[Supras] No AC on 86.5 MkIII w/ R134A conversion

[Jim Wooden]

Bob:

Thanks!!!

I suspect I have lost a bit of freon system is now undercharged.
I have never replaced any of the sytem components other than o-rings 
in all the years I've owned it (since new).
So maybe it is time to suck out the charge, replace the dryer & 
expansion valve if I can locate it ;-)  and do the gasket on top of 
the compressor & all the o-rings I can find and recharge it based on weight.

When I did the original conversion there was a chart (that I'll have 
to find) that indicated correct amount of R134a vs. R12 charge.

Odd about painting over the sight glass.. mine does have a light film 
on the inside but is still very "readable" ....
I DO understand the concerns about it no longer a reliable indicator.

Jim


At 11:12 PM 3/28/2008, Bob wrote:
>I did this conversion a couple of years ago and I too have a small leak.
>
>R134a molecules are smaller and are more prone to small leaks.  If your
>friend has a good sniffer or he installed dye you might be able to find the
>leak.
>
>Did you replace the top plate seal on the compressor?  If you have to
>recharge the system I would consider replacing all the o rings that are easy
>to get to and if you see a lot of oily buildup on a hard to reach one
>consider that also
>
>The expansion valve failed on my 91 Mr2 and it was easy to change.  If it is
>in a similar location on the Supra spend the $30 and replace it.  Better to
>do it now than have to watch the R134a disappear.
>
>As to the sight glass...  Toyota tells you to block it out.  I won't argue
>with anyone else on the list I will just post the quote
>
>Mineral based R-12 oil remains and circulates in the A/C system and does not
>dissolve in R134a refrigerant. This results in a cloudy appearance at the
>sight glass making it impossible to judge the refrigerant charge amount by
>using the sight glass method. To prevent misdiagnosis on retrofit vehicles,
>apply black paint to the sight glass on block- joint (FF) type
>receiver/dryers. Union-nut joint (BAG) type retrofit receiver/dryers are
>manufactured without a sight glass.
>
>The Toyota instructions are here,
>
>http://www.cygnusx1.net/Supra/TechTips/R134a.aspx
>
>This is the actual bulletin from Toyota about retrofitting that I got for
>him from one of the programs I bought
>
>Bob
>
>
>
>
>
>
>
>-----Original Message-----
>From: supras-bounces at supras.com [mailto:supras-bounces at supras.com] On Behalf
>Of Jim Wooden
>Sent: Friday, March 28, 2008 9:02 AM
>To: Supras at supras.com
>Subject: [Supras] No AC on 86.5 MkIII w/ R134A conversion
>
>
>Well some years back I converted my AC to the R134A as, at the time,
>R12 was very expensive and I had some leaking o-rings that required
>disassembly of the system.
>
>On the advice of a mechanic buddy that had done a number of these
>conversions we did the "simple" conversion which consisted of adding
>PAG oil and "special additives" via a kit from Quest then recharged
>with recommended amt of R134A
>
>Worked fine for two years then just didn't seem nearly as cold any more.
>I took it back to him and, finding no serious leaks, he just hooked
>up the AC machine pumped it down and loaded a fresh charge.
>Well... its two years later AGAIN, and although there is still some
>charge in the system (sight glass shows pretty full) I get ZERO cold air.
>
>I have heard the R134A cars (esp. the conversions) are much more
>sensitive to being low on charge, and that could be the case here...
>
>Does anybody have the recommended high-side/low-side pressures for a
>MkIII R134A conversion handy?
>
>Other suggestions appreciated also  ;-)
>
>Thanks,
>Jim W.
>original owner 1986.5 MkIII
>
>
>
>_______________________________________________
>Supras mailing list
>Supras at supras.com
>http://supras.com/mailman/listinfo/supras_supras.com
>
>
>--
>No virus found in this incoming message.
>Checked by AVG.
>Version: 7.5.519 / Virus Database: 269.22.1/1347 - Release Date: 3/27/2008
>7:15 PM