R134a retrofit questions?

[John Cody Forbes]

Oh, I forgot to mention:
http://www.es-refrigerants.com/

Highly recomended as an lternative to both 143a and r12.

-Cody Forbes

Kunz, Bob wrote:
> You know after 20+ years for the first recharge that's pretty good.
> My '86 5k lost a little refrigerant over the years and I've just had
> to top it up once so far.  
> 
> There's more to 134a conversion that what you describe on these
> vintage cars. If you actually have a leak, it will get worse since
> R134a is less dense than R12. This could also cause slow leaking
> through the actual hoses. But R134a is a lot cheaper than R12 but IS
> still available with prices coming down. You should replace all seals
> with new ones.     
> 
> Failures (i.e. not as cool) on the conversion are almost always due
> to mineral oil not being completely evacuated. Some system
> configurations will be OK, others not. If oil pools in components it
> will restrict flow and cause inefficiencies. Usually the conversion
> involves flushing the system to remove all mineral oil.    
> 
> Then you should really take the compressor off and drain the
> remaining oil in there. You don't flush the compressor. 
> 
> Having done that you can use PAG oil as opposed to ester which is a
> compromise to let you keep some mineral in there. The correct amount
> of oil in this GM based system is 10.5 oz. You need to distribute it
> some as you close up the system. It won't all fit in the compressor
> anyway, only about 2 oz goes in there.    
> 
> Then of course you need to use a real vacuum pump and get the system
> down below 100 microns, find your assembly leaks. Hold 220 microns
> for an hour to boil off all the water (this would be why you do this
> in the summer as opposed to now - it's easier to get the water out
> when the ambient is hot), then add your refrigerant.    
> 
> Lots of folks have adjusted the evaporator sensor down to just above
> freezing. In high humidity areas this is risky since its purpose is
> to keep the evaporator from freezing. This system is a chill/re-heat
> type so the refrigeration runs to the set temp of the evaporator. If
> you set it low, the compressor will run more. Your choice.    
> 
> Back to your original question... at this point I'd go source some
> R12 and charge it up. You might find that's all you need for the next
> 10 years.  
> 
> --bob
> '86 5Ks Avant
> '02 TTQR
> '06 GTI
> '07 Q7 4.2
> 
> -----Original Message-----
> From: quattro-bounces at audifans.com
> [mailto:quattro-bounces at audifans.com] On Behalf Of Dave Yentema 
> Sent: Wednesday, October 22, 2008 11:03 PM
> To: quattro at audifans.com
> Subject: R134a retrofit questions?
> 
> hey guys, got a couple of questions about converting the ac in my car
> (875kt)
> 
> she has never been retrofitted to 134, and from lack of use 90% of
> the r12 
> is gone, its low to the point that the comp won't even run(I tested
> this by 
> jumping the connectors on the low pressure switch) So after weighing
> out all 
> the options, i've decided that the conversion is my best bet right
> now. 
> 
> I've seen my dad do the conversions before, and whenever he did it
> professionally he would just evacuate the r12, change the fittings,
> drop 
> some ester oil in and charge it up with 134 (Even though this isn't
> the 
> recommended procedure, it always worked) . He knows his stuff with
> AC, does 
> everything the old fashioned way with just the manifold gauges and
> knows 
> exactly what lines to touch, etc. Having him help me on this isn't
> really an 
> option for this.
> 
> This is what I'm picking up:
> 
> -New receiver/drier (from AutohausAZ)
> -134a retrofit kit, not the one with the oil, but its got all the
> fittings 
> and o-rings I'd need (also from autohaus)
> -Polymax2 oil http://www.autoacsource.com/store/coolzone_oil.html
> -Variable orifice
> tubehttp://www.acsource.com/index.asp?PageAction=VIEWCATS&Category=273
> 
> 
> 
> 
> I know that the system holds about 39oz of R12, and it'll take about
> 85% of 
> that with 134, so about 33oz?
> 
> and how much oil does it take? I read somewhere it takes 8oz but i'm
> not 
> sure.
> 
> also, any reason  why I can't do all of this while its getting colder
> outside? or should I wait till springtime to try and fill er up so to
> speak 
> 
> any suggestions would be awesome
> 
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