From looking at the photos, it looks like you can have heat or defrost but not both.

That rules out this system for me.

18 hours ago, MM569457 said:

I found a possible solution. Autoacsolutions.com. A but priced, but it appears to have everything I would need.

https://autoacsolutions.com/products/ac-kits/add-on-air-conditioning-heat-and-defrost-air-kit-with-integrated-controls-for-75-76-77-78-280z/
 

I’ll need to see if the dial switch can be switched for a 280Z slide lever.

Semi-interesting that they say it's for Lates (74-78) but their pics show a 240Z dash and center section controls...

Pretty sure @carcrazykentried to install this kit on his 76 280z and could not get it to work and ended up sending it back.

On 8/18/2023 at 7:13 PM, Jeff G 78 said:

Thanks Dave.  I'n in exactly the same situation as the OP.  I bought my '78 280Z 33 years ago not running.  I removed the A/C compressor when I bought it, so I have no idea if it worked or not at the time.  I have all the parts, but without knowing the condition of any of the components, is it worth keeping?  I now live in Phoenix, so a feature that added weight and wasn't all that important back east, is now a must-have.  I'd like to at least keep the HVAC unit and maybe do a blower upgrade, but I just don't know.  I think the OP has exactly the same dilema.

If you pulled the compressor back there and didn't seal up the hardlines to the evaporator, chances are the expansion valve components inside have rusted and it may be Borked. Here there's a much less chance of that happening. You might see if you can push A/C cleaner through the liquid line (at the firewall?) and catch what comes out the suction line in a rag.

If your expansion valve is OK I'd say it's definitely worth keeping. It's pretty easy to flush all the other parts. Get a new Sanden, have a couple of hoses made for the compressor conversion, replace the dryer, charge with 134a...

in that 240z pic you also see a big piece of carpet in the passenger footwell under the dash, I presume there to hide all the hoses etc...