!! I found that the cheap magnetic trays are a lifesaver when it comes to keeping the bolts and screws as there are a multitude of them in the dash.
Again...great write-up!!!