RE: [DMCForum] Here it comes again... the R134 conversion

[Travis Goodwin <tgoodwin@xxxxxxxxxxxx>]

Excellent. This is what I needed. A good starting off point. I will report
back when I start this project.

> -----Original Message-----
> From: Dave Stragand [mailto:dave.stragand@xxxxxxxxxxxxxxx]
> Sent: Monday, March 15, 2004 2:58 PM
> To: DMCForum@xxxxxxxxxxxxxxx
> Subject: Re: [DMCForum] Here it comes again... the R134 conversion
> 
> Not hard if you follow the instructions, and use the proper tools as
> specified in the email.  I've done similar conversions on many cars
> without issues.  The best bet is just to pick up an R134a conversion kit
> at Pep Boys -- it has the hose, 2 cans of R134, and the necessary
> fittings.
>   ----- Original Message -----
>   From: Travis Goodwin
>   To: 'DMCForum@xxxxxxxxxxxxxxx'
>   Sent: Monday, March 15, 2004 1:59 PM
>   Subject: RE: [DMCForum] Here it comes again... the R134 conversion
> 
> 
>   I can do just about anything on the car but I have never touched an AC
>   system. How would you rate this conversion as far as difficulty?
> 
>   > -----Original Message-----
>   > From: Dave Stragand [mailto:dave.stragand@xxxxxxxxxxxxxxx]
>   > Sent: Monday, March 15, 2004 1:18 PM
>   > To: DMCForum@xxxxxxxxxxxxxxx
>   > Subject: Re: [DMCForum] Here it comes again... the R134 conversion
>   >
>   > >From my FAQ:
>   >
>   > This is a fairly complete checklist for the conversion based on
>   > Sanden/Sankyo's own instructions, material gathered from the web, and
> the
>   > wisdom of those DMC owners who have already completed this procedure.
>   > 1) If the R-12 vehicle air conditioning system is operational, run it
> at
>   > idle with the A/C blower on high speed for five (5) minutes to
> optimize
>   > the amount of oil in the compressor.
>   >
>   > 2) Recover all R-12 refrigerant from the vehicle's A/C system.
> Evacuate
>   > the A/C system for at least thirty (30) minutes to a vacuum of 29 in.
> Hg,
>   > using R-12 equipment, to remove as much R-12 as possible from the
> residual
>   > mineral oil.  Don't just dump the old R12 into the air.  If you really
>   > don't want it, at least let a service station vacuum it out.  They
> will
>   > generally take it very happily, as it is quite expensive, and you
> won't be
>   > polluting.
>   >
>   > 3) Remove the compressor from the vehicle, noting the placement of all
>   > shims and washers, and the routing of hoses and wires.
>   >
>   > 4) Remove the compressor oil plug and then drain as much mineral oil
> as
>   > possible from the compressor body.
>   >
>   > 5) Drain mineral oil from the cylinder head suction and discharge
> ports
>   > while turning the shaft with a socket wrench on the clutch armature
>   > retaining nut.
>   >
>   > 6) Remove the existing R-12 receiver-drier or accumulator-drier from
> the
>   > vehicle and discard.  Allow as much oil as possible to drain from the
> A/C
>   > hoses. Blowing them out with an air gun on moderate pressure is okay.
>   > Back-flushing the lines is recommended. Plain old mineral spirits
> swished
>   > around in the compressor and backflushed through the lines will remove
>   > contaminants and old mineral oil. Make DARN, DARN sure that you get
> ALL of
>   > it out of the system, and I do mean ALL of it.  Mineral spirits can be
>   > explosive, but a great many a/c shops still use this technique to
> great
>   > effect. I would recommend drying everything out with clean dry air
> from a
>   > compressor for quite a while (hey, air is free, right?) Commercial a/c
>   > flushing chemicals are also available which will do the same while
> being
>   > safer, but they can be pricey.
>   >
>   > 6) Replace any O-rings on the receiver-drier or accumulator-drier
> joints;
>   > check and replace other O-rings that have been disturbed. You really
>   > should replace them with the new green ones -- they work very well for
>   > both R12 and R134a.  If you are converting to R134, new reports
> suggest
>   > that you do -not- need to change all of the O-rings to different
> materials
>   > as thought earlier. However, I would recommend changing anywhere you
> have
>   > disconnected a joint, just to help seal better. They're cheap anyway,
> and
>   > cheaper than having to do it again because of a leaky seal.
>   >
>   > 7) Replace the accumulator-drier with a new R134a compatible unit
> which
>   > contains XH7 or XH9 desiccant. Make sure that you get one with "XH7"
> or
>   > "XH9" dessicant, not "XH5" -- there should be a sticker on it stating
> as
>   > such.  XH7/9 works just fine with R12 and is necessary with R134's
> Ester
>   > or PAG oils.  As a cross-reference, a 1986 Corvette accumulator-drier
> is
>   > perfect. Factory Air brand part number 33191 dryer is ideal, and runs
>   > about $55 at AutoZone.
>   >
>   > 8) While you have the accumulator-drier removed, now is a good time to
>   > replace the orifice tube.  Always replace it 'just because'.  The type
>   > used on the DMC is just a standard "white" GM orifice tube used for
> many
>   > years on many GM models, and the cost is less than $2. (Any parts
> counter
>   > person should know what you mean when you ask for one). There are some
>   > newer variable orifice tubes claiming to work better with R134a, but I
>   > have not read very much about them, and I'm a little wary of their
> claims.
>   >
>   > 9) Perform any necessary repairs to the compressor or A/C system.
>   >
>   > 10) Using the original refrigerant oil quantity specification, add
> [INSERT
>   > QUANTITY HERE] ounces of Ester oil to the compressor. Ester oil is
>   > preferable to PAG in a retrofit, as it will mix fairly well with any
>   > remaining mineral oil.  It was originally thought this was not the
> case,
>   > but consensus nowadays is that they mix satisfactorily.  Ester is also
>   > less corrosive than PAG.  As an additional benefit, R-12 will also
> work
>   > with Ester should you ever wish to convert back.  If you follow these
>   > guidlines, all you would need to do to revert to R-12 is completely
> vacuum
>   > all R134 out of the system and then simply reinstall R-12.
>   >
>   > 11) Replace the compressor oil plug O-ring with an new O-ring.
>   >
>   > 12) Reinstall the compressor oil plug. The plug seat and O-ring must
> be
>   > clean and free of damage. Torque the plug to 11-18 ft lb (15-25 N m,
> 150-
>   > 250 kgf cm).
>   >
>   > 13) Change any seals at the compressor ports to new seals.
>   >
>   > 14) Reinstall the compressor to the A/C system, paying close attention
> to
>   > the placement of shims and washers from step #3.
>   >
>   > 15) Disable the R-12 service fittings to prevent any refrigerant other
>   > than R134a from being used. You do this by permanently installing
> R134a
>   > quick-connect service fittings to the A/C system.
>   >
>   > 16) Vacuum the system for AT LEAST forty-five (45) minutes to a vacuum
> of
>   > 29 in. Hg once the lines are cleaned, the new drier installed, the
> correct
>   > amount of Ester has been poured in the compressor body, and the whole
>   > system is ready to go. Harbor Freight makes a cheapy high-vac pump for
>   > $15. You can hook this up to a spare R134 can adapter hose ($5) to
> make
>   > the correct fitting for attaching to the car. And yes, you MUST
> evacuate
>   > the lines. This is the most common mistake people have in
> retrofitting. If
>   > you don't get that vacuum down in the system, there is no way the air
> is
>   > going to blow very cold.
>   >
>   > 17) Charge the A/C system with R134a. Generally, about 5% (by weight)
> less
>   > than the R-12 charge amount is required. That means just a little over
> 2
>   > pounds for a DMC.
>   >
>   > 18) Check the A/C system operating parameters. The system should
> function
>   > correctly within acceptable limits of temperatures and pressures --
> this
>   > will ensure that the correct amount of R134a has been charged.  I
>   > purchased at a small R134 gauge at Pep Boys for less than $5.  It
> looks
>   > much like a tire pressure gauge.  It tells you the system pressure in
>   > terms of low/good/high/danger. Likewise, they have a small & cheap
> "meat"
>   > thermometer that will tell you vent temps inside the car.
>   >
>   > 19) Replace all R-12 compressor labels with retrofit labels per SAE
> J1660
>   > in order to provide information on the R134a retrofit which has been
>   > performed.  In other words, you really should put a sticker on there
> that
>   > says it's R134a.  The recommended places are on the compressor and the
>   > accumulator.
>   >
>   > Additional notes:
>   >
>   > - In extreme circumstances when expected cooling performance cannot be
>   > achieved and high discharge pressures are experienced, it may be
> necessary
>   > to add more condensing capacity to the A/C system.  I believe PJ Grady
>   > sells a larger capacity condenser for our cars.
>   >
>   > - Sanden has the service manual up for our compressors online at
>   > http://www.sanden.com/support/servicemanual/index.html
>   >
>   > -Dave
>   >
>   >   ----- Original Message -----
>   >   From: Travis Goodwin
>   >   To: 'DMCForum@xxxxxxxxxxxxxxx'
>   >   Sent: Monday, March 15, 2004 12:46 PM
>   >   Subject: [DMCForum] Here it comes again... the R134 conversion
>   >
>   >
>   >   I desperately need to do this before Pigeon Forge. Last summer I was
>   > lucky
>   >   that I didn't have to drive it much since the engine was dismantled.
>   > This
>   >   year is a different story.
>   >
>   >   Bill, I know you're the man when it comes to this. Any advice on
> where
>   > to
>   >   start?
>   >
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