Does anyone have explicit instructions on how to replace the heater core on a 1993 Volvo 940 non-turbo?
Any advice will be greatly appreciated!
Thanks,
OnlyVolvo

I have done this twice. The first thing to do is remove the heater hoses on the fire wall. they can be a real pain to remove after the core case is free. As noted above, the really hard case screw to remove is the second from the left on the top of the case (it is even harder to reinstall). will need a ~15 inch long screwdriver to reach. The easiest thing to do is to remove all! the other screws. Then grip the bottom of the case and rotate the case up. this will break the tab off. It is a tedious job. an afternoon to take apart and a second afternoon to reinstall. as noted above, the paper on how to do this is great and a must have resource. If there is a pick-n-pull near you, go and practice. You will end up taking apart almost all of the front dashboard.

If you're sure the heater core is gone you can just crush the copper nipples, hack them off so you can turn the ends up for access and then peel the crushed nipple out of the end of the heater hoses. In the 900s, the heater core nipples were caulked to the firewall to prevent water intrusion, which can make final heater core removal a bit more difficult. As I noted in my FAQ article, push the remaining nipples through the firewall from the engine side once the heater core straps are freed on the inside. I've also done this job twice and every time it gets a bit easier if you can only remember a few of the tricks for the stubborn parts and the minimum amount of dash that needs to be removed. That's why I spent all that time during the second one writing that long article so that I'd have something to reference the next time. I didn't have a digital camera, so Ari was later kind enough to add some pics, plus I was working with all black plastic in an all black interior. Regrettably throughout a number of FAQ revisions the article lost some if it's content. That final top screw is the major challenge, but with the techniques listed and a bit of patience it will come. I initially thought about breaking that tab, but that would be admitting defeat.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

I did a heater core on my 1993 2.0L turbo UK RHD (I see yours isnt). It was a bit of a swine, but using the FAQ its not too difficult. I really needed to keep using the vehicle for work so I just linked out the heater pipework in the engine bay where it goes into the bulkhead with a bit of 15mm copper pipe I had lying around and still keep it in the car just in case. All depends where you live I suppose but I think it was late winter/early spring for me so not too bad. Take lots of pics with your phone as you go when you replace the core, I remember from the faq that a couple of the screws on the box that its in are a bit difficult to get too and remember where you pulled the various vacuum hoses off from. Once youve made a start it wont seem so bad, but there is a lot of upside down in the footwell type action ahead so hoover it out first. I didnt worry too much about which one to buy, but probably plastic bad, metal good. Remember its just a small radiator in a box and would probably work if you taped it under the dash. Good luck and its so satisfying when it all works again and the carpet is dry!

The FAQ's were maintained by Steve Ringlee until the software was no longer available. I did my heater core after he had to stop updates. There is a fastener that is a real PITA to get to on the core enclosure. I discovered a route to get at it with a 7mm socket on a long extension and posted it. It would be best to tape the socket onto the extension.

That post is here:
https://www.brickboard.com/RWD/volvo/1627838/740/760/780/earned_heater_core_merit_badge_replacement.html

Randy
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Any twenty minute job is just a broken bolt away from a three day ordeal

Almost everything you need to know is here in the 700/900 FAQ. And you're welcome, this isn't a chore someone would want to take on without advice. It's regarded as one of the worst chores imaginable with our old 700/900 bricks, both for pros and DIYrs.
https://www.brickboard.com/FAQ/700-900/HeaterCoreReplacement.htm
Please support your brickboard, be it financial or other contributions, including posting back on how you make out.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now