[V6-12v] ac refrigerant question

[Elliott Potter]

On Tue, 30 Mar 2004, Tim Crift wrote:

> I have charged my '95 90Q through the high pressure port without difficulty.
> The Bentley is necessary for this as well as a good set of gauges with an
> integrated charge line.  No boiling of cans or the like.  Lookup the static
> pressure that the system should have based on ambient temperature and fill
> the system until the gauge reads that pressure.  The car should not be
> running when you do this and it helps to keep the charge can upside down so
> liquid Freon enters the system as it expands.

Could you elaborate on this a bit?  You just plugged the bottle in
through the manifold gauges and it worked?  I tried once but couldn't
get the system to take anything out of the bottle.
--
Elliott

> Tim
>
> -----Original Message-----
> From: v6-12v-bounces at audifans.com [mailto:v6-12v-bounces at audifans.com]On
> Behalf Of Elliott Potter
> Sent: Tuesday, March 30, 2004 10:21 PM
> To: Edward Sluis
> Cc: v6-12v at audifans.com; 'Jack Tozzi at Novi Cantori'
> Subject: RE: [V6-12v] ac refrigerant question
>
>
> Most other cars charge through the low pressure port.  I've never
> seen a good explanation for why Audi decided to use the high pressure
> port instead, except that it eliminates confusion over which system (R12
> vs R134a) you have ... if you go to the car with your hose to plug into
> the low pressure port, and there isn't one, you know you're on the wrong
> track.
>
> There is, in fact, a low pressure port - it's under the dashboard,
> behind the climate control fan housing, on top of the ECU, and has the
> low pressure switch screwed in to it.  To get at it, you need to remove
> a kick plate, remove the ECU, then plug it back in sitting on the
> floorboards (since the engine needs to run), then use a special tool (a
> 17(?)mm open-end wrench that's about 3" long) to remove the low pressure
> switch.  Sort of inconvenient.
>
> I've heard of people charging through the high pressure port using those
> cans of R134a from a FLAPS (Todd?), but they boiled the cans first and
> that would make me very nervous.  (I'm not an Audi engineer, but I did
> take a class in thermodynamics my junior year at GT ... had I not
> skipped most of them I might have a different view)
>
> You can take your car to a decent shop and they
> will have the proper equipment to fill the coolant and PAG oil through
> the high pressure port (they don't top off through the low pressure
> port).  If it's just low, they probably won't charge too much either.
> Worth it IMO.
> --
> Elliott
>
> On Tue, 30 Mar 2004, Edward Sluis wrote:
>
> > Just a quick check, I'm not an Audi engineer, but I am an engineer and I'm
> > just wondering:  You said that charging is suppose to be done through the
> > high pressure port, as far as my knowledge of HVAC systems goes it is only
> > recommended to charge through the high side with an approved charging
> > station with the system off and then topping it off on the low side with
> the
> > system on.  If you're a do it yourselfer using the cans, your better off
> > charging on the low side.  I may be wrong but that's what my experience on
> > the design side of things seems to make me think.
> >
> > -----Original Message-----
> > From: v6-12v-bounces at audifans.com [mailto:v6-12v-bounces at audifans.com] On
> > Behalf Of Elliott Potter
> > Sent: Tuesday, March 30, 2004 6:58 PM
> > To: Jack Tozzi at Novi Cantori
> > Cc: v6-12v at audifans.com
> > Subject: Re: [V6-12v] ac refrigerant question
> >
> > On Tue, 30 Mar 2004, Jack Tozzi at Novi Cantori wrote:
> >
> > > Hello All,
> > >
> > > The AC in my 1995 Audi 90 is not delivering cool air this spring.  I
> > haven't
> > > done any troubleshooting to speak of but I can say that the compressor
> is
> > > not engaging when I hit the AC switch. This makes me suspect the low
> > > pressure switch is being tripped.
> >
> > Very often under a low pressure condition the compressor will cycle on
> > and off at least once when you turn it on, unless the pressure is
> > *really* low.  You don't happen to have the automatic climate control
> > (as opposed to the three knob system), do you?
> >
> > > My dilemma is I'm not sure which refrigerant the car is using.  It was
> > built
> > > in 06/94 but was in an front end accident prior to my purchasing the car
> > in
> > > 2001.  Because of the accident, the condensor has been replaced and I
> > can't
> > > find any other place where the refrigerant type is listed.  It seems
> very
> > > likely to me that the car has to have 134a because parts of the system
> was
> > > rebuilt because of the accident, but I'd obviously like to avoid
> > > contaminating the system by adding the wrong refrigerant.
> > >
> > > So, does anyone know for sure what the car originally came with?
> Bentley
> > > was no help, it simply provided service info for both systems.
> >
> > Audi changed to 134a in October 1992, so you're sure to have
> > R134a.  There should be a silver sticker on the back of the hood, on the
> > passenger's side that says so.
> >
> > There's also no easily-accessible low-pressure port on the R134a
> > systems; charging is supposed to be done through the high-pressure port
> > on the front of the condenser.
> > --
> > Elliott
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