I'm getting ready to start swapping motor, tranny and full interior from a 2001 camaro into my 1991. My question is whats everyone doing with the heat and a/c ducts. I would like for everything to work correctly as far as switching from defrost to floor or the dash vents. Has anyone tried to switch the whole heater and a/c system from a 4th gen??? I've heard that the blower moter won't fit under the dash.

 

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The easiest way to handle it is to trim the 4th gen duct to fit the 3rd gen box. Some people have done a complete swap of everything but it is very time consuming. I could never find any straight forward instructions so I had to wing it. But I documented it on my post. Search for complete interior overhaul and check out what I did. If you have any questions you and pm me.

 

There is a thread on here that shows exactly what needs to be trimmed to fit the 4th gen dash to the 3rd gen box. Thats what I used for mine, pretty easy to do and straight forward. From what I remember, its the easiest way to go, I know you can use the 4th gen box, but it did require quite a bit of work, mainly the defrost part of it. I can tell you that there is one portion of the selector switch for the vents that does not work because it was not a choice on the 3rd gen selector, thats of course if you use the 3rd gen box.

 

I did that also - just trimmed the 4th duct to fit the thirdgen duct and found that is kind of helped to support the dash as well. I have seen people use flexible dryer vent or something like that on other cars. I could not get the bottom part correct for mine, I had all lower heater air going to the drivers side and may have to make some kind of air splitter in the future.

As far as swapping over the 4th gen fan and lines, not much point to that for the work involved. Plus, the 3rdgen heater fan is fairly easy to swap out and might cost $25 new. The 4thgen entire a/c setup would be better for R134A but not that easy to install. I would suggest finding ways to improve the a/c in a thirdgen R-134A setup if better a/c performance is desired. Rockauto sells a direct replacement thirdgen spectre 73231 condenser for a 85?-91? setup that is supposed to be an improvement over the stock thirdgen condensor. Variable orifice tubes are supposed to help especially at lower RPMs. 4th gen F-body dual radiator fans help.

 

Thanks for the comments and suggestions, I will probably try and keep the 3rd gen stuff and trim to fit. Thought it might have been better the other way since I had all of the 4th gen parts ( I even cut the firewall out of the 4th gen donor car to use as a template, lol.) I just ordered the cam for my lS1 and a tubular k member, tranny mount for a 4l60e and a wonder bar from spohn. When they show up my car is getting dismantled and the fun begins. Will keep progress posted.