Retrofitting non-A/C ventilation ducts

[stormcrow]

I have completely eliminated the outside air vent when I removed the blower assebly. The way the system works is the blower return pulls air in from the cabin and recircs it. The temperature controller for the A/C controls the air temp in the cabin.

Now if I want heat, I pull up the levers between the seats and get the hot air. I can also run the AC at the same time.

The hoses shown go to the dash louver in the center of the dash, and to the connector on each side.

I used "2" vacuume hose and 2" pvc fittings along with a 2X1 1/2 reducer that connects directly to the fitting on the vehicle. I used a 4" tee with a 3" coupling inserted in the tee to raise it up.

With regard to my motor, I purchased a 3 speed 12V motor and installed a plate to mount the motor to. I went to the junk yard and got a fan/blower assembly off a chevy and mounted it inside the housing.

I had to remove the fingers that held the original motor in place, and had to raise the housing so the blower wheel wouldn't rub.

Anyway, I get a lot more air flow primarily because the blower wheel is not restricted with the motor in it, and the reducers at the connections increase the velocity to push the air faster through the duct.

I am also looking into putting another vent on the far passenger side similar to the 83's and one on the drivers side.

Hope this info helps.

SteveKJR

[javadog]

Originally Posted by frankc

So did the A/C blower supply cool air to only the center vent in the brown car (before you removed it)?

You know, I don't remember. Yanking the A/C components is one of the first things that was done to the car when I bought it and I don't recall if I ever ran the A/C. I do know that we didn't change the distirbution boxes though.

JR

[EPorsche]

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[Vin-barrett]

I did complete this project and i recommend to others. It's very easy to do I just wish I had done it years ago...

I used my existing distribution boxes with the part #20 like the white car in the thread has. Nice to have the air through the middle vent.

[SiberianDVM]

I took a slightly different route:

I deleted the A/C, including the evaporator coil, but kept the smugler's box fan. I added a PVC conector on the fan box, running a 3" flex duct up to where the front condenser was beore the delete. There I connected the duct to a NACA duct.

The 3 way fan switch is mounted in the dash.

[kens_74_911s]

stormcrow

The center vent will take in water when driving in rain and best i can tell is the drain point for the upper hood edge weatherstripping . what did you do to route that water? Make a special catch pan with drain? I could not see it in your pictures. I looked at your post quick since I need to run out but will study this closer. My 74 does not have air yet . I do remember one of my other 911 cars had air removed and there was a crude cutout into passengers Ft footwell . Is that where you are getting your un "fresh air"?
Ken

[stormcrow]

Ken,

When I removed the blower I cut some "grey smoked lexan" to fit as an exact match as the screen that was there.

If youtake the screen to a auto window shop they can cut it for you - it's a lot harder then you think to try and do it yourself.

I also placed my V-1 radar detector behind it in the center of the vehicle - I had to do a little sheet metal work but it fits great - have a "remote" display in the ashtray. Included a remote switch on the left side just below the key to turn it off in an emergency.

It works great when going through VA - they can't detect the V-1 and should they come up on you you can close the ash tray.

I believe I posted some pics on the site several years ago.

[kens_74_911s]

Okay get it nothing passes through. I need to look closer but I t looks like the hood seal in that area dips down and will collect water so your seal is so tight you don't get anything though and it just builds up until it exits at ends and runs down the hood side seals?

[ganun]

I`ve been following this since I went thru some of it with my 87....I must warn you all, this is a disease that gnaws at your brain in the middle of the night and sucks your time .....the question is is it worth it, I ended up removing the heater and upgrading the A/C...period. IMO the whole HVAC system in this vintage is worthless. As an example, the evap draws air not just from behind the wood footrest but also from the remenant hole into the center tunnel. Why?? no funds , time, interest to fix it. I considered removing everything and starting from scratch by designing a modern single blower sytem. Then reason prevailed and just said what the guys at the factory probably said POS .....

[kens_74_911s]

Okay I feel a little better now knowing that I am not the only one that feels that way about the climate controls in the early cars. I am on my 5th 911 now (all early cars). The system is basic and a little rough. Take it to the next extreme my 92 BMW 735il has 7 or so servos controlling all the flaps and vents split heater AC core etc. over complex liking to dumb it down dealing with both ends of the solution.

My 911 mods may be a balancing act. I do have two early 944 condenser/blower assemblies and one complete heater AC box with fan out of my 528 bmw and a stock early 911 unit to evaluate. I suspect cutting out the dash area behind glove box or cutting down glove box area may be necessary, more later.
K

[Craig_D]

Ken, it would sure be interesting to see a servo/electronic upgrade for the 911's levers, and push/pull wires system (which mine are bent at the lever and I need to replace them all...).

[stormcrow]

Ken,

Here's the link to where I installed my V! and removed the outside air vent - as you can see by the pics, I replaced the screen of the outside air vent with smoked lexan

http://forums.pelicanparts.com/porsche-911-technical-forum/406884-stealth-v.html

[frankc]

Originally Posted by Craig_D

Ken, it would sure be interesting to see a servo/electronic upgrade for the 911's levers, and push/pull wires system (which mine are bent at the lever and I need to replace them all...).

Hey Craig,
Nice to see you over here .

I will be replacing the entire ventilation lever control system with a non-A/C part when I get my car back from the body shop, and will document the procedure here for those interested.

[Craig_D]

Originally Posted by frankc

Hey Craig,
Nice to see you over here .

I will be replacing the entire ventilation lever control system with a non-A/C part when I get my car back from the body shop, and will document the procedure here for those interested.

Hi Frank, I'll watch with keen interest as I think that these old systems could work much better with some new tech componentry.

Oh, and your suspension rebuild looks very very thorough! I hope all goes well in the paint shop.

Cheers, - Craig

[quattrorunner]

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[wgirardot]

Originally Posted by kens_74_911s

Okay I feel a little better now knowing that I am not the only one that feels that way about the climate controls in the early cars. I am on my 5th 911 now (all early cars). The system is basic and a little rough. Take it to the next extreme my 92 BMW 735il has 7 or so servos controlling all the flaps and vents split heater AC core etc. over complex liking to dumb it down dealing with both ends of the solution.

My 911 mods may be a balancing act. I do have two early 944 condenser/blower assemblies and one complete heater AC box with fan out of my 528 bmw and a stock early 911 unit to evaluate. I suspect cutting out the dash area behind glove box or cutting down glove box area may be necessary, more later.
K

the key priority (*in my opinion) is to have an upgraded a/c sytem that blows cold, and maintains a charge.
following that is is a backdated heat system. Third is the fresh air system (with or without motor plugged in). Using the levers and controls you can dial in any climate you want (using a conbination of 1,2,3). With proper a/c it is a good system. You just have to learn how the different controls and levers work.

just my .02


Bill

Bill

[frankc]

Ok, time for an update on this project - I'll start with showing how I swapped out the A/C version of the ventilation controls in the dash (three levers) with the non-A/C version (four levers). I actually did this swap several weeks ago, but I'm just now getting a chance to post. Also, in case it was not obvious, these instruction are for a LHD vehicle. I'm not sure how symmetrical the LHD and RHD cars are, so if you have a RHD car, these instructions may not help you all that much.

The first step in removing the control levers is to unplug its wiring harness. Believe it or not, to do that we start by removing the right side dash knee pad below the glove box - and here's the reason. Take a look at the Photo 1 and notice the wiring harness attached to the control. As you would suspect, most of those wires go to the fan to control the fan speed, but the longest wire runs over to the glove box light switch. What is the glove box light wiring doing mixed in with the fan speed harness? My theory on this "logic" is that the switch is on the inside of the cabin, and the light is in the trunk. The factory needed some way of passing the ground wire from the switch through the front bulkhead to the light in the trunk, and there was an available pin on the connector for the fan speed harness that connects the harness from the controls (in the cabin) to the fan motor (in the trunk), so they piggybacked the wire for the glove box switch on that connector for the bulkhead pass-through.

Photo 1:



Here's where it gets interesting. In order to get access to the glove box light switch, we need to remove the glove box itself, which is held in by a strap on the bottom. The screw holding the strap is accessible behind the glove box door. But you will soon discover that the glove box door will not hinge down far enough to access the screw because the knee pad is in the way - thus the reason for removing the knee pad . I sure hope all this was by design.

So here it goes.


Phase 1: Disconnecting the wiring harness

Step 0: Disconnect battery (hopefully this should be obvious since we are working on the wiring)

Step 1: Remove right side dash knee pad. The knee pad is held on by two nuts behind the lower dash (Photos 2 & 3). Some folks have complained that these nuts were very tight on their cars, but mine came off without any issues.

Photo 2:


Photo 3:



Step 2: Open glove box door and let it hang vertical. Remove glove box contents. Remove middle screw at base of door (Photo 4). This will allow the strap holding the glove box to be released (Photo 5).

Photo 4:


Photo 5:



Step 3: Go under the dash, lower the strap and remove the glove box by simply pulling it away from the door. There may be some wires you need to move out of the way. No photos here, but it should be obvious.


Step 4: Look to the right in the glove box door opening and you should now see the light switch connection (Photo 6). Unplug the wire from the switch.

Photo 6:



Step 5: Unplug the connector on the bulkhead going into the trunk (Photo 7).

Photo 7:



The harness should now be free. There is a separate ground wire attached to the control which we will get to later. In my car the harness was coiled up and bundled with the radio wires behind the radio, so you may need to undo that mess to free the harness.

That's it for tonight. I'll continue with removing the actual control levers tomorrow.

Cheers,
Frank

[javadog]

"I know some people refer to the metal panel separating the cabin from the front trunk as the firewall even on a 911, but that doesn't seem right (the firewall is behind the rear seats), so I'm not sure what term to use here (any suggestions?)"

You can call it a bulkhead.

JR

[Vin-barrett]

Thank you Frank, Great post. I'll be doing this too... watching this thread

[frankc]

Originally Posted by javadog

"I know some people refer to the metal panel separating the cabin from the front trunk as the firewall even on a 911, but that doesn't seem right (the firewall is behind the rear seats), so I'm not sure what term to use here (any suggestions?)"

You can call it a bulkhead.

JR

Thank you JR - that's the word I was searching for. I'll go back and edit my post to add clarity.