Ok, so I'm restoring my 73 240, and ran across a few threads about the Gen system A/C unit which I plan to install in the future.

I read where the fresh air duct up in the cowl wont be needed. So I just finished making a new duct and patch repair to weld in. The question is, a, I spitting in the wind to do all this? Should I just weld in a blank and be done with it?

Edited October 7, 20204 yr by DC871F

I'm not familiar with the A/C unit, but how did you get that chimney out?

2 hours ago, Freez74 said:

I'm not familiar with the A/C unit, but how did you get that chimney out?

It wasnt easy. Drill the spot welds off of the rain gutter over the vent (the easy part), but then you have to get in there with whatever you can find to cut out the duct.

If yours is rusty like mine, then actually thats an advantage as it already weak so you just start hacking at it. If your dash is out you can come up from underneath, if not, it may take a few beers and profanity.

Edited October 8, 20204 yr by DC871F

Mine looks rusty from what I can see of it, but it doesn't seem to have penetrated the cowl yet.  Just curious what the proper access procedure is, doesn't look easy.  If your air conditioning system does not need outside air, I suppose you could just put a plate over that hole and seal it up.  But, then where would the vent selector in the center dash panel get air?

My main beef with the aftermarket types like this that do not use the stock blower setup, is the lack of a vent. Main reason why I stayed with OE, but others say you do not need a functional vent, could just roll down windows. I am not convinced but anyway if you are going this approach, then completely useless to fab up a tunnel just to block it off.

Personally I don't get the appeal of the after market types. The OE unit works well, is VERY simple and has little to go wrong and is well... OE.

The biggest deficit was the expansion valve NLA status. there are brand new evaps that are setup for commonly available expansion valves. they are a bit pricey at about 300$ but given the engineering required to fit in an aftermarket, seems like that is a good deal.

get a modern compressor if you must, and a PF condenser, convert to R134 and you have a thoroughly modern system setup that has fully functional controls including the ability to vent in air for those that have more moderate temps and don't like the sound if wind from open windows.

I am also thinking a little bit down stream here, but if I ever sell my z, I suspect originality will be king like it is in the 240 segment.

OH SHUCKs, I just saw the 240z is what we are talking about, ok I retract all the above unless you are talking a 280z, the 240z AC was always lousy. Just another reason why I prefer the 280z over the 240z. I don't race, I do live in high humid and temps so the 280z superior stock AC makes me prefer them over the OE 240z lousy dealer added AC.

Edited October 8, 20204 yr by Dave WM

If it were me I would repair the chimney to factory and then block it off in a reversible manner. At some point in the future it may make monetary sense to reverse these changes

14 hours ago, Patcon said:

If it were me I would repair the chimney to factory and then block it off in a reversible manner. At some point in the future it may make monetary sense to reverse these changes

Great minds think alike and I agree, I kind of have to after making up a new chimney already.

I figured I would make up a panel with to fit underneath the dash with some rivnuts and use a gasket to seal it off. 

So whats the deal with not running fresh air vent with the VA system?

2 hours ago, DC871F said:

So whats the deal with not running fresh air vent with the VA system?

its pretty complicated to get the various duct work to make that happen without purpose built air box, the VA is a generic unit design to just take in cabin air and heat or cool it. trying to plumb from the chimney to the intake would require more custom duct work, a way to operate the blend door, all outside of the VA control design.

Edited October 9, 20204 yr by Dave WM

I’m going to install a VA Mini in one of my 1971s.  Do I have to seal (weld) off the duct or just close it?  It may be stupid question, but until I read this, I hadn’t thought about having to seal something off.  I have everything removed from interior and am about to order the ac unit.  I’m having the dash  refurbished and cleaning up the wiring harness.  

one question I do have is should install the interior first or the AC unit?
 

Any details regarding the VA AC install are greatly appreciated.

Edited October 11, 20204 yr by HappyZ

the chimney is sealed off by the old AC air box (there is a door that opens to the cabin or the chimney), so you lost that when you removed it. Now you just have a big gapping hole, so yes you have to fabricate something to close that or you will have a massive constant inrush of air from the cowl. I would just get a plate and use some silicon to seal it from the bottom, rather than welding up around the cowl and risking a leak. If the chimney is in good condition and the factory seam seal is in good condition you only have to worry about air coming in. If you start welding up around there you would likely damage the seam seal so you would have to really dig into the whole setup to make sure its water tight. You should look very closely around the chimney now that its all exposed to asses what needs to be done while the dash is out.

Edited October 10, 20204 yr by Dave WM

I would use some foam sheeting from home depot and some clear latex caulk. easily reversible and doesn't  interfere with future painting