Vent help (Can't shut it off!)

[Grabinov911]

Hey Guys,

I have a 1970 RR with factory air. I am running a Sanden compressor but inside of the car the HVAC unit is totally factory. I don't have the water hoses hooked up for the heater, so I either have AC or "nothing". I don't have any of the vacuum hoses connected in the engine bay and so the HVAC doors don't move around. I can basically just turn the AC compressor on and off and the HVAC fan on and off. Here's where I need help:

Driving the car in the California-cold morning, I'm getting cold outside air through the vents - basically because I'm in "AC mode" all the time - the compressor and fan aren't running because the AC is off, but the doors in the unit are still allowing fresh air in.

Does anyone know which lever on the HVAC unit I need to pull to shut off the air altogether? Basically, what I'm looking for is the factory configuration for no Heat and no AC. I figure I only need to adjust it once in a while, so I'll just crawl under the dash and do it, and then put it back in the other position when I need AC starting in June!

Thanks!

 

[monroegtx]

This is the system off position from the 70 fsm for factory a/c. Hope it helps.

 

[monroegtx]

This one shows the positions of the doors better.

 

[Grabinov911]

Thanks Monroe! From your first post: It looks like I need the Fresh Air Recirculating Door closed and in the Recirculating position. Interestingly, that would also put the system in the Max AC position, which will probably work for my AC needs as well in most circumstances.

 

[Grabinov911]

Well with the quick response from Monroe (on a California Saturday night with an answer from Australia - Wait. Isn't there a Melbourne, Florida too?) I was able to get to solving the problem. The original problem took about 30 seconds. The Recirculation/Fresh Air door is at about the easiest spot to manage on the air box - right in the passenger footwell. I just pushed it into the "Recirc" position. The air intake for the fan in that position is from the interior rather than from the cowl. I discovered another problem at the same time though.

The ducting from the cowl to the Recirc/Fresh Air "box" is nearly torn away from the frame which attaches it to the underside of the cowl/firewall area.

The problem with the torn duct is that the cowl air puts positive pressure on the air box. That means that even with the Fresh Air door closed, the incoming air will reach the cabin through the torn duct. While that's not as bad as having it blow into my face through the vent, it's still not exactly ideal. There is A LOT of air which comes through there.

I pulled the frame (shown in the last pic) out and am cleaning that up. Now I need to see if I can source a replacement duct. I was able to cut away the tear but the entire duct is starting to go. Might as well at least try to replace it...

 

[kiwigtx]

Time for a rebuild by the looks of that heater box.

 

[kiwigtx]

@Grabinov911 ...you need to have a good read of Glenn's build thread. There is a lot of detail and some great pictures from his build a few years ago.
https://www.forbbodiesonly.com/moparforum/threads/monroes-70-gtx.30760/

It's an awesome '70 GTX and I have seen it in the flesh.

I met this guy a few hours earlier...

Great memories from an outstanding flying visit.

 

[Grabinov911]

After cutting away the completely ruined section of the Fresh Air duct I used black cloth and contact cement to create patches for the torn section and seal up the tears. For anyone who tries this repair, be advised: The duct is BARELY long enough as it is. If, like me, you lose about 1/2" of it to an initial tear (which is what caused you to do the job in the first place), you'll find that it is pretty tough to get the duct to reach and make the 90 degree turn you need. I thought about simply replacing the duct with something made from a home-depot duct (or similar), but the factory duct is square on one end and oval on the other! Try find something that is the right diameter and can be made to do that!

I was able to get everything cleaned up, repainted and replaced using the factory "J hooks" that hold the air duct frame to the cowl/dash. These just dropped out when I removed the frame in the first place or I never would have known they were there. BTW, looking online, these parts, if you can find them at all, look like they're EXPENSIVE, so be careful. I saw a replacement "restored" part (with the two end frames and the duct) for $335.00! Now for a test drive...