Suppose a crazy person was thinking of A/C in their 914. Could such a crazy person run condensors in series behind the fog light grills?

Basically, the refrigerant (R134) would come from the compressor all the way up to the right front under the headlight, go through a condensor, come out of that condensor across the front of trunk, into a second condensor under the left head light area, and then back out to a receiver/dryer and through the rest of the system.

Obviously, there are some cuts you need to make in the front area behind the fog light grills, the condensors have to be small enough to fit under the headlights when close and for good enough air flow you have to have cut holes in the front wheel well behind the condensors.

I know someone on this board mounted some oil coolers in these locations (can't find the thread).

914 A/C reference from http://www.914world.com/bbs2/index.php?sho...=192917&hl= (thanks dlee6204).

If you could make it work, put two in parallel. That way they condense at the same rate.

I was thinking I would run parallel flow condensors in series.

But how would you ever be able to put fans on them?

Why? Saving trunk space? Are you H20 or air cooled?

http://www.914world.com/bbs2/index.php?showtopic=56102

Goto page 13

You can run condensors in series. The 911s did that. Each one you add gets less effective at removing heat, since the earlier ones will have removed some heat already. But the later ones will have some effect.

Running them in parallel would seem, to me, to raise issues of flow balance that I'd really rather not think about.

--DD

I'm just exploring the idea. For my build, I'm willing to get rid of the foglights and go with a "plain" grill there. Also willing to move the horns if they are in the way. Given the space there, I could also mount them pseudo-flush with the front of the chassis in that spot.

I'll be a Type IV 2270 when I finish my rustoration.

I guess the question is "how less effective will they be in series?" Seems like if it was good enough for the 911 (and the boys in Stuttgart) then it will be good enough for me. :-)

There were differences, though. Both condensers on the 911 had fans pulling air through them (electric on the front-mounted one; the engine fan on the rear one). They were also much larger than the 914 foglight grilles. But the 911 has more interior space to cool than the 914 does.

Oh, and the 911 was not known for highly-effective air conditioning. At least, not without modifications to the system (like the Kuehl Air system I installed on my wife's car).

--DD

Griffiths.com does this for the 911. It's called Mr Ice Project or something like that. I got a quote for my 930 for over $3k.

Flow balance isn't that hard if you keep equal lengths of tubing and equal number of elbows. The tubing systems should be mirror images and meet in the middle at a T. You could fine tune from there if needed.

Wouldn't the catch be whether the condensers were exactly the same. We know the pipe and fittings will all be congruent but what are the odds all of those fintubes flow equally.
Didn't Dlee in Houston just add AC to an air cooled teener last year? Might be some good info in his thread.

The question is can you find a pair of 11x13 condensers? Or Y fittings?

Plus for the amount of work involved, mounting in the trunk floor or engine lid makes a lot of sense.

I can definitely find condensors in that size or have them made custom. I believe the opening of the fog light grill is about 8.5" by 6".

You need to figure the temperature split first as a basis for design and then the condensor size.

Then figure the size and then a location where you can get adequate heat transfer.....free flow....inductive......ect.
.

I chose to put my oil coolers in series because I figured the peace of mind that it will never become "unbalanced" outweighs the relatively small difference in cooling efficiency.

I think the concept behind the series coolers being less efficient is the following:
As hot oil enters cooler 1 the cooling efficiency is proportional to the temperature difference between the oil and the air moving through the cooler.
As the hot oil is cooled by cooler #1, it enters cooler #2 at a lower temperature than when it entered cooler #1 so the 2nd cooler is less efficient.

But to me it seems like a long skinny cooler would have the same effect. The cooling efficiency goes down as the fluid travels from one end to the other anyway.

[quote name='stugray' date='Aug 6 2015, 04:48 PM' post='2219841']
I chose to put my oil coolers in series because I figured the peace of mind that it will never become "unbalanced" outweighs the relatively small difference in cooling efficiency.

I think the concept behind the series coolers being less efficient is the following:
As hot oil enters cooler 1 the cooling efficiency is proportional to the temperature difference between the oil and the air moving through the cooler.
As the hot oil is cooled by cooler #1, it enters cooler #2 at a lower temperature than when it entered cooler #1 so the 2nd cooler is less efficient.

But to me it seems like a long skinny cooler would have the same effect. The cooling efficiency goes down as the fluid travels from one end to the other anyway.
[/quote

Stu...now I know how you got us to Pluto!

There is most probably no advantage to configure them like that. My 02.

.....I quess my statement needs context. There is probably no advantage to configure a condensing coil(s) in a series with that size as described like Stu configured his for cooling oil.

The interesting thing to me is that nobody tried getting the re-heat on the coils. At least not that I know of from the posts and threads. This would make a big difference in humid environments. I read and noticed though that the guy that eliminated the heat gain from the windows and radiant heat got the greater splits because of the heat gain.

I won't get into the thermodynamics......my wife rolls her eyes up in the back of her head when I start that.

This is the garage.

What do you mean "re-heat on the coils"?

--DD

I don't think the loss in efficiency due to the drop in the Freon temperature as it reaches the second condenser would be an issue.

Many AC condensers are a single or a pair of tubes that snake back and forth across the condenser. If you compared a large condenser like this with say 10 feet of tubing to 2 smaller ones with say 5 feet of tubing each, you will get the same type of drop in efficiency with the large one as the Freon travels thru the same length of cooling tube.

If everything else about the condensers are the same (air flow, tube construction, fins , etc...), at any point along the way in the large condenser the Freon should have lost the same amount of heat as it would at the same distance thru the 2 condensers.

Just thinking out loud ... well in my head buy typing it.

Jim

Stugray, how did the oil coolers end up working for you up front in this configuration? I think the results you saw will have a similar result for putting AC condensors in this area.

Has to do with the psych curve Dave:

https://en.wikipedia.org/wiki/Psychrometrics

It seems to me the only guys that would need AC in a teener are the ones that live in really humid environs. AC is all about "feeling cool". The air will "feel" cooler" if it is drier basically.

They almost work too good.
The first weekend out I used just the stock cooler and saw 260 once.
Hooked up the coolers and now never see above 220.

Full blown racing, and I havent been able to get my oil temp above 220 so far since I installed them.
But I havent had the balls (yet) to keep the RPMs in the 5-6k range for the entire 20 min race like some of the others.

I thought the question was whether or not the size area was sufficient to get the Freon back to a liquid.

If the question is if they can be run in a series like that then yes.

Whether it will work or not I guess is another question.

Well, yes that is the ultimate question if they are efficient enough to get the freon (well, R134 these days) back to liquid. Given Stugrays success with the oil coolers then it might be possible.

Depending on where I mount them there (flush with front of the chassis or more down inside below the headlight area) would determine if I could put a fan on them also (either push or pull fan). Of course, Stugray's cutting holes in the wheel well was the other key to getting air flow through. Stugray, did you put fans on your oil coolers up there (pushing or pulling)?

I'm digging on the input. This is certainly a thought experiment that may actually work. And if you think this is crazy, go read my thread on using the boxster blower box and control system to run this system. http://www.914world.com/bbs2/index.php?sho...=257374&hl=

I did not put fans in but there is room for a 140mm fan on each cooler.

I was reading about compressor mounting in another thread and then stumbled across electric compressors.

I believe McMark has found alternators (GM brand?) at 150 Amp(or even bigger) that mount in the type IV like original. On my rebuild, I am definitely planning to go with a larger than stcok alternator and had pretty much settled on at least this size.

So given a big enough alternator, I could mount an electric compressor up front and keep the whole system contained within the front trunk. Need to make sure I run the extra wires during the rebuild of the car, but that's easy to do when it's all apart anyway. I'll probably run a custom setup of some extra wires through the tunnel for any future modiciations anyway.

The electric compressors require quite a high amperage to run on 12 Volts, so a large alternator and some very large guage wire to the front would be required. If the compressor issue can be addressed, the entire unit could easily fit in the front trunk. Cutting into the floor of the front trunk really shouldn't be more of an issue than cutting into the engine shelf to mount an engine mounted compressor.

Yes:

http://www.jegs.com/p/JEGS-Performance-Pro...151133/10002/-1

I am pretty sure my 99 Suburban has a rear electric AC compressor, but not positive.
If so those are a dime a dozen.

Wow pricey!! http://www.jegs.com/i/JEGS-Performance-Pro...133#moreDetails

Lists Voltage range of 9-30V and 31 Amps (probably a max). Anyway 12V x 30 Amps = 360 Watts. Seems like that will not be enough compressor. Would need need to amplify the power closer to 30V.

Nissan Leaf $250ish

I don't have the formulas, but really any 12vdc motor can be attached to any common compressor. I'd go Sanden for the aftermarket support.

Hmmm that's a nice option. I'm not seeing anything on AMPS that it draws. If my math is correct, ~900Watts converts to about 1.2HP. That would mean that this unit needs 75 AMPS @ 12V to create that much HP.

I think the Sanden compressors are at 1.5HP? To get closer to 1.5HP on the electric compressor you would need 100AMPS running at 12V (1200 Watts = 1.6HP).

Doable with a 150AMP GM Alternator....

The Leaf 's electric AC compressor does NOT operate on 12 volts.
It operates as part of the Leaf's high voltage system which which the warning labels say can be as high as 500 volts but the specs on the Li-ion battery list it at 360 volts.

Jim

Everything I read on it says it is 12V. Certainly there would be some step-down from the primary battery (operating at super high voltages) to the individual components in the system. Otherwise, you would need a stereo that can take in high voltage, electric window motors that take in high voltage, windshield wipers, etc, etc....

http://fengauto.en.alibaba.com/product/600...AES28AV3AA.html

The Leaf has a complete separate 12 volt system to support the standard automotive bits and pieces such as stereos and window motors.

In the Nissan procedure to remove and reinstall the compressor there are 16 references to "High Voltage" or "High Voltage connector" including a set of images showing the High Voltage connector and how to unlock and lock it. There is also a low voltage connector on the compressor.


Here is the text of the procedure, I did not take the time to download all the iamges so the text reads a little odd where there were images but you can read the references to disconnecting and connecting the high voltage connector.

From Nissan's R&I Procedure:


2014 Nissan-Datsun Leaf ELE-Electric Engine
Vehicle » Heating and Air Conditioning » Compressor HVAC » Service and Repair » Electric Compressor » Removal And Installation

ELECTRIC COMPRESSOR

Removal and Installation

DANGER:
Since hybrid vehicles and electric vehicles contain a high voltage battery, there is the risk of electric shock, electric leakage, or similar accidents if the high voltage component and vehicle are handled incorrectly. Be sure to follow the correct work procedures when performing inspection and maintenance.

WARNING:
- Be sure to remove the service plug in order to disconnect the high voltage circuits before performing inspection or maintenance of high voltage system harnesses and parts.
- The removed service plug must always be carried in a pocket of the responsible worker or placed in the tool box during the procedure to prevent the plug from being connected by mistake.
- Be sure to wear insulating protective equipment consisting of glove, shoes, face shield and glasses before beginning work on the high voltage system.
- Never allow workers other than the responsible person to touch the vehicle containing high voltage parts. To keep others from touching the high voltage parts, these parts must be covered with an insulating sheet except when using them. Refer to "High Voltage Precautions" See: Service Precautions\High Voltage Precautions.

CAUTION:
Never bring the vehicle into the READY status with the service plug removed unless otherwise instructed in the Service Manual. A malfunction may occur if this is not observed.

REMOVAL

WARNING:
Disconnect high voltage circuit. Refer to "How to Disconnect High Voltage" See: Body and Frame\High Voltage System Disable / Enable\Service and Repair.
1.Check voltage in high voltage circuit. (Check that condenser are discharged.)
a.Lift up the vehicle, and then remove Li-ion battery under covers. Refer to "Exploded View" See: Electric Drive Systems\Battery / Power Control System\Battery\Service and Repair\Li-Ion Battery\Exploded View.
b.Disconnect high voltage connector from front side of Li-ion battery. Refer to "Removal and Installation" See: Electric Drive Systems\Battery / Power Control System\Battery\Service and Repair\Li-Ion Battery\Removal And Installation.
c.Measure voltage between high voltage harness terminals.

Standard: 5 V or less

CAUTION:
For voltage measurements, use a tester which can measure to 500 V or higher.
2.Use the refrigerant recovery equipment (for HFC134a) and recover the refrigerant. See: Refrigerant\Service and Repair\Recycle Refrigerant\With Heat Pump System, "Recycle
Refrigerant".
3.Remove radiator upper grille. Refer to "RADIATOR UPPER GRILLE : Removal and Installation" See: Body and Frame\Radiator Support\Service and Repair\Radiator Upper Grille.
4.Remove bolt (A) and disconnect low-pressure flexible hose from electric compressor.

CAUTION:
- Cover the low pressure port of the electric compressor with a cap to prevent oil from spilling.
- To prevent the inclusion of foreign matter, use a cap or vinyl tape to seal off the pipe connection port from the atmosphere.
5.Remove bolts (A) and disconnect high-pressure flexible hose from electric compressor.

CAUTION:
- Cover the high pressure port of the electric compressor with a cap to prevent oil from spilling.
- To prevent the inclusion of foreign matter, use a cap or vinyl tape to seal off the pipe connection port from the atmosphere.
6.Disconnect quick charge port connectors (1) inside motor room.

White arrow indicates : Vehicle front

- To prevent electric shock hazards, immediately wrap insulating tape around disconnected high voltage connector terminals.
7.Disconnect normal charge port connector (1) inside motor room.

White arrow indicates : Vehicle front

- To prevent electric shock hazards, immediately wrap insulating tape around disconnected high voltage connector terminals.
8.Move the water hose to a position where it will not interfere with work.
9.Remove front under cover. Refer to "FRONT UNDER COVER : Removal and Installation" See: Body and Frame\Exterior Moulding / Trim\Underbody Cover\Service and Repair\Front Under Cover.
10.Remove front wheel and tire (RH). Refer to "Removal and Installation" See: Maintenance\Wheels and Tires\Wheels\Service and Repair\Removal and Replacement\Removal and Installation.
11.Remove fender protector. Refer to "FENDER PROTECTOR : Removal and Installation" See: Body and Frame\Fender\Front Fender\Front Fender Liner\Service and Repair\Removal and Installation.
12.Remove bolt (A), and then remove compressor stay.

13.Disconnect high voltage harness connector.

- To prevent electric shock hazards, immediately wrap insulating tape around disconnected high voltage connector terminals.

- Follow the procedure below and disconnect high voltage harness connector.

14.Disconnect low voltage harness connector.

15.Remove bolts (A) from electric compressor (1).

16.Remove electric compressor (1) from the vehicle.

INSTALLATION

Note the following items, and then install in the reverse order of removal.

CAUTION:
- Be sure to reinstall high voltage harness clips in their original positions. If a clip is damaged, replace it with a new clip before installing.
- Before installing the new compressor, adjust the compressor oil level. Refer to "Lubricant Adjusting Procedure for Compressor Replacement" See: Lubricant\With Heat Pump System.
- To prevent degradation in insulation performance, use special electric compressor oil as the compressor oil.
- In order to prevent conventional PAG oil from becoming mixed in, never reuse recovered compressor oil and instead always use new oil. The use of oil including the conventional PAG oil may degrade the performance of insulation.
- To prevent performance degradation, never use a fluorescent agent in order to detect refrigerant leakage. Also be careful that a fluorescent agent never enter the oil.
- To prevent leakage of refrigerant, replace the O-ring with a new one. Apply a coat of compressor oil to the O-ring prior to installation.
- Perform a check for refrigerant leakage when charging with refrigerant. Refer to "Check Refrigerant Leakage" See: Refrigerant\Service and Repair\Check Refrigerant Leakage\With Heat Pump System.
- Set the vehicle to READY and operate the air-conditioner for at lease 1 minute with the vehicle parked to perform a break-in.
- If the compressor stay was replaced, first check that there is no dust or dirt on the surface of the compressor stay, then apply the new high voltage warning label at position (A), with the direction indicated by the arrow facing up.

White arrow indicates : Application direction of the label

- Follow the procedure below and connect the high voltage harness connector.

- After all parts are installed, be sure to check the equipotential. Refer to "Inspection" See: Inspection\With Heat Pump System.

Wow! The Nissan Leaf unit is actually a heat pump? I am really out of it when it comes to modern vehicles. I didn't realize Chevy Suburban's had electric compressors for the rear compartment. And I didn't know that there were electric compressors in the Toyota Prius and Nissan Leaf. And now a heat pump as well.

I'd like to see a 914 AC system diagramed on a psych chart. I'd also like to see how one would utilize re-heat on a 914 AC system.

I alrwady brought that up

The response was