Modern AC

[Bruce Rudin]

I am interested in way more functional AC for my 280 SL. The car is completely apart for a rotisserie restoration. It seems that most of the AC conversions or retrofits keep the stock heater core and blower motor/switch, none of which are all that efficient compared to modern cars. So ending up with multiple blowers, heater core etc. seems redundant. Has anyone looked at deleting all of that and going with a more modern unit like vintage air produces?  They easily combine heat and AC. The blowers are way more powerful and quieter. They have ducting for the defrosters (dehumidified defrost air!) and the ability to duct to the dash vents as well as a much smaller and better looking central vent in the middle of the car and not over the passenger footwell.  has anyone done this type of conversion?  There is actually a lot of room behind the central part of the dash.  It likely will require a remote panel for heat and AC controls. Console? Glove box? I am going to start laying out the components and see what is necessary and possible.  The cockpit is so small that the unit is actually one of the small units that they make, and with the 50 year newer technology and efficiency I believe that this is worth the effort.
The modern installs are so ugly. Getting air to the dash vents will make it feel way cooler than blowing on your waist.

[clunker]

You are not wrong that a better approach may be to replace the whole HVAC system with a more compact, efficient modern version - ensuring mostly reversible of course. The standard bolt on AC (imperial fittings and all) maybe be the original order option, but hardly part of the original design. I too feel the way may be to take out the whole central blower/heater core and use the freed up space for a combined unit. The existing mechanical levers/cables could repurpose to operate the new electronic control unit; only a simply AC on/off switch by ashtray need - or convert the exiting fan control to turn plus pull on/off.

I managed to route some ducting to each end of the dash vents (see couple of pics attached - I think one from Naj) as a test and that may permit air delivery pretty much on an unchanged dash.

The HVAC unit I think may be a good candidate is the Bantam by Restomod Air (install pdf attached) - though the Vintage Air Gen II Mini or ComPac may also work, and they have reasonable price mockup units available.

But for now this is a just thought project for me.

[Bruce Rudin]

The biggest impediment that I see is the radio. I am not terribly bothered by hanging the radio below the dash like on my Speedster. That seems to be the worst case scenario and clearly reversible.  The radio slot might end up provided clearance for the unit or dash level ductwork. Thanks for the mock up info. I will try the vintage air units for gross placement.  They also vent into the foot wells so all the supplies mimic a modern car.

[doitwright]

I have made mention of doing what you are talking about in other posts and am already very deep into the development of an integrated heat/AC system with several hundred hours already spent. My design will utilize the existing dash vents and have 2 additional center vents centered below the radio. I am using the core of the Vintage Air Gen II mini. The Vintage Air system has a very nice core that combines the heater core and evaporator as one core with half being evaporator and half heater? I have designed an evaporator/heater core housing based on modifications to the Vintage Air housing in order to fit the space available in the W113. The entire original heater/air distribution system will be replaced but there will be not cutting or alterations to the W113 chassis. I am fabricating molds and creating vacuum formed parts from sheets of ABS. There will be a modified version of the defroster ducts and ductwork fitted to the rear of the original dash vents. My controls will utilize the existing W113 heater levers that are adapted to control the servo motors that control air distribution, AC temperature and Heat temperature. The center vents will fit into an outer trim that is inspired by the AC used in the later model W111 coupes and cabriolets. A few additional features will be included in the design such as an automatic heater core bypass and replaceable cabin filter.

The main obstacle I have encountered which requires continuous test fits is the wiper linkage. As the wipers move, the linkage rods behind the heater levers get very close to the frame. I have a bolt-on frame to the heater lever frame that allows me to mount.

I have not been able to work on this project since December due to a remodeling job I have to get finished by May 1. Once I get it completed and tested I plan to post a recap of the project and post my results.

[clunker]

Re: removal of radio: maybe  you can see on my profile pic that I removed the (aftermarket) radio and restored the blanking plate. I repurposed the cigar lighter (a reversible mod) to be the on/off volume for a bluetooth receiver/amp - you cannot see anything different. I put the mic snug in front of the ashtray so it also out of sight. It simple but effective, phone and spotify work fine.

[Bruce Rudin]

I am happy to pool resources to move this project along, both monetarily and/or taking some of the work off your plate.  I can work on the center vent system perhaps? Perhaps of you think this idea has merit, please call or email directly
brucerudin@comcast.net
302 584-2412

[Martyberg]

I’m thinking of installing this  “MiniKool” a/c. It fits under the dash and takes away very little from the passenger legroom. I would probably run an outlet to each fresh air vent and the third in the footwell area. The unit is very compact, I cut out a box the same dimensions and it fits comfortably. Any thoughts on this?

[doitwright]

Martyberg

Interesting possibility. Have you thought about how you will connect the duct to the dash vent? Directing a pipe to the foot well may not be ideal since for AC you will get the best cooling by directing the airflow up high in the cabin. Have you checked the cooling capacity of the unit in relation to the cabin volume?

[Martyberg]

Still early stages but a possibility for the 3rd outlet is to direct it up through the speaker grill as I don’t have a speaker there. I’ll get hold of the company and see what the cooling capacity is. This would be a big project for me so I need to make sure I really want to do this before I pull the trigger!

[jeblack123]

Does anyone have pictures and/or part numbers for the W108/111 sedan compressor bracket and thermostat housing with the elongated neck for installation of a compressor in the upper position?

Thank you for looking.

James

[clunker]

Thermostat top cover/high neck 1292030174 1292030374 1292030474

Sedan AC Compressor Bracket 1081300235 **correction

You may also need to remove the banjo fitting at front of lower housing. The flow from there needs to be instead taken off the lower side hose, by inserting the Y-connector 1142000184 (which was used in later W113 anyway I think)

[jeblack123]

Great. Thanks for the info!

James

[clunker]

Apologies I typo'ed the wrong part there - have edited the original post to correct it.

The part I listed is the lower alternator mount bracket 1301550035 - you only need this this to mount the alternator at lower position if was not already down there (ie due to a previous MB AC install.

[Bruce Rudin]

Curious if you have made any progress on the AC conversion.  Looking to be your first customer or test site.

[Mpgeslak]

I am in the same position:   Dash totally apart and thinking whether it makes sense to restore the heating components I have or retro-fit a more modern heating and AC unit.    Would happily contribute if the project has moved ahead!

Michael

[clunker]

Michael - you are way ahead given you have the dash apart - I not ready to decommission my car for an extend period just yet!

I still think the best option is to replace the heater core/blower box with an integrated unit - I been looking at either
- the RestoMod Bantam S unit 10.75"x7.5"x17.5" (https://www.restomodair.com/shopproducts/bantam-s-ultra-compact-custom-air-conditioning-system/)
- or the VintageAir Gen II Mini unit 7.3"x9"x19" (https://www.vintageair.com/university/gen-ii-compac-mini-universal-fit-systems/).

The Bantam is pricier than the Gen II, but looks pretty robust, plus has a more flexible mount bracket system. That RestoMod system also has a clean through wall hose connector option.

I have not confirmed these units fit, as I have not (as yet) disassembled my dash! so one needs to look in detail at specs/install etc. (btw VintageAir does sell a cheap plastic mockup).

Either unit would replace the whole existing heater core and blower/air guide box, and so leave decent amount of space to work with. It could look virtually unseen from the original non-ac car by retaining the existing heater controls to actuate potentiometers, etc and recommissioning the fan switch.

I had originally considered an add-on separate ac, like the orig MB add-on unit approach, but much more compact- but it still just seems super inefficient to duplicate the blower and ducting and to take footwell space. I prefer no ac at all in that case!

Together with repurposing of the existing dash-end hidden vent flaps to toggle between heat/cool and fresh (see post further up), the system would look pretty much like a (clean) non ac car. You can add virtually invisible central vents that could drop under central dash. I note a replacement modern heat/ac blower unit will also be more powerful and should be better able move sufficient air through the necessarily compact, dash-end ducting.

[Mpgeslak]

Hi Charles,

I have the dash apart to do the interior, but everywhere I look I figure now is the time to fix things as I never want to take it all out again!!
My biggest question is where and how to mount the unit.

Michael

[doitwright]

I have been working on an integrated system for some time. There are numerous logistics to figure out.

Here are a few insights on the progress I have made so far:

I started with a VintageAir Gen II mini and have since moved up to the Gen II super due to it having a larger evaporator/heater core. I can tell you that while there is room for both of these to fit in the space of the stock ventilation/heater core, the configuration of the outlets and connections for coolant/refrigeration lines are not conveniently placed.

I am on my 3rd design right now and feel I am getting closer to what will work.

My design goals from the beginning were:

No cutting any metal on the car.

Utilize existing dash vents.

Add a center vent following design from other Mercedes of the era to give more even cooling as with a modern car. The W111 and W108’s were available with factory air which had vents centered on the lower part of the dash. My design will be a hybrid of those 2 series of cars. I originally thought round vents that match the existing dash vents would be the way to go but they just do not look right in the center of the dash. Later 107’s that came with factory air had round vents but they were located on the upper part of the dash so following that design is not an option.

The system has to fit and function as if the car were designed to have A/C.

Include a cabin filter.

Address the higher operating temperature of the engine on later 280SL’s

The challenges I have faced include:

After determining that the evaporator housing of the stock VintageAir system would not allow me to achieve my goals, I decided to design a new housing. The functionality of how the VintageAir unit operates with its servo motors and dampers to direct air will be utilized. Now I get into educating myself on how to vacuum form ABS. Lots of trial and error here.

The VintageAir Gen II core is one core with internal tubing divided into 2 sections for heat and the A/C evaporator. The VA system also includes a small circuit board that interfaces between the controls and the servo motors.

My original plan was to integrate the existing dash controls with the potentiometers and the A/C compressor control. More challenges here. Mainly with the wiper linkage clearance and having to fit the capillary tube from the A/C compressor control into the evaporator core. I have since decided to go with a automatic climate control system made by Dakota Digital for the Gen II.

The VA system uses 2” and 2-1/2” flex duct to supply air to the defroster ducts and A/C vents. In my design, I plan to utilize the original defroster ducts and supply air to the side vents through the fresh air tunnel.

Using the VA core, I find that having the connections on the right side of the transmission tunnel better suited from an install standpoint. Now if I had a right hand drive car, this would not be the case because it seems it would be better to have these on the passenger side rather than the drivers side. Getting the core connections to the right side requires flipping the stock VA core orientation 180 degrees. This means rather than having the core hose connections on the top left side, they are now on the bottom right side. Easier to properly torque A/C line fittings in this location.

I fabricate my housing using MDF to build a plug. Plugs have to be designed to include considerations on how to removed the plug from the formed part after the vacuum forming process. Indentations in the plug can potentially lock the formed ABS around the plug.

That is kind of it in a nutshell. I am also curious to hear about any progress anyone else is making in this area.

[clunker]

That is a lot of progress and useful information Frank, bravo. When you say you rotated the VA GEN II Super 180 degrees did you mean the outlets now point down and the unit inverted? Does the attached diag describe that orientation accurately? I assume these units not sensitive to being inverted.

I would add to my post, that RestoMod does also do a mock-up box for the Bantam. Their Cyclone unit (which is AC only I believe) does have a reverse/RHD version (and mockup box).

[doitwright]

The upper photo in your attachment is what you would expect to see the normal orientation of the VA Gen II Super. There is a condensate drain centered (not visible in your photo) on the bottom of the housing. Installing the unit as shown in the top photo puts the core connections on the driver side of a LHD W113 and would also set them in the upper area of the cars ventilation compartment where the factory heater core is located.

The orientation of the core in the lower photo makes hose connections more practical but cannot be installed this way using the VA outer housing. This is what makes fabricating a revised housing necessary.

[Mpgeslak]

I may have this wrong but doesn’t the Gen II mini put the connections on the lower right side as desired, see attached?

Michael

[doitwright]

I may have this wrong but doesn’t the Gen II mini put the connections on the lower right side as desired, see attached?

Michael

It depends on how you prefer to orient the unit. In my design, having the A/C supply ports to the rear (engine side) and the defrost vents to the front (cabin side) works best. There is a damper in the housing that directs the air to these two directions. In my design I also relocate the fan to allow an enclosure for a cabin filter. The Gen II mini and Gen II Compac use the same size evaporator/heater core. The Gen II Super is 25-30% larger. According to Vintage Air, the Gen II mini is adequate for small pickup trucks, the Compac for Coupes and small Sedans and the Super is for large sedans. Their site does not make recommendations for convertibles. Taking the evaporator core size of the W113 successor the R107 as a reference, The Gen II Super seems a logical choice. I am sure there is a way to take the Gen II and mount it in place and run the flex duct to your supply vents. However my intended approach is to make a system that is taylor made for the W113 and appears as if Mercedes designed it for the car originally.

[Bruce Rudin]

Wondering if you have made any progress on your modern AC system

[Bruce Rudin]

Wondering if Doitwright has made any progress on his modified AC setup?

[Jack the Knife]

I'm certainly hopeful for some progress on this project, as a modern system would be a nice thing to have, not to mention freeing up some space, possibly...