Re: Ice, Ice, Ice, Baby: Milano AC retrofit

[Mark Denovich <mark@domain.elided>]

I was hanging my head in shame today when I drove to work... The AC 
wasn't working.   When I got home I realized the compressor wasn't 
engaging.   Happily I quickly diagnosed a loose fuse holder on the AC 
clutch relay, a little tweaking and I was back in business.

My eagerly awaited response follows:


> First, I'm guessing Mark went simply on the old bubbles in the sight
> glass method as he pretty well points out.
Yes and no.   I first calculated how much ES-12a I'd need to fill the 
system, based on the shop manual which states the AC capacity at 1.98lbs 
(or just about 32oz.) Convienently this works out to just a bit less 
than 2 cans of ES-12a.  As I was adding the last of the second can I saw 
the bubbles go away.   It's pretty clear when it happens.


> In my case, I'll be going from a totally empty AC system on my Alfetta
> GT. I've had the lines to the dryer just dangling there for about five
> years since I've kept the rubber plugs on the 'new' (unused) dryer
> itself. Therefore, I'm very concerned about 'purging' the system first
> before adding refrigerant.
The recommended procedure is to pull a vacuum on the system to check for 
leaks, to remove any water present in the system (and anything else for 
that matter.   My system had still had R-12 in it, which I had removed.


> Mark, I'm a little vague on the removal of the existing 'valve core'. Is
> it on the compressor or the adapter / filling unit? And if you remove
> the valve core, what do you put in it's place? Basically I'd like to
> have everything in front of me when I start.
The R-12 fittings use a schraeder style port/valve (just like a car 
tire.) The little nipple thing in the middle is the tip of the valve 
core.   They make a cheap little tool for unscrewing valve cores.  You 
need to emove the one from your existing low pressure R-12 fitting, 
because the LP R-134a adapter fitting has it's own valve core.


> I also removed and saved (most) of the oil in the compressor. What was
> saved measures 55 ml. How do I know how much oil to add? I'm assuming it
> comes in pressurized cans. How many oz. is 55 ml?
I have no idea how much oil you need.   But 55ml is 1.86oz

> I've been told the 'new improved' R-134a will work in older units
> without having to change seals, hoses, etc. While I've not checked it
> out, gather it is easily available. Should one not use it because it
> actually does harm seals, etc. or because it really doesn't cool all
> that well, or is it in fact almost as good as ES-12a and will work fine?
I think it's not that R-134a harms seals, it's just that it leaks really 
easily.  I think R-134a kits now include goo to help seal the system 
from the inside.   Factory and high quality retrofits use special 
barrier hoses and special seals to combat leakage.

I believe it's a thermodynamic fact that HC based refrigerants are 
superior to R-134a (sorry I don't have a good reference for this, but 
have seen it quoted in many different sources.)

	--Mark
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