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Discussion Starter #1
In the efforts to improve the Elise/Exige's A/C cooling capability, has anyone tried Duracool as a replacement for the stock r134a refrigerant?

Duracool®.com 2004 - Duracool® is The Recognized Leader In Hydrocarbon Refrigerant Technology

Supposedly, it's slightly more efficient than r12... which makes it much more efficient than r134a.

Would this even work considering some people have problems with the system icing up as it is stock? Or would the increased cooling efficiency compound the icing problems?
 

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Legal Status of HC-12a ®, DURACOOL 12a ®, and OZ-12 ® | Alternatives / SNAP | US EPA

Not answering your question...:)...but...

If you go into a shop to have your A/C charged, they won't touch it unless you have straight 134a in your system, other refrigerants screw up their equipment by mixing non-approved derivatives of 134a.

I just did one of our cars with 134a (new compressor, accumulator, orifice tube, lines, etc.) and the secret is pulling a good vacuum. You should have a good manifold set to read the gauges. I have a special vac pump that will pull 20 microns...that takes care of the main problem (moisture in the system). The air is frigid after the install. Not many shops (I wonder if the manufactures do) will pull that much vacuum when working on air systems and as a result, their work is not always optimal. Some shops may have equipment to pull 15 microns, but rarely waste the time to even pull 75 or 200 from what I've come across. That's why I do my own. HTH
 

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Discussion Starter #4
Thanks for the info... If I interpret the politics correctly:

It all comes down to what type of HC-12a you've got. Two versions exist (or existed.) One was submitted to SNAP and the DOT for testing pre-1998 and was deemed illegal for DOT use.

In 1998 the formulation was changed, but was not resubmitted for testing to SNAP (EPA). It seems to have passed the DOT regs for shipment. But since it never went through SNAP, it can't be MARKETED as a substitute for ozone-depleting refrigerants (like the old R12.)

Technically, it *can* be used to replace non-ozone-depleting refrigerants such as R134a. But, at that point the states come in which potentially makes its use, because it's flammable, illegal... but only in some places:

Arkansas, Arizona, Connecticut, Florida, Idaho, Iowa, Indiana, Kansas, Louisiana, Maryland, Nebraska, North Dakota, Oklahoma, Texas, Utah, Virginia, Washington, Wisconsin, and the District of Columbia.

Ironic since, R134a is flammable (but only under pressure.)

So, am I going too far in assessing that aside from use in those above mentioned states... the use of Duracool (provided it's not the old HC-12a blend known as Hydrocarbon Blend B) is legal in some states?

Regardless... would it even make a difference in our cars?
 

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i've commented before, my a/c and heater were quite marginal when i got the car.
i found that there was considerable airflow even when the outside air was off.
i taped the intakes behind the front grille and the HVAC works much better.
the heater heats and the a/c cools.
i have to remember to hit the recirc switch when i use the heater or a/c .
not perfect but noticeably better.
sam
 

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Some owners seem to have acceptable A/C. others don't. I have to wonder as Ol' Racer said, if Lotus did the charging properly.

I'm replacing everything on an R12 system and have been learning a lot. I've studied the vacuum pumps and other things necessary. I bought a nice US made 2 stage 15 micron pump and some decent gauges. After buying a new Delphi compressor, I found that it will void the warranty if substitutes such as Freeze 12 is used. I assume Lotus will not warranty their parts if anything but 134a is used. I considered using a 134a substitute in the lotus myself. Just be aware of the warranty situation.

I also feel that you would do well to evacuate the system, pull a high vacuum, leave it under vacuum for hours (let the vacuum do its job), then recharge with the proper amount of 134a (and some UV dye). Then hook up some high/low pressure gauges and see what you get.

I have a gut feeling the design of the system is not the best. Even Lotus says so in effect. It could be the orifice system isn't sized properly, compressor not adequate for pressure at given flow or something else. Gauges and an infrared temp gun or thermocouples could determine this. Anyway, I'd evacuate, get all moisture out, recharge and see if it doesn't improve.

By the way, the later cars have the sensor in the evaporator placed in the new location. No evaporator freezing in Phoenix, but not much cooling either.
 

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Many people swear by Tonywa28's heater bypass mod.

I did it 10 days ago and the difference is notable, if not extreme.

Also, make sure that the coolant system doesn't have air bubbles in it. The cab is surrounded by hot water (in the sills) and every degree counts. After I bled the system, I consistently have engine temps 10 degrees less. It makes a big difference in these tiny cars.
 

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Overlander23, there is no technicality involved except in the minds of those who benefit from the sale of that HC product. More like self interest than "politics". The EPA considers those products to create a very real risk to occupants of vehicles. There are some EPA approved refrigerants other than R12 and R134A, but those are listed on the EPA website and do not include HC refrigerants. Read what Ol'Racer says above. I would add that no car manufacturers and no ac parts manufacturers will warranty their products if they have been used with anything other than R134A or R12. In addition, anyone using unapproved refrigerants for a consideration (payment) are in violation. That would not include you if you do it for yourself.
 

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I found after 3 years that my A/C was blowing outside temps no matter what. I was worried that I had a leak but the only way to tell was to recharge and see if it held. I bought a simple recharge kit with gauge and set to the process. I found the trick that should help:

  1. Take off the right rear tire and fender well liner. If you are really tall you might be able to do it without this step but being my size, it was a necessity.
  2. Lead the hose thru the right side vents to the engine compartment.
  3. Reach thru the fender well to attach the hose.
  4. Now the recharge can and gauge are on the outside and easy to manipulate.
 

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  1. Take off the right rear tire and fender well liner. If you are really tall you might be able to do it without this step but being my size, it was a necessity.
  2. Lead the hose thru the right side vents to the engine compartment.
  3. Reach thru the fender well to attach the hose.
  4. Now the recharge can and gauge are on the outside and easy to manipulate.
This will come in handy when I am ready to start huffing freon (again).
 

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The system has a number of design flaws;
1) Evaporator coil too small
2) Output ducting too small
3) Input ductingi too small
4) Thermostat does not react quickly enough to shut off compressor and stop the evaporator coil from freezing.
I made some modifications to my car that has the A/C working adequately.
 

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A great trick for removing moisture from an A/C system that has been open for repairs is to use nitrogen.

Once the system is closed, pump it up to 250-300 psi with nitrogen. this allows you to check for leaks without wasting refrigerant or having to recover or dump the refrigerant if there are leaks.

If the system does not loose pressure after 12- 24 hours, your are good to go.

Compressed nitrogen is anhydrous (has no moisture in it) so it acts like a sponge for any moisture in the system.

Dump the nitrogen into the atmosphere and, if you really want to be extra moisture free, pressurize and dump the nitrogen one more time.

Now, hook up any decent vacuum pump and suck out the remaining nitrogen.

Fill the system with refrigerant and you will now have a moisture free system that will work at maximum efficiency

Don't forget to replace the dryer on any AC system that has been opened.

Nitrogen is available at welding gas suppliers.
 

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Just a word of caution when using r134a or r12 alternatives. Your compressor warranty is automatically voided. This is with any company that produces new or reman compressors. Also, failure to replace the filter/dryer, orifice tube, and accumulator plus flushing the system (PROPERLY) will result in a voided warranty. In some cases (a few Ford applications) the condenser must also be replaced.
 

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Viper, as a fellow Floridian what specific mods did you make to your car to make the A/C work better? Which ones were the most effective?
 

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I realized that I could not improve, or actually make the A/C system work better (except for one item), so I took a different tact.
I decided to reduce the cabin heat that the system had to overcome, and this was two fold.
1) Reduce the solar heat through the glass.
2) Insulate the side sills where the hot coolant, heater and oil lines run.
The one actual impovement to the system was intended to stop the evaporator coil freezing by installing an improved thermostat.
The end result is that my car is far more comfortable to drive in the summer.
Michael
Viper, as a fellow Floridian what specific mods did you make to your car to make the A/C work better? Which ones were the most effective?
 

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Discussion Starter #16
I haven't had my sills open yet... But speaking of #2, did you merely insulate the side walls of the chassis? Or did you wrap the water/oil lines? Are they accessible for something like a foam wrap?


I realized that I could not improve, or actually make the A/C system work better (except for one item), so I took a different tact.
I decided to reduce the cabin heat that the system had to overcome, and this was two fold.
1) Reduce the solar heat through the glass.
2) Insulate the side sills where the hot coolant, heater and oil lines run.
The one actual impovement to the system was intended to stop the evaporator coil freezing by installing an improved thermostat.
The end result is that my car is far more comfortable to drive in the summer.
Michael
 

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I insulated the side sills and front firewalls on the inside of the cockpit, it reduced surface temperature by 20' .

I haven't had my sills open yet... But speaking of #2, did you merely insulate the side walls of the chassis? Or did you wrap the water/oil lines? Are they accessible for something like a foam wrap?
 

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I also feel that you would do well to evacuate the system, pull a high vacuum, leave it under vacuum for hours (let the vacuum do its job), then recharge with the proper amount of 134a (and some UV dye). Then hook up some high/low pressure gauges and see what you get. .
An hour will be sufficient, then charge it to Zero pressure, pull another 15 minute vacuum, charge to Zero again and then another 15 minute vacuum. Much better way to be assured to get the moisture out.
 

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nitrogen leak testing

The suggestion to use nitrogen for leak testing is excellent. If you have a very good electronics leak detector, the pressure from the nitrogen will amplify the traces of refrigerant and make leak detection easier. However, all that is required for this is 50 psi or more. Also, pressurizing the system above 150 psi is not a good idea in cars, as evaporators are generally designed to operate between 15 and 60 psi. They rarely exceed a static pressure of 150 psi when a system equalizes after shut down.
 

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Your right you don't have to use that much pressure. 150 psi will do.

However, If you keep it to low you can miss leaks on the high pressure side.

I learned this technique form a auto A/C guru who has done it thousands of times with no trouble.

However, proceed at you own risk and you mileage may vary. :crazyeyes

Pressurized nitrogen will always remove more moisture than vacuum alone possibly can.
 
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