[DeTomaso] R 12 conversions

David Gardner close_enough at losalamos.com
Wed Sep 1 22:25:01 EDT 2010


I'm not certain this question was answered in sufficient technical  
detail, so I have asked a hobbyist friend specializing in air  
conditioning to post on the thread.  His name is Jim Sims.

We build our own systems, rather than having shops do it, and have the  
swaging tools to make lines, a vacuum pump, an ultrasonic leak  
detector, valve assemblies, etc.  We also install an additional  
counterflow heat exchanger to harvest some of the cooling power  
remaining the in the gas exiting the evaporator, and have moved to  
fabricating our own aluminum lines. The best we have achieved is 38 F  
exiting the vent on a '72 911.  We installed a new system on my  
Pantera, but have not yet charged it.  Below is his first response,  
but I asked that he post.

"what do I suggest I do?  Compose and submit my suggestions based on  
our limited experience?  We have never charged and run your system.   
If his system is tight (passes a pressure/vacuum pump down test after  
having any residual R-12 removed and recycled) he can indeed do a  
basic conversion:

Pull the condenser and flush.  Remove the expansion valve from the  
evaporator, flush evaporator, install a bit of R-134a compatible  
refrigerant oil and reinstall expansion valve but I would just install  
a new valve given how inexpensive they are, provided one doesn't get  
them from a Pantera parts source.  Pull the compressor and fill with  
R-134a compatible refrigerant oil.  Drain/blow out the existing hoses  
of R-12 mineral refrigerant oil but do not flush (R-12 mineral oil  
will stay in place and reduce the permeability of the hose to R-134a).  
Replace the R/D and install a bit of the new oil in it.  Pump down (~3  
hours) and recharge."

Cheers,
David





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