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

[Bob]

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



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