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Can this work?

lotus4s on Sat September 11, 2010 1:08 PM User is offline

Year: 1995
Make: Lotus
Model: Esprit
Engine Size: 2.2l
Refrigerant Type: R134a

First, thanks to the forum for a ton of great info and help with solving previous AC issues.

I have a 1995 Lotus Esprit that was originally fitted with R134a and the cooling is/was notoriously poor even from new. I would like to retrofit the system to R12 as used in the 1994 models which cools wonderfully.

The current system uses two PF condensors linked together in parallel (corrected, thanks) with a total dimension of 36" x 9.75". The largest single condensor that I can get through ACKITS that will fit is 27" x 10.5" and I've been told this should work fine.

Can I get greater efficiency using the newer PF 27x10.5 with R-12 than using the linked two smaller units? My logic says the linked system must be losing efficiency but my logic has been wrong before. ;-)

FWIW, the inlet opening in the front of the car measures approximately 27" wide x 8" high and the condensor unit is sandwiched between a charge cooler condensor and the radiator.

Compressor is a Sanden 508 using a TXV system.

Thanks for any advice.

Jim







Edited: Sat September 11, 2010 at 6:52 PM by lotus4s

htguru on Sat September 11, 2010 2:38 PM User is offlineView users profile

correctly if im wrong but aren't those hooked up in parallel? so wouldn't the refrigerant flow take the path of least resistance and make the one closer to the connections work harder then the other. it seems to me they should be run in series for maximum heat transfer.

Edited: Sat September 11, 2010 at 2:42 PM by htguru

lotus4s on Sat September 11, 2010 6:53 PM User is offline

By golly I think you're right, thanks for the correction.

So what's the consensus, will a single smaller unit with R-12 work better than the current unit with R134a?

lotus4s on Mon September 13, 2010 10:21 AM User is offline

Come on guys, help me out here. Any suggestions on how to improve this system with new readily available parts?

The cost to replace the leaking oem condensers is astronomical and I really don't want to spend the money on something that only works marginally in the first place.

Any help is sincerely appreciated.

Jim

TRB on Mon September 13, 2010 10:46 AM User is offlineView users profile

It's all about the space available. If you can get a couple MPPV condensers in the area available you could improve pressures. I also think plumbing should be in a series.

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bohica2xo on Mon September 13, 2010 11:28 AM User is offline

It has been a while since I looked at a Lotus, and I never had to work on the Esprit. That car should have a Sanden SD7H15 compressor. If someone fitted the smaller 508, performance will suffer.

You have about 300 square inches of condensor. That should get the job done,if it has airflow. Lotus spent a little too much time excluding airflow from the inside of the body - great for racing, but a problem here in the desert traffic. You don't see a lot of Lotus cars here.

Your condensor appears to have some clogged fins. What does the fan system look like on this vehicle? Is there room to put 4 fans on the face of that condensor?

Converting to R12 can lower the head pressure, but for better cooling you need condensor airflow. The system is a heat pump, and it needs to get rid of that heat.

Post some pics of the condensor / radiator area & airpath.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

lotus4s on Mon September 13, 2010 12:49 PM User is offline

B,

You are correct, the compressor is SD7H15.

Here are the pics. The chargecooler condenser, ac con and rad are sandwiched and angled back as shown in the pics. The rad core is approx 34" x 12" but the intake opening on the front of the car is 27" x 6". There are three 11" puller fans behind and the whole assembly is mounted under the car and sealed when installed.









bohica2xo on Mon September 13, 2010 1:45 PM User is offline

Well there is the answer to why a car that size got a 315 square inch condensor. The charge air cooler.

There are a few things you can consider:

Improving airflow through the existing package, and making sure the air can't bypass the condensor core in the stack.

Locating a third, small condensor in the ambient airstream (rather than the preheated air from the charge cooler) to provide some sub cooling.

I know there is not much unused space in that vehicle. A small condensor Like THIS might be placed in front of the heat exchanger stack, or even in the air inlet.

Those fans were typical 20 years ago, but things have improved some since. Perhaps a couple of small fans will fit in front of that package with the small condensor? You may also consider replacing the 3 fans with 4 new units.

Occasionally I wish I had my Europa back. At least it had plenty of room for heat exchangers...

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ice-n-tropics on Mon September 13, 2010 5:12 PM User is offline

A few observations:
1) Condensers
A) The 2 condensers have road crud only on their lower front surfaces. Maybe this is due to oily condenser leaks or maybe this indicates the possibility of some non pre filtered, non preheated ambient air flows across the bottom of the 2 parallel plumbed condensers.
If cooler air reaches the lower portion of the condensers, sub cooling of the liquid refrigerant may be occurring OK.
B) The OEM PF condensers appear to have too many parallel circuits causing low refrigerant velocity. We learned with the multi pass parallel flow condensers that heat X is optimized with designs that keep the refrigerant moving at higher velocity for greater turbulation and primary heat X surface heat exchange. Therefore, the AMA 10.5 X 27 " sounds like a possibility, but, should be centered in the vehicle 27" front panel opening (if it is in front of the fans).
C) First prize is to also have an additional condenser before the air cooler.
2) Fans
The 3 fan plenum assembly has:
A) A fan opening lip molded on the plastic opening aft of the orange blades.
This reduces the air flow, therefore the lip could be cut off.
B) The orange blades are forward of the opening.
Ideally, the fan blades would be moved rearward so that 25% to 33% of the rear of the fan blade protrudes behind the large plenum opening. The more space between the front lip of the fan blade and the radiator, the better the air is distributed evenly across the heat exchangers.
C) There are two (or more) 2 to 3 " unrestricted round hole openings in the plastic plenum which allow air recirculation.
These could be sealed. Maybe, at one time they may have had flapper valves covering the openings which opened at higher ram air due to higher road speeds.
3) Compressor
Too much compressor lube reduces condenser and evaporator heat exchange. Be sure that the factory recommended oil charge is followed when you reassemble.
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

Edited: Mon September 13, 2010 at 5:14 PM by ice-n-tropics

lotus4s on Mon September 13, 2010 9:37 PM User is offline

Gentlemen,

Thank you very much for the info and taking the time to reply.

There is no room to add a condenser or fan in front.

There is the possiblilty of making a custom shroud with 3 newer fans. Any suggestions on the fans, is Spal the way to go?

I would very much like to replace the existing condenser setup as it is 15 years old and the replacements from Lotus are $1200. I bought this car with the air not working and since I'm rebuilding most everything else on the car I wanted new parts and hopefully a system that would be as good if not better than the oem setup.

I'm leaning towards trying the 27x10.5 unit with new fans/shroud unless you guys think that would be a mistake...





bohica2xo on Tue September 14, 2010 1:18 PM User is offline

I agree with Tex, I never had success with parallel condensors - of any type.

Besides trying to make a car slippery, Lotus seemed to like the idea of picking up parts from other models. That may have been the reason for the parallel plumbing - two off the shelf condensors rather than a custom unit for that space. Probably from something even more obscure that the Esprit here in the US...

In terms of absolute core area, it should be close. The single circuit advantage should help too. Going back to R12 with the higher condensor airside temps from the charge cooler may help some as well.

The fans.
Tex covered the tip spill issues, and the vent holes. The fans themselves are not that great either. If you have the capacity to make a new shroud, you could become king of the Esprit world. I would lay up a new shroud with 4 fans if it will fit, or 3 if there is just no way around it.

Spal is a name. The aftermarket electric fan manufacturers all play games with ratings. The best indicator of fan power is the power it uses. OEM electric fan vehicles have 60a fuses, and 8ga wires in some cases. We got pretty deep into the fan set from the Ford Freestyle recently here - there is a thread on it. You may be able to use an OEM fan assembly as a starting point. Look at things like that Freestyle, the '05 to '07 GM line of things like the Saturn Vue, the Malibu, etc. The '09 Traverse has a loud set of fans, I walked past one yesterday. Look carefully at what the OEM's are doing to solve this.

The reason I recommend 4 aftermarket fans is space & relative power. If you can get 4, 9" fans in there, I would. 4 10"s would be even better. The site sponsor offers a good line of electric fans, from 9 inches up.

One last note. The pic of the assembly on the bench appears to have a fat piece of foam rubber for a top cover / seal. If that is pushed down onto the stack, it will block the top 2 inches of the radiator & condensor airflow. You might consider fabricating a top cover that seals to all of the heat exchangers independently.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

lotus4s on Tue September 14, 2010 9:06 PM User is offline

Thank you all for the info and direction. I guess now I have my homework assignment to fabricate the new shroud/fan setup.

My thoughts are to do it in aluminum and try for the 4 fans if possible. Should the shroud be completely closed except for the fan holes?

lotus4s on Tue March 22, 2011 11:28 PM User is offline

Just wanted to post an update and to sincerely thank the forum and all of you who offered advice on my project. I decided to stay with R134a at this time
to have a fair comparison to the OEM setup.

Here's the new condenser setup.




And the fiberglass fan shroud that I fabricated.




The completed assembly.




We've recently had temps in the high 80's here which has given me an opportunity to test the system and so far I could not be more please with the performance. It is better than when
the car was new with vent temps in the 38-40 degree range.

Thanks again to AMA and the forum for the quality parts and priceless info.

Jim

Edited: Tue March 22, 2011 at 11:33 PM by lotus4s

bohica2xo on Wed March 23, 2011 3:15 PM User is offline

Nice job!

Hope you kept the buck for that part, there are other Lotus owners out there sweating...

If you are getting improved cooling, you are also getting more airflow over the charge air cooler - a win on both ends.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ice-n-tropics on Wed March 23, 2011 9:03 PM User is offline

Thank's for the update with pictures.
Looks like good engineering to improve the refrigerant velocity management.
Would have been interesting to compare the charge air cooler (CAC) performance.
Improved cooling in the charge air cooler due to increased air flow also extends turbo equipped engine life.
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

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