Keith,

Thanks, That clears the air a lot.

Regards,

John Rodgers
88 GL Driver

Keith Hughes wrote:
>> ------------------------------
>>
>> Date:    Thu, 7 Sep 2006 16:14:15 -0500
>> From:    John Rodgers <inua@CHARTER.NET>
>> Subject: Re: a/c - Sorry
>>
>> In reading the rules, here is my understanding of this AC thing.
>>
>> You can ONLY convert to 134a directly from R12. You cannot convert
>> DIRECTLY to anything else. To convert to 134a requires certain steps for
>> safety and the simple mechanics of the process. But VERY importantly,
>> the inlet and outlet filler valves have to be changed from R12 type to
>> 134a type, and a tag has to be put on the system in a visible place
>> saying it has been converted and has 134a in the system.
>>
>> The rules don't say that you can't convert to another refrigerant at
>> this point. They don't exactly say you can, but they don't say you can't
>> either. But they do say that IF you convert to one of the approved
>> alternate refrigerants like Freeze 12, you must follow procedures
>> prescribed and also change one valve - I think it is the fill valve
>> connection - back to that of R12.
>>
> Mostly correct.  You have to change the service connections to Freeze-12
> fittings.  Each refrigerant has to have its own fittings, and the
> vehicle has to be labeled as to which refrigerant is installed.  Also,
> if the receiver/drier is fitted with a high pressure relief plug (very
> likely), then the system has to be fitted with a high refrigerant
> pressure compressor cutout switch (the vanagon high refrigerant pressure
> switch - at least 1986-88 - turns on the high speed radiator fan, and
> the radiator high temp switch cuts off the compressor, which doesn't
> legally qualify).
>
> There are a number of downsides to Freeze-12:
>
> * It is a blend of R142a and 134a, and therefore may leak out/diffuse at
> different rates, so 'topping off' may change the mixture (and cooling
> efficiency)  over time.
> * Freeze 12 is not very good at carrying mineral oil, and the system
> really should be flushed, the receiver/drier replaced, and the system
> filled with PAG/POE oil before charging.
> * Freeze 12 has to be recovered with dedicated equipment, so you should
> make sure there are a sufficient number of shops in your area that have
> recovery equipment, or you'll be hosed when you need some repair.
> Freeze 12 *must* be removed prior to mechanical servicing, so you have
> to have someone equipped for Freeze 12.  Depending on where you are,
> might be a problem or might not.
>
> That said, Freeze 12, when properly retrofitted, works very well, and
> much better than R-134a.  And like with R-12, you have to have an EPA
> 608/609 license to buy it.  You can get certified on line through MACS,
> at http://www.macsw.org/certification.php.
>
> Keith Hughes
> '86 Westy Tiico
>
>