Doug's A/C System, R&D/Build Thread Options

[friethmiller]

Just to follow-up on my issue from last year... I was able to install a /6-style hand throttle that I purchased from Tangerine Racing. I mainly use it for cold startups but have used it successfully to hold a minimum throttle for when my A/C is running at a traffic light on a very hot Texas day. Unfortunately, my system has a very slow leak and I plan to take it up to have @technicalninja take a look at it. Going to need cold air coming out of my vents down here soon! (IMG:style_emoticons/default/biggrin.gif)

[DRPHIL914]

looking good! some day i would like to have a/c ... gets hot here in SC too, July - september are not tolerated well without AC

[technicalninja]

Looking forward to your visit! (IMG:style_emoticons/default/ninja.gif)

Just quickly ran through your posts...

Goody! Goody! Flat fin multi-pass condenser, good fan, killer compressor, puppy even has a modern evap!

This is pretty much how I would do a top mount.

I'm betting that's COLD even down here when it's 100+

Once again freaking exquisite fabrication!


I have a HP10 leak detector that came with a 'reference' bottle that is a calibrated leak of R11.

You adjust the sensitivity of the detector to the reference leak...

I'm still on my first reference bottle, about 20% of an ounce has leaked out over the last 6 years. I'm on my second detector and probably the fourth sensor element...
These units can find THAT small a leak...

Was the oil died?
Did it look like green Kool-Aid? I call it Shrek blood.
If so, I have a LED UV light that will give you flash blindness if you look at it, even in sunlight.
Die leaks looks like a "fluorescent crime scene" with this light.

You've got a NICE car!
I want to play with it... (IMG:style_emoticons/default/ninja.gif)

[ClayPerrine]

I want one of those compressor mounts for Betty's car. I hate the idea of cutting the engine shelf in a freshly painted engine compartment. (IMG:style_emoticons/default/pinch.gif)

[friethmiller]

Was the oil died?
Did it look like green Kool-Aid?

@technicalninja - I had a guy here locally that had just closed down his Automotive A/C shop during Covid charge my system. Not sure what he did to check for any leaks but I do know he had to add a ground for the evap, which I had forgot to install. Not sure if you noticed on the firewall on my LE, I created another hole just for routing A/C wiring (with the rubber plug). I learned on the red car not to wait till everything else is installed to try and wire in the entire A/C system.

[friethmiller]

Well, last Friday, I set out from Austin, TX driving 160 miles north - heading to Granbury, TX to meet Rick ( @technicalninja ) in person and let him have a look at my 914's A/C system. Rick owns Granbury Auto A/C and had kindly offered to help me out and teach me how to check/service my A/C system. With my A/C blowing warm air, I figured I'd better get up there before things started getting hot here in May. I must mention that the trip up US281 was really nice and would recommend it anytime and in any direction. As soon as I arrived in Granbury, Rick and his wife welcomed me into their shop and immediately went to work diagnosing my A/C. After fixing a few wiring snafus caused by yours truly (IMG:style_emoticons/default/rolleyes.gif), Rick quickly found the leak, cleared and recharged my system, and then showed me how to check the numbers to see how my system was performing. It was interesting to see how poorly my A/C condenser and fan setup performed at idle and how things improved once I was able to move the car at speed. Rick and I discussed a few options for fixing the design of my A/C and I'm sure we has thinking about his current 914 project and how he could improve things on his car. I'm posting this here just as a prelude to some changes I have planned to my condenser/fan setup and a big "THANK YOU" to Rick and his entire family for being so kind and friendly to this complete stranger. Oh, and check out Granbury Auto AC if you need an expert who really knows what he's doing. Bravo! (IMG:style_emoticons/default/first.gif)

[technicalninja]

Fred's visit was interesting for me as well!

Awesome guy who takes DESTROYED 914s and makes them hard to tell it was destroyed.

Very nice car!

The AC system leaves MUCH to be desired...

Needs 3 times the condenser it has in it...

Needs airflow redesign for the condenser...

Needs fans that have serious CFM...

85-degree day and stopped the high side pressure was climbing through 350 with a partial charge!

I reduced the charge even more and kept highs below 325.

55 degree air at idle!

That is a delta V of 30 degrees!

Piss poor!

Running down the road we did see sub 40 air but WOW, this puppy was working HARD to achieve a delta V of 45 degrees.

"Normal" at 85 degrees is low 40s at idle and cycling a bunch at speed off of the thermo probe. Not sure how often it cycled, maybe two or three times during a 10-mile drive. A properly working system would have cycled every 90 seconds (or less) during the same drive,

I advised Fred that I WOULD NOT have allowed the system to leave the shop the way it was running had I installed it!

Possible fixes...

Change system BACK to R12. It's legal to do if the car is a 93 or earlier. This requires full system flushing. I'm not sure this would solve all issues.

Massive redesign of condenser and box. This is the "proper" fix. Dual element condenser with serious fans. I believe the fix should include a forward-facing entrance similar to a GT nose. Might be able to use a smaller opening and not have to cut bumper. Going to research fans like Tygaboy placed in Cairo's car.

The compressor mounting needs improvement as I could see it vibrating pretty seriously at any engine speed below 1500.

Idle electrical power was crappy as well. Needs charging system improvements.

Nice car, nice guy, crappy AC...

I advised NOT to run system stopped at idle. On a hot day it will bounce of the high limit switch and anything above 350 is freaking hard on the equipment.

Condenser box fabrication is in my future...

On a 105 degree day a properly designed system at speed will be bouncing off of the thermo probe and should be able to hit mid 30s for a delta V of 70!

Almost all Toyotas do this. It's possible!

I haven't tested an R12 Toyota for decades, all are R134 now-a-days.

Very best system to date. 2012 BMW X5. This has a control head that has three buttons marked "Eco", "Normal" and "Intense"
The Intense button produced 32.8 degree air at ANY speed (fan or road) including idle for 1/2 hour on a 105 degree day.

It's possible to have 134 air that is COLDER than the old R12 stuff as long as the system is designed properly...

[friethmiller]

Thanks, Rick! Fixing the electrical and compressor mount issues will be easy to do and are first on my list. I'll also look at possibilities for cutting an opening in the valance just below the bumper (just the design for now). Let me know if you figure out the condenser brand/size and a matching high output fan(s). I can create an entirely new box to house it in a more upright or slant position. Sounds like fun to me (IMG:style_emoticons/default/biggrin.gif) Thanks!

[ClayPerrine]

Fred's visit was interesting for me as well!

Awesome guy who takes DESTROYED 914s and makes them hard to tell it was destroyed.

Very nice car!

The AC system leaves MUCH to be desired...

Needs 3 times the condenser it has in it...

Needs airflow redesign for the condenser...

Needs fans that have serious CFM...

85-degree day and stopped the high side pressure was climbing through 350 with a partial charge!

I reduced the charge even more and kept highs below 325.

55 degree air at idle!

That is a delta V of 30 degrees!

Piss poor!

Running down the road we did see sub 40 air but WOW, this puppy was working HARD to achieve a delta V of 45 degrees.

"Normal" at 85 degrees is low 40s at idle and cycling a bunch at speed off of the thermo probe. Not sure how often it cycled, maybe two or three times during a 10-mile drive. A properly working system would have cycled every 90 seconds (or less) during the same drive,

I advised Fred that I WOULD NOT have allowed the system to leave the shop the way it was running had I installed it!

Possible fixes...

Change system BACK to R12. It's legal to do if the car is a 93 or earlier. This requires full system flushing. I'm not sure this would solve all issues.

Massive redesign of condenser and box. This is the "proper" fix. Dual element condenser with serious fans. I believe the fix should include a forward-facing entrance similar to a GT nose. Might be able to use a smaller opening and not have to cut bumper. Going to research fans like Tygaboy placed in Cairo's car.

The compressor mounting needs improvement as I could see it vibrating pretty seriously at any engine speed below 1500.

Idle electrical power was crappy as well. Needs charging system improvements.

Nice car, nice guy, crappy AC...

I advised NOT to run system stopped at idle. On a hot day it will bounce of the high limit switch and anything above 350 is freaking hard on the equipment.

Condenser box fabrication is in my future...

On a 105 degree day a properly designed system at speed will be bouncing off of the thermo probe and should be able to hit mid 30s for a delta V of 70!

Almost all Toyotas do this. It's possible!

I haven't tested an R12 Toyota for decades, all are R134 now-a-days.

Very best system to date. 2012 BMW X5. This has a control head that has three buttons marked "Eco", "Normal" and "Intense"
The Intense button produced 32.8 degree air at ANY speed (fan or road) including idle for 1/2 hour on a 105 degree day.

It's possible to have 134 air that is COLDER than the old R12 stuff as long as the system is designed properly...

This can be fixed without cutting additional holes in the front trunk. Just add a 911 SC condenser between the compressor and the existing condenser, attached to the underside of the engine lid. This condenser by itself is not enough to run the whole system, but it will make an initial drop of the refrigerant temp. Then the original condenser will drop the temp further. By replacing the stock fan on the orignal condenser with a larger aftermarket fan, you can get the AC system cold enough to freeze you out at idle.

I did this on Betty's 914 with the stock DPD system converted to 134a.
It makes it so the engine lid needs a prop stick to stay open, but it works.

This was using stock condensers. If you use modern condensers and way better fans, you should be able to get the AC really cold.

[914sgofast2]

In order to improve the airflow into the frunk mounted AC condenser, has anyone tried creating an air inlet by opening up the holes behind the front bumper that have the biground rubber plugs, like guys who run 914-6 engines do when building a front mounted oil cooler and ducting into the frunk floor?

[mepstein]

In order to improve the airflow into the frunk mounted AC condenser, has anyone tried creating an air inlet by opening up the holes behind the front bumper that have the biground rubber plugs, like guys who run 914-6 engines do when building a front mounted oil cooler and ducting into the frunk floor?

GT opening for a condenser instead of oil cooler or radiator (Suby/v8 cars). Sounds like the way to go if you are serious about a/c. It’s the optimal location for airflow.

[friethmiller]

@914sgofast2 - yes, Rick and I discussed this. Was thinking about a large, screened inlet below the front license plate [in the front valance] feeding through these round inlets with tubing into a redesigned condenser box. I know Rick recommended flipping the condenser + fan around to have it pull air through condenser (so fan not in the way of the incoming air). I'll take a look at it and see if this is doable option, thanks!

@ClayPerrine - nice! I thought of the possibilities of adding a 2nd condenser but wasn't thinking of the engine lid. (IMG:style_emoticons/default/idea.gif) This would require additional plumbing, obviously.

@mepstein - this is similar to cutting the valance, IMO. I'll have a look at some of the boxes that PMB has produced. So, on a /6 is the metal cut behind the bumper to provide the necessary air?

[mepstein]

@914sgofast2 - yes, Rick and I discussed this. Was thinking about a large, screened inlet below the front license plate [in the front valance] feeding through these round inlets with tubing into a redesigned condenser box. I know Rick recommended flipping the condenser + fan around to have it pull air through condenser (so fan not in the way of the incoming air). I'll take a look at it and see if this is doable option, thanks!

@ClayPerrine - nice! I thought of the possibilities of adding a 2nd condenser but wasn't thinking of the engine lid. (IMG:style_emoticons/default/idea.gif) This would require additional plumbing, obviously.

@mepstein - this is similar to cutting the valance, IMO. I'll have a look at some of the boxes that PMB has produced. So, on a /6 is the metal cut behind the bumper to provide the necessary air?

Doesn’t have to be. Cut some of the valance for air flow. Take out the rubber plugs. Remove the two plugs in the back of the trunk where the spare tire sits. They are just held in with seam sealer.
It’s how I did the oil cooler on my six. Some small holes to route the lines but certainly not “cutting up the car” like some people worry.

[Jeff_72]

I saw you!!. I was driving down 281 to Temple (from Granbury) and my wife spotted you driving the opposite way. Looks like there is a fairly large 914 community in the area.
(IMG:style_emoticons/default/aktion035.gif)

Well, last Friday, I set out from Austin, TX driving 160 miles north - heading to Granbury, TX to meet Rick ( @technicalninja ) in person and let him have a look at my 914's A/C system. Rick owns Granbury Auto A/C and had kindly offered to help me out and teach me how to check/service my A/C system. With my A/C blowing warm air, I figured I'd better get up there before things started getting hot here in May. I must mention that the trip up US281 was really nice and would recommend it anytime and in any direction. As soon as I arrived in Granbury, Rick and his wife welcomed me into their shop and immediately went to work diagnosing my A/C. After fixing a few wiring snafus caused by yours truly (IMG:style_emoticons/default/rolleyes.gif), Rick quickly found the leak, cleared and recharged my system, and then showed me how to check the numbers to see how my system was performing. It was interesting to see how poorly my A/C condenser and fan setup performed at idle and how things improved once I was able to move the car at speed. Rick and I discussed a few options for fixing the design of my A/C and I'm sure we has thinking about his current 914 project and how he could improve things on his car. I'm posting this here just as a prelude to some changes I have planned to my condenser/fan setup and a big "THANK YOU" to Rick and his entire family for being so kind and friendly to this complete stranger. Oh, and check out Granbury Auto AC if you need an expert who really knows what he's doing. Bravo! (IMG:style_emoticons/default/first.gif)

[technicalninja]

Probably going to try modified valance/LE air dam (I have a repop I bought from 914sixer).

Initially going to try just the holes for entrance...
I can usually "see" stuff and my eyes say "not enough" right now.
Testing before cutting is the ONLY way I do major mods.

Both my car and Fred's ALREADY have the big square hole in the front floor.

I'd like to come up with a fairly simple "modern shit" retro-fit for dealer installed air.

Mine ABSOLUTELY will have the upper surface of the box be easily removable and repairs to this will be designed to happen in the trunk. Fred's unit is especially egregious in this department.

I want to try and keep the condensers out of the engine compartment if possible but condensers in series is never a bad idea. I'm planning 2 skinny ones stacked in the front anyways.
With the "normal" condenser box in front you really have no extra room around it anyways and mine might end up looking like a second floor in the frunk.
I'm planning on placing the very largest cores I can shoe horn in.

The fan/s need to be serious as well. Fred's fan has the skinniest 16 gauge wire I've seen. Mines gonna be BIGGER, much bigger.
I'll have dedicated hi amperage bus bar for both positive and negative legs...


@clayperrine I believe I've found a v belt small Sanden that will work in reverse direction and actually mount to the original York mounting plate.
This will require welding brackets to the mount so not completely "Plug and Play".
When I find the numbers again, I'll PM you with what i have found.
It looks like the baby Sanden WILL clear the car's sheet metal. It will still require the engine tins be modified...
Hose exits are in the right place. Should have 60+ percent less rotational torque than the York and have significantly less NVH.

I'd prefer PWM computer controlled variable output compressor with serpentine drive but finding a usable "normal" replacement for the York is probably more helpful for the 914 community overall.

"Drop in" can add value...

This is the start of my busy season!
Last year I went 7 days a week 12+ hour days with father's day and July 4th off...
I'm already scheduling 3 days out and it hasn't HIT yet!
First 100 degree day and I'm going to be SNOWED IN!

One final point...
Because the car is legal for it after kicking the R134 issue I will end up back dating my car (at least) to R12. It's lower pressure curves and the size of the molecule might significantly extend the systems service life to the point of "never again" for AC repairs...

[friethmiller]

Looking to design a better scoop for my condenser. Here's some rough design work I did last night. Decided to create a cardboard mock-up to find any issues. Certainly found a few. I think the scoop is too big. I want to keep the drop-down height to about 2 1/4". This is pushing 2 3/4". The cardboard is thicker than the metal I will be using but I also attached the sides 'inside' the top and bottom pieces, which increased the overall height. Will be making modifications. This is a work in progress. Thoughts?

[friethmiller]

Ok, I got a chance to disassemble the condenser unit and potentially make some of the changes that @technicalninja recommend to hopefully increase air flow/make my a/c work like it should. A few things I noticed:

1) There has got to be a better way to bolt the condenser and fan to the bottom plate without having to sandwich it all together with the black box - all at the same time. I will design something for this.
2) The area for the intake air could be increased! I will cut the front back about an inch or so to allow for about 40% more air. This will require modifying the front of the box just a bit (see pics for marks on the trunk). This should help the problem for sure. I will also add my new intake scoop!
3) The fan kind of sucks! It's a 12"x12". I'm sure I could up the CFM with a better fan like a 12" perma-cool 2300 cfm. Suggestions?
4) The condenser isn't much better - it's a 12"x14" generic parallel flow unit. I'm sure Rick will be all over of this. Question: if I upgrade this item now, how will I be able to capture the refrigerant before swapping it out?
5). The condenser had a leak at one of the connections to the condenser and it has eaten the paint on the bottom plate. I have stopped the leak, thankfully - verified with my new leak detector. I will clean, sand, and repaint.

Here's some pics:

[technicalninja]

I like the shit out of "super cool" condensers from these folks.

https://www.oldairproducts.com/products?keyword=condenser

They make them here in N Texas.

I put a big one in a 50' Dutch Star motorhome.

Replaced a HUGE tube and fin with a relatively tiny supercool. The original manufacture went bankrupt, and the OE stuff was NLA.

Kicked ass and was far superior to the original.

Original owners ALWAYS had to run the roof air during summer travel.

After the rebuild they NEVER had to run the roof moving.

I'd sandwich two of the biggest I could shoehorn into the frunk.

Probably 16/18 or 18/17...

As for fans yours SUCKS!

blades are shaped for a puller and they just reversed polarity. Stupid!

You will need the largest PUSHER available. I'm usually hunting Spal shit or a specific OE set up.

I worry about the fan...

Most are designed for vertical installation and the thrust surfaces/bearings may not be up to the task of a horizontal installation.
Might not be an issue but worth keeping the back of your mind.

Make SURE whatever you buy is a designated pusher. Pretty much all of the motors can run backwards but unless it has perfectly flat blades (which SUCK!) the blades will definitely have an intended direction and the "cupping" will be shaped accordingly.

My source for hoses and connections:

https://coldhose.com/?utm_source=google&...ASAAEgJNP_D_BwE

I prefer steel reduced barrier stuff. Both the hoses and the crimp connectors have to show reduced barrier. DO NOT reuse old hose if possible.

A "rule of thumb" for entrances and exits is 33% of the core's face...
This is with proper ducting.
The exit is fine.
The entrance sucks big donkey dicks...

Your upside-down periscope may help but I am planning on a front entrance for my system.

Hope this helps.

I have a nice hydraulic crimper that makes short work of the hoses...

[technicalninja]

Mounting condenser notes:

The SuperCool condenser I stuck in the MH came with what looked like cheesy mounts.

These were thin straps of SS that wern't very strong.

Bend them into Z shapes and mount the condenser with 4 Z bends.

This allows for what I call a "floating" mount.

The condenser will vary nearly 400 degrees over its life.

You rigid mount anything aluminum which goes through 400-degree changes, and you WILL break it somewhere down the road.

The SuperCool condenser has flanges with a bunch of holes down the sides.

The straps and the holes make it easier to install...

The proper stack is discharge hose to lower condenser with a bridge from the output of the first condenser into the input of the second then output of second to receiver drier.

Condensers are normally discharge to top with liquid line coming from bottom.
You reverse these two and your system will die rapidly.

The oil NEEDS to come out the bottom!
It will get trapped in the condenser otherwise.

The reason I'm including this is the way I have designed is the exact opposite with the liquid line coming from the "top" of the stack instead of the bottom.

Both of these cores are horizontal, and the oil flow is probably not an issue but once again, something to think about.

I'd over oil a bit and watch how the sight glass looked.
If it's bright green I'm happy.
If it looks like water running in the drier, I'd redesign...
Clear means no oil, green means oil.

[friethmiller]

@technicalninja - yes! Thank you. First off, I was able to buy a leak detector and get a wrench on either side of that front inlet and tighten it down [wasn't exactly that tight before]. Leak detector no longer detects anything [at the highest sensitivity]. I'm going to be doing a lot changes based on your suggestions. I'm looking at flipping things around and having a better quality fan pull instead of push. I'm going to stay with this condenser for now but will be reworking things so I can more easily change it out, if I need to. I'm also looking at another air intake up front, like you mentioned, but haven't got that far on the design side yet. Working on this while also rebuilding the LE has got me super busy. This should take me a few weekends (IMG:style_emoticons/default/biggrin.gif)