Heater box to defroster vent issues

Discussion in '1978 - 1981 Specific' started by Hobart, May 27, 2020.

  1. Hobart

    Hobart New Member

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    Hi guys. I'm working on a 1980 Z28 that is a project car my friend and I own, and we got it partially disassembled. It has been a bit bastardized. Among the issues is putting together the heat and defrost assembly. This car was originally an AC car, but someone took the AC out and installed factory heat and defrost, at least partially. Among the things I can't figure out is if I have an incorrect heater assembly or an incorrect defroster duct/vent assembly. You'll see in the pictures that the defroster duct actually sits right in front of where it should connect to the heater box, and actually interferes with the movement of the blend-door (if that's what you call it). Do any of you have any ideas?

    Thanks in advance. I have been lurking and learning from you all for quite some time, I appreciate all of your knowledge. IMG_20200527_163226.jpg IMG_20200527_163231.jpg
     
  2. ronzz572

    ronzz572 Veteran Member Lifetime Gold Member

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    The defroster vent in the car is for a A/C car. It won't work with the no A/C box.
     
  3. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    The hole in the firewall is in a different location depending upon factory A/C or not.

    it looks like someone tried to make a non-A/C under-dash box fit the firewall hole for an A/C car.

    It’s been over a decade since I took the heater box out to replace the heater core but I think that metal tab (in your hand, in the 1st pic) is supposed to align with that clip below the “door”.

    I don’t know if its the wrong heater box or defrost duct.
    Or...the heater box is simply mounted in the wrong place due to the location of the firewall hole.

    Decide whether you want A/C or if you want an A/C delete box under the hood.
    Then...Figure out which pieces will help meet your goal.
     
  4. Hobart

    Hobart New Member

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    The firewall is fairly butchered, and I know that the AC hole vs. the non AC hole in the firewall is different. I initially thought that the box was mounted too far to the driver's side, which would account for the mismatch. However, after taking it all apart; I found that the previous owner actually put some thought into reworking the firewall where the AC/heat firewall-hole mismatch was, and the blower's squirrel-cage hole actually lines up correctly. So I'm thinking I must have either the wrong defroster duct or the wrong heater box. I'm thinking that what ronzz572 said makes sense, that there is a different defroster duct for a non-AC car. Now I must find one.

    I don't have the original AC stuff, so it's gonna be a non-AC car.

    If only this car could tell me it's story! After pulling the carpet, I can see a cage was once welded in. With bars thru the dash, which were patched. Yet I have a stock rear end and original (plastic-injected) u-joints in the driveshaft. Very interesting...

    Thanks to you both.
     
  5. Hobart

    Hobart New Member

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    Yep, it looks like I have the wrong defroster duct. Here's a pic I found online of the whole setup, and I can see my defroster duct is different.

    Thanks again for the help! HEATER REFERENCE.jpg IMG_20200527_163226.jpg
     
  6. CamaroDoc

    CamaroDoc Veteran Member

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    I have the non-air duct if you need it. Doc
     

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