Removing evaporator from a/c box

Discussion in 'Troubleshooting & Diagnosis' started by valleyguy, Nov 21, 2019.

  1. valleyguy

    valleyguy Veteran Member

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    Can I separate the a/c/heater box at the firewall, or must I remove the unit as a whole??
    I just want to get at the evaporator. I would like to avoid having to dismantle the whole thing. The heat blows fine so I think the heater core is ok. Thanks
     
  2. Zspoiler

    Zspoiler Veteran Member

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    Its easier just to remove the whole thing the way it fits in there.
     
  3. dale68z

    dale68z Veteran Member

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    I removed and reinstalled the evap in my 71 one night after work. It took 2-3 hours. I just took off the side towards the engine.
     
  4. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    ^ I think that’s the way to do it if you want to clean it out and/or replace the evaporator.

    It’s a large unit that would be hard to wiggle out with the entire engine and hood in place. Removing a valve cover might buy you a little more wiggle room.

    I need to replace a heater core and I figured I’ve got half the work of replacing the evaporator already done if I have to remove the nuts for the interior heater box studs.
     
  5. DrPepper

    DrPepper Veteran Member

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    You don't mention what year car you're working on, but no matter, it's still going to be a PITA.
    I just replaced the evap core and heater core in my 81. I'd say the heater core was the worse. Everything under the dash had to come out. Even the brace that runs across the bottom of the dash.
    My evap core came out by just removing the engine side of the AC suitcase. I'd suggest removing the hood, the inner fender, and maybe the fender as well. (fender is optional.) And even with all these things removed, it was a pain. I'd work on it for a while and have to walk away. (didn't want to get mad and start breaking things) Had to do 'a lot' of wiggling to get it out. I was at the point where I thought I'd have to remove the exhaust manifold too. But by holding my mouth in the right position and saying the right words, very loudly, it came out. Installing the new evap core was a snap compared to removal.
    BTW, cold beer helps too.
    Good Luck.
     
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  6. valleyguy

    valleyguy Veteran Member

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    My car is a 71, 350 v8. I already have the inner fender off, to replace the blower motor. also got a lot of mouse crap out of the duct on the engine side with that blower removed. (I'm sure there is also more of that inside as well( Now, I figured I would examine/replace the evaporator core on the engine side as well, since it does not appear that this a/c system have ever been touched. I do want to work on the inside ducting as well, but that's for another day. With regard to separating the ac box in the engine compartment, most of the bolts are apparent, I even got the one stud in the rear by the valve cover (at the top); is there another lower bolt that I have to contend with; hard to see down there. and.. I do have beer ready.
     
  7. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    IIRC, There's two nuts on studs on the engine side of the evaporator case. (And a third one, in the lower corner, below the blower.)

    Sounds like you already found the upper one by the tab that sticks out.

    It's the lower one that's a total PITA to access around the exhaust. :crazy:

    I did my heater core when I still had exhaust manifolds.
    Now that I have headers, it might be even worse. :mad:

    upload_2019-11-22_12-57-22.png

    The nuts go on these studs from the under-dash box.
    The lower right one is the one you haven't found.
    upload_2019-11-22_13-4-56.png

    I don't know about the screws holding the halves together across the bottom of the case. I've only done the heater core before.
     
  8. valleyguy

    valleyguy Veteran Member

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    I found the lower stud down by the exhaust manifold, and finally got it off, what a pain. I also found the two lower bolts that hold the two halves together (closest to the wheel), can't see them but can feel them. I got one off so far, standing on my head lol, pondering now how to get that last one off, real close to the frame rail.. then I think I'll have them all....ps what is that left side arrow on your picture, it does'nt look like a stud.
     
  9. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Kind of hard to see in that pic. The stud is the brown thing, just below the lower heater hose connection. (The tip of the left arrow touches it.)

    You shouldn't need to undo that one unless you're pulling the heater box out from under the dash.
     
  10. valleyguy

    valleyguy Veteran Member

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    Well I got it out finally! just ordered a new evaporator. When I get ready to reinstall, what is the recommended sealant? strip caulk, seam sealer, ??
     

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