Re: R-12 A/C '93 Dakota question

From: Richard Brown (Richard.Brown@MCI.Com)
Date: Thu Jul 17 1997 - 12:41:45 EDT


Note: This was lifted from a previous message I received from Daniel
Stern, so don't respond to ME if you have any questions. I'm no A/C
expert... ;-)
==========================================================================

Basically, DO NOT(!) convert your R12 car to R134a or any of the
R134a-based refrigerants (FRIGC comes to mind). They are far less
efficient than R12 and R406A, GHG-X4, etc. Also, they are HIGHLY

incompatible with R12-type oil. THey operate at radically different
pressures, so calibration of R12 expansion valves won't be optimal. Also,
since 134a is so inefficient, one must use larger compressors, condensors,
and evaporators to get the same level of cooling as from an R12 system.

This is difficult and expensive to do on an existing system, so you get
much less cooling with 134a. To convert to 134a PROPERLY so as not to
shell any of the components, you're going to need:

- Barrier-style hoses (The R12 hoses are
  permeable to the smaller R134a molecules)

- All new seals and O-rings (ditto above)

- A rebuild or thorough flush of your compressor.
  Which one you will need depends on the design of the
  compressor. Early CHrysler compressors, for instance,
  use an oil sump and pump which cannot be "flushed" of
  oil like non-sump type designs, and because 134a is so
  violently incompatible with 12-type oil, you have to get
  ALL of the old oil out.)

- New receiver-dryer with XH7 or XH9 desiccant

- And you should really purchase a parallel-flow condenser
  to try and make the system work at least marginally, if
  not optimally well.

Now let's compare that to using R406a or GHG-X4:

- They are MORE efficient than 12, yet it operates at
  similar pressures, so the expansion valve calibration
  will remain optimal and your existing condenser and
  evaporator will function MORE than adequately.

- They are completely compatible with R12 type oil, so no
  system flush or expensive compressor rebuild.

- You still need barrier hoses, because R12 type hoses are
  permeable to the smaller R406a factions' molecules.

- Ditto new seals. (New hose-to-hose and component-to-component
  seals, you don't have to mess with any compressor or other
  internal seals).

The choice is crystal clear here, isn't it?

Now I have to ask YOU a question: Why are you converting to anything?
R12 is still around, you know, and anyone who tells you otherwise is
lying or ill-informed. There is plenty of it in the US. There is MORE
than plenty of it in the US.

Some garages will tell you that R134a is the only legal refrigerant.
That's wrong. (You don't have to take my word for it, either. Go to the
EPA SNAP (Significant New <refrigerant> Alternatives Plan) homepage and
see for yourself that 406a and GHG-X4 have passed all the safety tests,
are certified nonflammable/noncorrosive, etc.

Some will tell you that 134a "moves more heat" than R12.
That's also wrong. Some will tell you that no flush, rebuild, or anything
else is needed when converting to 134a, and that you can just drop 134a
into an existing system. For most systems, That's dangerously wrong.
Either use 12, or use 406a, or use GHG-X4.

Information on conversions and refrigerant alternatives can be found at
http://worldserver.com/ghg/index.html#GHG-X4

Daniel Stern "a T3 2.2, a 2.5, and 2 225s."
Licensed s.609 Automotive A/C Technician
Automotive Headlamp Specialist At Large
                                         Website Items:
http://ursula.uoregon.edu/~dastern <-----All Things Daniel and Pizza |

 



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