Air Conditioning, Evaporator solutions Options

[mepstein]

The key thing is getting all this to fit inside the fresh air Behr box. If you can find a small enough coil, very little modification would be necessary. The better route is to make a custom box to fit a standard off the shelf evap coil and possible a heater core for the water pumpers. It would be cool to 3d print a new box, or use plastic vacuum forming to create two clam shells that snap together.

When making a new box, the question is, do you run outside air across the evap coil, or do you have provisions to bring in return air from the cabin, essentially blocking off the cowl vents?

Tim - I'm just going to fly you out and start writing checks when it's time to do my suby a/c. Not even worth me tying to understand the a/c thing let alone work out a solution.

[timothy_nd28]

would you be willing to write a check for a metal 3d printer? (IMG:style_emoticons/default/santa_smiley.gif)

[mepstein]

would you be willing to write a check for a metal 3d printer? (IMG:style_emoticons/default/santa_smiley.gif)

I have a feeling they are pricey?

[ssuperflyoldguy]

The key thing is getting all this to fit inside the fresh air Behr box. If you can find a small enough coil, very little modification would be necessary. The better route is to make a custom box to fit a standard off the shelf evap coil and possible a heater core for the water pumpers. It would be cool to 3d print a new box, or use plastic vacuum forming to create two clam shells that snap together.

When making a new box, the question is, do you run outside air across the evap coil, or do you have provisions to bring in return air from the cabin, essentially blocking off the cowl vents?

I'm on a small refrigeration project right now that uses really small stuff, custom sized evaps are doable but better to find one the right size, it seems that the mass produced ones are more dense in cooling area there fore more efficient. 2 - ways build the box with good fans, find the coils or find coils & fans that are cheap, easy n plentiful and build box around them.

How about AC system in either trunk and duct conditioned air into cab?

[dlee6204]

The key thing is getting all this to fit inside the fresh air Behr box. If you can find a small enough coil, very little modification would be necessary. The better route is to make a custom box to fit a standard off the shelf evap coil and possible a heater core for the water pumpers. It would be cool to 3d print a new box, or use plastic vacuum forming to create two clam shells that snap together.

When making a new box, the question is, do you run outside air across the evap coil, or do you have provisions to bring in return air from the cabin, essentially blocking off the cowl vents?

I think trying to modify the Behr box would be a huge compromise and I highly doubt the wimpy fan in there would deliver the required amount of air across the core.

I also think a recirculating system is the only way to go.

I too have the desire to build my own Evaporator box under the cowl but it's a project on a list of projects. Plus I moved to an area where I no longer need AC.

[Chris914n6]

I have to chuckle at these last few posts. Everything you guys talked about I've already done. I just need to test it and possibly make a few tweaks before committing a few grand to importing custom cores and materials. Plus I need a window of time. I even built a vacuum forming machine so I can control the quality.
I've also worked out an engine lid mount condenser.
It's a well thought out system, I just don't brag much.

[Mowog4]

I have to chuckle at these last few posts. Everything you guys talked about I've already done. I just need to test it and possibly make a few tweaks before committing a few grand to importing custom cores and materials. Plus I need a window of time. I even built a vacuum forming machine so I can control the quality.
I've also worked out an engine lid mount condenser.
It's a well thought out system, I just don't brag much.

I would like to have something functioning in weeks, if you have AC and heat, it fits and works, I will take one. Since I am using the subie I am ok with the condenser and compressor.

[timothy_nd28]

Chris, I'm losing faith in your project. It's been 2 years since you first posted about this potential stock looking AC solution. I also question the use of custom made evaporator coils. If you are in the industry, you should then know that these coils will eventually develop a leak. When this does happen, how does one obtain a new replacement coil? Custom work is expensive especially for one off replacement parts.
You're going through all this trouble of making a new fresh air box, why not use a standard "off the shelf" small evaporator coil, which will be available for years to come? There must be some car out there, ie, Ford Fiesta or something that has a coil which you can design this new box around? Unless you are doing this on purpose thus making all of this proprietary?

[76-914]

There are probably 3 or 4 members that could or can make a working model. But, and it is a Big But, anything AC for a 914 is a Fringe Market. I'd bet if Chris develops & sells these he will never recoup his investment. And if he wanted to make money off these; forget it. Probably would be better off taking a 2nd job at a 7-11. I probably had 60+ hours installing an under dash unit and modifying the defrost/vent system for it. Chris will have that much time tied up just removing the damned old air box. (IMG:style_emoticons/default/av-943.gif) Well, that's an exaggeration but you get the idea. He's also been around long enough to see how many people express an interest in a product only to never order it. I for one am guilty of this. (IMG:style_emoticons/default/rolleyes.gif) Others have said this but it bares repeating. Be supportive of those that "do" provide us our 914 products and appreciative of those trying. And finally just to (IMG:style_emoticons/default/stirthepot.gif) the (IMG:style_emoticons/default/stromberg.gif) ; look back and you'll find this subject pops up this time of year and dies down 2-3 months later. Peace out my brothers. (IMG:style_emoticons/default/beerchug.gif) KWoody

[Mowog4]

There are probably 3 or 4 members that could or can make a working model. But, and it is a Big But, anything AC for a 914 is a Fringe Market. I'd bet if Chris develops & sells these he will never recoup his investment. And if he wanted to make money off these; forget it. Probably would be better off taking a 2nd job at a 7-11. I probably had 60+ hours installing an under dash unit and modifying the defrost/vent system for it. Chris will have that much time tied up just removing the damned old air box. (IMG:style_emoticons/default/av-943.gif) Well, that's an exaggeration but you get the idea. He's also been around long enough to see how many people express an interest in a product only to never order it. I for one am guilty of this. (IMG:style_emoticons/default/rolleyes.gif) Others have said this but it bares repeating. Be supportive of those that "do" provide us our 914 products and appreciative of those trying. And finally just to (IMG:style_emoticons/default/stirthepot.gif) the (IMG:style_emoticons/default/stromberg.gif) ; look back and you'll find this subject pops up this time of year and dies down 2-3 months later. Peace out my brothers. (IMG:style_emoticons/default/beerchug.gif) KWoody

You are absolutely correct, I am just too stupid to take the advice and will forge ahead. Luckily I am not looking to sell a product, I just want a 914 as a daily driver. If I can make it work, I will document it and anyone else interested in it can improve upon it and make the world a better place for at least ten of us (IMG:style_emoticons/default/smile.gif)

I have played with British cars for years, I can't imagine trying to generate an income from this hobby. For some reason I am willing to do a ton of work, spend stupid money, have hours of frustration for something only I care about. I assume I was dropped on my head as a child.

[914_teener]

The key thing is getting all this to fit inside the fresh air Behr box. If you can find a small enough coil, very little modification would be necessary. The better route is to make a custom box to fit a standard off the shelf evap coil and possible a heater core for the water pumpers. It would be cool to 3d print a new box, or use plastic vacuum forming to create two clam shells that snap together.

When making a new box, the question is, do you run outside air across the evap coil, or do you have provisions to bring in return air from the cabin, essentially blocking off the cowl vents?

I think trying to modify the Behr box would be a huge compromise and I highly doubt the wimpy fan in there would deliver the required amount of air across the core.

I also think a recirculating system is the only way to go.

I too have the desire to build my own Evaporator box under the cowl but it's a project on a list of projects. Plus I moved to an area where I no longer need AC.

(IMG:style_emoticons/default/agree.gif)

Then the problem will be what about humid areas.

I wouldn.the take this on unless I was retired.....not a nay sayer....just plenty of white fences to paint on someone else accord..

[Chris914n6]

You're going through all this trouble of making a new fresh air box, why not use a standard "off the shelf" small evaporator coil, which will be available for years to come? There must be some car out there, ie, Ford Fiesta or something that has a coil which you can design this new box around? Unless you are doing this on purpose thus making all of this proprietary?

Trust me, it's not custom on purpose. I have catalogs. MR2, Miata, Mini, all wrong shape. I have not seen an evaporator that fit within the 6" limit between the wiper motor and gas tank and the up/down limit with airflow, and that's even with the option of trimming inlets. Plus the core has to work with the various compressors being used. Too little and it freezes every minute.
The cores are not that pricey if you skip the American middleman. I have to buy at least 50 and maybe a few more depending on actual commitments, so there will be a few spares. But in the 20 years I've been a mechanic in Vegas I have yet to see a failed evap.

Mowog4- If I ordered components today it would still take a many weeks for cores to get made and sail over here, so I won't have it in your time frame.

[timothy_nd28]

I have a friend that owns a small automotive repair shop, he does at least 3 evaporator coils a month. Dodge seems to be more prevalent with these failures. I replaced one in my Durango a few years ago, cracked the damn windshield when pulling the dash while trying to get to this coil. Wife's minivan developed a leak in the rear evaporator coil last month. I even replaced a evaporator coil last night at Garolds house because it too was a leaker. Either from cost savings or perhaps better transfer rates, the wall thickness of these coils are thinner than what they used to be and will fail over time due to stress of pressure cycling or driving over some hellacious pot hole.

I didn't know you tried other coils. A few months before you conducted your poll, I talked with a guy who did conversions for older cars, and had done this conversion for the 914. He sent me pictures of the modified fresh air box, and I'm pretty sure I deleted the emails and for the life of me, I can't remember what model car he used the evaporator coil from. Even though he stuffed a coil into the fresh air box, there was no additional room for a heater core.

I'm not following the freezing issue. Two things that I can think of that causes a evap coil to freeze would be low charge and or low airflow across the evaporator coil. Overcharging will not cause this issue, because refrigerant has a proportional pressure to temperature relationship. Higher pressure (more freon) equals a higher saturation temperatures.

You will need to meet the minimum CFM across the evap coil.
Low airflow across the evap coil is something you may battle. You will also need to size the compressor, preferably the smallest displacement one Sanden sells.
To protect this compressor with low airflow across the evap coil, I would strongly recommend installing a suction line accumulator. This will protect the compressor by keeping everything in vapor state which will save the compressor from trying to compress a liquid. Installing a smart metering device, TXV valve will also help with low airflow, by throttling back refrigerant flow based on coil temperature.

I'm cheering for you, and anybody else willing to solve this problem. I may come off as pretentious, and I'm sorry for that. I'm overly anxious with this project and would love to see some resolution or atleast some tiny light at the end of the tunnel.

[amfab]

My car came with a/c and I replaced the compressor with a rotary Sanden. I built a frame around the condensor with 1/2" tubing and expanded metal mesh to clean up the installation. My evaporator could be used but I have been trying to figure out something that looks better. I bought the unit in the photos below thinking I could run hoses to the factory vents. The problem is that even as shallow as the evaporator is it's pretty impossible to hide it. If you try to mount it in the center of the dash the u-joint for the steering is in the way. The factory aftermarket unit is offset with the motor on the passenger side so that it clears the u-joint.

Hi Mark,

Would the entire unit fit on the passenger side and allow a hose to be run across to the driver side?

By your measurements it should fit—just hang down about an inch and a half below (but behind) the lower dashpad.

Oldair has another version of that unit with two vents in the front and two on the sides.

-Andrew

[mgp4591]

BIGKAT 83 designed and installed a Mustang II hybrid a/c system in his blue 914 that worked very well by all accounts. The details are hidden in the archives and are fairly complete in documentation as I remember...

[MoveQik]

You are absolutely correct, I am just too stupid to take the advice and will forge ahead. Luckily I am not looking to sell a product, I just want a 914 as a daily driver. If I can make it work, I will document it and anyone else interested in it can improve upon it and make the world a better place for at least ten of us (IMG:style_emoticons/default/smile.gif)

I have played with British cars for years, I can't imagine trying to generate an income from this hobby. For some reason I am willing to do a ton of work, spend stupid money, have hours of frustration for something only I care about. I assume I was dropped on my head as a child.

I have my car exactly the way I want it with the exception of AC. I would gladly pony up the cash to get it if someone came up with a workable, clean solution. You are local to me so I say go do it!! And then let me stop by and check it out. (IMG:style_emoticons/default/beerchug.gif)

[Mowog4]

You are absolutely correct, I am just too stupid to take the advice and will forge ahead. Luckily I am not looking to sell a product, I just want a 914 as a daily driver. If I can make it work, I will document it and anyone else interested in it can improve upon it and make the world a better place for at least ten of us (IMG:style_emoticons/default/smile.gif)

I have played with British cars for years, I can't imagine trying to generate an income from this hobby. For some reason I am willing to do a ton of work, spend stupid money, have hours of frustration for something only I care about. I assume I was dropped on my head as a child.

I have my car exactly the way I want it with the exception of AC. I would gladly pony up the cash to get it if someone came up with a workable, clean solution. You are local to me so I say go do it!! And then let me stop by and check it out. (IMG:style_emoticons/default/beerchug.gif)

I am making some progress, although life sometimes is getting in the way. My current plan is an evaporator (probably out of a geo metro) mounted side ways where the Behr Air Box used to go, a big fan mounted to the side of it, blowing into the side vents in my dash. I am working on mixing heat and cold so I have climate control. It certainly will not be period correct, but that went out the window with the Subaru Engine. If you look on line for Porsche 914-6 AC there is a guy named John Lovejoy out of Florida who has done this. I have tried contacting him, but have been unsuccessful. Anyway, I am plugging away. When it is figured it out you are welcome to come by, take a look and I will tell you everything I used.
Ed

[timothy_nd28]

I found the pictures that Jerry West sent to me of his modified air box he used! (IMG:style_emoticons/default/biggrin.gif)



Looks like he grafted in some 4x10x6" endboot used for HVAC duct work.

[Mowog4]

I found the pictures that Jerry West sent to me of his modified air box he used! (IMG:style_emoticons/default/biggrin.gif)



Looks like he grafted in some 4x10x6" endboot used for HVAC duct work.

Thank you for the pics, these will help a lot. I have tried to get a hold of Jerry West, but had no luck. He did the AC system on the 914-6 from Florida.

[timothy_nd28]

Notice the thermostatic expansion valve (TXV) hanging off the side, sometimes referred to as the H block. This is vital for what we are trying to do. The compressor has a certain designed volume of displacement that needs to be maintained. This is typically done by correctly sizing the evaporator coil to the compressor.

Due to size constraints, we are ultimately forced to use a evaporator coil that is smaller than the displacement of the compressor. This is a bad thing, as it simulates a low air across the evaporator coil condition. In this state, the refrigerant doesn't stay in its gaseous state, and the compressor tries to compress a liquid which is physically impossible. This is certain death for any compressor.

TXV valves will help modulate head pressure by sensing the evaporator coils temperature. As the evap coil gets too cold, a internal bypass within the TXV valve opens.
In addition to having a TXV valve installed, you should also have a suction line accumulator as part of the system. The accumulator will help ensure that only refrigerant gas will enter the compressor not liquid.