Replacing the heater core has been a pretty major undertaking, and with the NBs being between 17 and 24 years old those remaining ones will have either had the job done, or will soon have to have the job done. I have pulled out a number of NB dasghes, but never with a view to putting them back in, so I never took a lot of notice how they were put together. As a result I learned a lot from this exercise, and hopefully I can make your heater replacement faster and smoother than mine. While I found resources on removing the dash, replacing the heater core was another matter.
Lessons learned1. Take lots of photos as you go.
2. Remove the seats, drivers at minimum, but if you are pulling the dash remove both - lots of room, easy access. I also removed the steering wheel - that requires removing the bomb. Disconnect the battery before working on the bomb - if that goes off it will kill or maim you. Open the softtop/remove the hardtop, pretty obvious really. Pulling the dash requires removing ALL the trim around the windscreen. I just googled removing the dash, there are a number of guides for this.
3. Bag all the nuts and bolts, I used ziplok snack bags mainly, with some larger ones for bigger bits (every garage should have a full range of these on tap - they are so handy and save so much grief later on). LABEL THE BAGS! I ripped pages from a small spiral notebook, but anything will do, just label them. The advantage of the ziplok bags is that you just put the description in the bag and seal it in, no worry about smudged writing or the like trying to write on the bag itself.
4. Yes you can (apparently, the internet says so) take the core out without pulling the dash and ripping out all the hvac. However, I had great difficulty removing the core from the heater box, even though it was out of the car and I had full freedom of movement. The reason was that the foam used to seal the gaps around the core had bonded to both the core and the plastic of the heater box, and it required a major effort to break that bond. It could not have been done in position inside the car. YMMV, but be prepared to pull the heater box if the core does not want to coooperate. Just be careful with the plastic heater box, that stuff is getting old, and is not as strong as when it left the factory, the amount of force I had to use must have gone close to breaking the plastic but I got away with it.
5. I pulled all three boxes - heater, aircon, blower just so I could figure out how to get the heater and aircon to mate up. I could have left the blower alone, but you can benefit from my hard won knowledge
Replacing the coreThe only tricky bit here is attaching the piping. The NBs use 'o' rings and finnicky little clamps to join the two pipes to the heater core. The instructions say assemble dry, I used some red silicone - too much, wrong place. If you want to use silicone, maybe just wet the 'o' ring with silicone, put the 'o' ring on the pipe, smear a LITTLE on the 'o' ring, then assemble. Note the orientation of the clamps in the photo.
Check that the pipes sit snugly in the clamps and on their housings on the side and rear of the heater box. If they are not sitting like they left the factory (ie there are gaps) you have done it wrong - don't ask me how I know this but see the photos for how they sit.
I took mine to the radiator place where I got the replacement core, where they fixed my overuse of silicone, and pressure tested the assembled heater (latter was a well spent $20 for peace of mind). You can get around all this by buying an NA heater, which is copper and comes with the pipes attached.
Cleaning the joinersGood bloody luck with that. Except that all the old foam/felt will be cactus, and has to be replaced. Paint scraper FTW, with your selection of jungle juices to remove the old adhesive. This is the worst part of the whole process.
The joinersEasy one first - blower to aircon. 25mm felt strip might have been a bit wide, 15mm might be better and make it easier to get the bolt in. I replaced the short bolt with a longer one, but my felt was probably too bulky, get the shortest nap you can. Note, if you have taken all three out, the blower is the first one back in.
The heater box to aircon join was confusing. It seems designed for the aircon to be the last of the three to be installed - the mating aircon fitting slides into place with the joiner already installed on the heater box. I could not see how you could assemble them in order of blower first, then aircon, then heater ( the corollary is that I can't see how just removing the heater is viable, as getting the heater back in place does not seem possible even if you can get it out in the first place). Even doing it this way I couldn't see how the felt would seal the join, the gaps were too big. I ended up using felt strips everywhere except as shown in the photo. This was where the biggest gap was, and the felt was not going to cut it. So I put the rubber strip inside the join, so that the aircon fitting slid in beside the strip of rubber. It looks like there may be a restriction of the airflow, but in reality it just reduces to the size of the heater box air entry a little earlier.
The heater side of the joiner
The rubber strips sealing the gap between the aircon and the joiner
Felt (3mx25mm)
Rubber strip
At this point I was ready to start putting the dash in. That will be the subject of a separate post.
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- stripped the thread in the LCA captive nut, and nothing I can do will get the bolt out that is attaching the shock to the LCA. Took the LCA down to a local engineering shop, and today they tell me the shock is out of the LCA, so that is good, now I have to find a NB RR LCA - I have one rear LCA, but it is a LR (of course!). Turns out I have LCAs for three corners, but not the one I need. I'll have to get the poly/bronze bushes out of the old one and into the new to be fully mobile, but in the short term I have a NA RR LCA which can go in while that is happening.
