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Old 05-04-2003, 08:34 AM
73MB280SEL 73MB280SEL is offline
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Join Date: Nov 2000
Location: Mustang, OK
Posts: 509

I'm certainly not an automotive A/C expert, but I drive alot of older cars, so I've done some research.

The ONLY legal substitutes for R-12 (or any ozone depleting refrigerant) are strictly limited to those listed on the EPA SNAP website:


Use other substitute refrigerants at your own risk. Once a system is converted to R134, or was originally an R134 system, it is a "grey area" as to what you can and can't use as a refrigerant. The EPA is charged only with regulating ozone depleting refrigerants.

Duracool is a hydrocarbon (flammable). I personally have no problems with this, but flammable refrigerants in any mobile form are strictly illegal in a multitude of states (including Oklahoma). Heck, we have cockfighting, but not flammable refrigerants.

To use Duracool, you MUST perform a PERMENANT conversion to an acceptable SNAP alternative first and then convert to Duracool. This means brazing in the correct fittings, charging the system, changing out the drier, etc. To then convert to Duracool would make the whole procedure $$$. If you convert directly to Duracool, your A/C guy can do jail time.

Another thing I noticed in the research I did is that both Duracool and R134 seem to have a critical temperature at 150 deg F. See the chart below:

pressure temp chart

Below a condenser temp of 80 deg F, Duracool has a lower vapor pressure than R12, which is good. Above that, however, Duracool is HARDER to liquify than R-12, but easier than R-134. Above 150 deg F, you CANNOT liquify Duracool or so it would seem. I'm sure that this is an oversimplification of Duracool's refrigeration properties, but on a hot day the evap could be running pretty hot.

Like I said, I'm no refrigeration specialist...

What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.
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