Is there a better way to get FRESH AIR in if you have deleted AC HW?
 

I am going through the heater backdate on my 3.2 and am seriously considering removing all AC hardware. Here is an issue that I am pondering:

Fresh air can only come in through the footwell and dash vents, and quite frankly, it sucks, even with the fresh air blower on. Wouldn't it be nice if it could be set up like most other cars and actually pump fresh outside air through the center vents that you can actually feel? Are we, as 911 owners asking too much? Seriously, has anyone ever re-worked the rats nest of pipes to acheive this? Oh, by the way, I still need heat for me and the windshield.

In the days when AC was still an option the center vent pumped fresh air into the car. If you remove the evaporator and hoses you will see how they plumbed it for the AC.
The following drawing from the PET shows the part [part is in red]you would need to backdate the fresh air plumbing.
The part number is 911-571-039-00 [distributing piece] the part in blue is the duct for the center vent.

http://forums.pelicanparts.com/uploa...1142697529.jpg

More info here:

http://forums.pelicanparts.com/showthread.php?s=&threadid=220104&highlight=911571 03900

I just went through this and ended up using the following threads for guidance. I have fresh air blowing through my top vent now - much better!

http://forums.pelicanparts.com/porsche-911-technical-forum/220104-86-89-carrera-w-out-ac-what-comes-out-dash-vents.html

http://forums.pelicanparts.com/showthread.php?s=&threadid=235950&highlight=fresh+ air+blower

A bit off topic, but I was looking at the plumbing for the fresh air/heat and AC and began to wonder if the fresh air system and the A/C system could be combined more efficently and share all the cabin vents intead of spliting them up the way the factory choose to do. AC on the windshield is a great way to defog and more vents for both systems would help them greatly. I'm also trying to figure out why I'm so fasinated with HVAC in these cars!

I have a picture of what was on my 83 SC, it had A/C (not working) but the PO "fixed" the system to blow air at least hope this helps http://forums.pelicanparts.com/uploa...1142731759.jpg

Thats an interesting attachment that you are showing. I had to sit and think about why the additional butterfly valve was required. It appears that it was an attempt to regulate the amount of fresh air flowing thru the center vent. I still see a problem if you like to mix fresh air with heat, like I sometimes do. The way things are plumbed if you add some fresh air to you heated air you will get the mix in the defrost vents and/or the under dash vents but you will get only fresh air from the center vent. I guess you would then need to close the vanes on the center vent to prevent air flow. Damn, I love this system. It does look like they got it right with the 964.