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How do I remove the heater core from a '72 Chevelle SB with AC? It was leaking onto the passenger side floorboard so I rerouted the coolant line temporarily until I could figure it out. It looks like there are a bunch of rivets that hold the plastic box under the dash?
 

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It's not that hard...but not much fun either. Have a 72 also, that did the same thing two months ago. Yes, there are bolts and rivets extending form the engine compartment firewall that need to be removed to drop the "plastic box" i.e heater assembly holding the heater core. You'll also need to remove the dash pad to get to and remove the AC distrbuition duct/duct hoses that will have to be removed also to get the plastic box out. Alsng with pushing calbes and the like out of the way.

I went out and bought the 72 Chevelle Factory Assembly manual (all repo web sites have them for sale and Ebay) and it provided a number of pictures to help me visualize where everything went and came from.
 

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If it's anything like my son's 70 it's not too hard. There are four nuts on the outside(firewall) in the engine compartment, two on top two on bottom. The lower one closet to the engine can be tricky to get to. There are two screws inside that attach to the firewall. One about mid way between the passenger side kick panel and the tranny tunnel and one on top alittle to the right of the lower one. It makes it easier to access the top one if you remove the dash pad. You'll also need to remove some ductwork to gain access to things. The "suitcase" will then pull/fall off the inside of the firewall. Remove things slowly as thre are a lot of vacumn lines and wires. If you remove any wires or lines note where they go. You don't need to completely remove the box but you can again just note where things go. Then you'll remove the cover over the core and replace. Reinstall in reverse order and that's about it. One thing I might add is be careful when you put it back in, I managed to get a vacumn line caught between the case and the firewall so I had to losen it and get it out. I also found it easier to remove the pass side kick panel. Good luck, Pete
 

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Discussion Starter #4
Does the heater box go all the way across the passenger compartment? Do I have to remove the AC box under the hood next to the coolant lines?
 

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Heater core replacement for a 70- 72 chevelle:

This is the quickest way to do this. This applies only to cars with ac I don't know anything about non ac. you can remove your passenger side inner fender well or do what I did. There are 2 lower bolts that hold the inner fender well to the firewall. Mark a center point 7" straight up from the top bolt. Drill a 1" hole thru the metal or plastic. This will gain you access to one of the 4 heater core box nuts with a socket wrench. You can afterwards go get a 1" plug from a hardware store. This is sure better then taking off the fender and fender well if you can live with a whole in your well. I think gm should have put an access hole there to start with. Anyway after you get that nut off (and it is a nut not a bolt! the nut goes to a stud attached to the inner heater box.) the second one is right under the heater hoses and the other 2 are towards the engine and can be reached. Next remove dash pad (bunch of screws pointing up; don't forget the ones in the glove box). Then remove the center ac vent this is above the ac & heat controls, this lets you remove the plastic duct box like thing too. Then remove the passenger side foot air duct piece from the bottom of the dash. Remove the door jam sill plate so you can remove the kick panel. Squirt water thru your heater core or cap the ends because fluid will spill out on the next step. Now you are ready to pull the inner heater box away from the fire wall and let it rest on the floor. Undo 3 screws on top side of heater box. Where a control cable attaches. Leave the box sitting right there. Don’t even try to pull it out. Reach behind it and remove 4 screws that hold a backing plate on. Use a flash light and mirror if necessary. When they are out the backing plate with the heater core attached to it comes out. 4 more screws hold the heater core to the backing plate. Reverse the order with the new core. I would check the new core first for leaks if you can. I put it in line with my heater hose and ran the car to temperature to high temp pressure test mine. You don't want to do this twice. GM must have built the car around the core. I guess that why they call it a core. Hope it helps.
pete
 

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Heater core replacement for a 70- 72 chevelle:

This is the quickest way to do this. This applies only to cars with ac I don't know anything about non ac. you can remove your passenger side inner fender well or do what I did. There are 2 lower bolts that hold the inner fender well to the firewall. Mark a center point 7" straight up from the top bolt. Drill a 1" hole thru the metal or plastic. This will gain you access to one of the 4 heater core box nuts with a socket wrench. You can afterwards go get a 1" plug from a hardware store. This is sure better then taking off the fender and fender well if you can live with a whole in your well. I think gm should have put an access hole there to start with. Anyway after you get that nut off (and it is a nut not a bolt! the nut goes to a stud attached to the inner heater box.) the second one is right under the heater hoses and the other 2 are towards the engine and can be reached. Next remove dash pad (bunch of screws pointing up; don't forget the ones in the glove box). Then remove the center ac vent this is above the ac & heat controls, this lets you remove the plastic duct box like thing too. Then remove the passenger side foot air duct piece from the bottom of the dash. Remove the door jam sill plate so you can remove the kick panel. Squirt water thru your heater core or cap the ends because fluid will spill out on the next step. Now you are ready to pull the inner heater box away from the fire wall and let it rest on the floor. Undo 3 screws on top side of heater box. Where a control cable attaches. Leave the box sitting right there. Don’t even try to pull it out. Reach behind it and remove 4 screws that hold a backing plate on. Use a flash light and mirror if necessary. When they are out the backing plate with the heater core attached to it comes out. 4 more screws hold the heater core to the backing plate. Reverse the order with the new core. I would check the new core first for leaks if you can. I put it in line with my heater hose and ran the car to temperature to high temp pressure test mine. You don't want to do this twice. GM must have built the car around the core. I guess that why they call it a core. Hope it helps.
pete
Hello,
This old feed was very helpful as this job was a little difficult. It needed to be done on my 71 SS and it took me about 6 hours to complete with several brakes in order to prevent me from fire bombing the car all together :)
The step that describes making an access hole to get the the lower bolt/nut through the inner fender was omitted as I just drilled out the bolt/nut from the inside and punched it out. This bolt no longer exist and I stuck a foamy ear plug in the open hole to keep the weather out.
Respectfully Thank you for the helpful advise.
 
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