[DML] Re: AC Rubber tubing

["Jim Reeve" <dmc6960@xxxxxxxxx>]

Well, if all the previous owner spent was $34, it certainly wasn't
done properly.

First and foremost, the R12 oil is still in there.  A no-no for the
long term, but usually shows no ill effects for the near term.  The
oil is critical for the compressor operation. Incompatible oil is said
to gum up and eventually ruin the compressor. For now, if your
compressor and clutch operate fine, I wouldn't bother changing them.
Have an A/C shop do a flush when you have the remaining 134a
evacuated. Not sure what it involves, but it is supposed to get the
old oil out. My compressor clutch was failing, and I also had leaks in
a few different spots on it. (How do I know? Read on...)

The hoses themselves probably arn't the source of your current leak. 
The old A/C hoses dont tend to leak 134a if they have been used in the
past by R12.  They would leak if you put in brand new (old) R12 hoses
and charged with 134a.

The condensor is probably ok and doesn't need replacing, but it may be
full of bugs, dirt, road-grime, etc. after 25 years reducing its
effectiveness. I chose to replace mine with my conversion since I
needed a new radiator anyways, then while I was at that, might as well
replace my cooling fans too. I bought Toby's new low-power high-flow
fans, can't wait to turn them on! The higher airflow not only
increases the radiator's effectiveness, it also increases the A/C's
effectiveness.

Next comes the high pressure switches.  They arn't critical for normal
function, but are a nice safety feature incase of overcharge, stuck
compressor, or failed cooling fans.  John Hervey's new hoses dont have
ports for these, nor on the new condensor (like some D's), yet he
still sold me a new high pressure switch and relief valve, need to
talk to him about that.

The Orifice tube (in the high pressure inlet for the evaporator)
should be replaced if you do the high pressure short line, but it
wouldn't be critical if you didn't.  Since 134a has less cooling
capability, a new type of orifice tube, called a Variable Orifice
Valve or Smart VAV has been developed to assist performance.  If you
do replace it, replace it with one of these.

The Evaporator is the most difficult part to replace.  Thankfully, it
is the least necessary to replace.  You need to be carefull
disconnecting the lines to it to make sure you dont twist its metal
tubes and cause a leak.  Me being super thourough with my rebuild, I
removed mine and cleaned it out.  Junk and debris get in through the
fresh air intake and plug it up.  Back in 2001 I was able to
significantly clean it out and increase airflow by reaching my arm in
through the blower motor opening and pulling out gunk. This time I
wanted it completely clean so I simply (or rather not-so-simply)
removed it.

Now comes the Accumulator/Dryer.  This is where the excess refigerant
and oil is stored in the system. It also contains a desiccant to
remove stray moisture from the system.  This should certainly be
replaced if you do nothing else. The low pressure cycling switch is
also attached directly to this.  I have observed a moderate failure
rate with this part, so I would also recommend replacing it.

Now, for those who kept reading to find out how I knew about certain
leaks, here it is.  I had no dye in my old system. Didn't need it.  I
watched for rapid dirt and grime buildup on my A/C components.  When
there is a very small leak, the escaping refigerant will take a little
of the oil with it. This will stick to the spot its leaking from, and
cause it to get dirty much quicker than other parts. I had 3 leaks in
my previous system. Two on the compressor (O-rings for the high/low
pressure line connections [repairable with new O-rings], and one on
the weep seal for the clutch shaft [not repairable]), then also a leak
on the high pressure line connection to the evaporator.

Other things to note, on ANY connection that is taken apart, the
O-ring should be replaced with a 134a compatible GREEN O-ring. It is
designed for it. John Hervey's new hoses have the green O-rings on
them. The only one I had to buy was for the evaporator/accumulator
connection.

One more reminder to make sure your long high-pressure line is CLEAR
of the steering shaft!!!  This goes for those installing new hoses,
and those who have never touched their A/C systems! You dont want
rubbing which WILL blow the hose. I personally know TWO Delorean
owners this has happened to.

Make sure you have 19mm, 22mm, 27mm, and 32mm wrenches.

Jim Reeve
MNDMC - Minnesota DeLorean Club
DMC6960

--- In dmcnews@xxxxxxxxxxxxxxx, "sweetp01569" <paul.sweet@...> wrote:
>
> Thanks for the great replies.  I didn't do the conversion.  It was 
> done by the previous owner in March of 2004 (about a year before I 
> bough the car).  The record shows he bought a $34 R134A conversion 
> kit.  This doesn't sound like he replaced any major parts, does it?  
> How extensive is a "kit"? I think I should probably change the tubes 
> and major components that I am able to, then bring it to the shop 
> for final tweaking and refilling.  Is that reasonable, or are there 
> other items to be aware of when replacing components?
> 
> Thanks,
> 
> Paul
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "Jim Reeve" <dmc6960@> wrote:
> >
> > The spliced lines are quite nice for ease of install.  Andy is 
> right
> > that the hardest part is getting the low pressure line through the
> > frame by the gas tank (which really wasn't that hard).  It helped
> > having Andy assist me, in that I could bend down the frame slightly
> > (not a permenent bend, just a flex) and guide the end over the tank
> > plate nuts while Andy actually pushed it through.  It can also be
> > difficult to separate the nuts and the lines.  You need to spend 
> $75
> > on a 32mm, 27mm, and 22mm wrench.  19mm is also necessary but I
> > already had one of those.  There is not much room to work the 
> wrenches
> > but it is possible (hey, they got them on there didn't they?). On 
> the
> > first car I did a few years ago, I could not separate the high
> > pressure line from the evaporator.  I got the nuts apart, but the
> > lines would not disconnect.  With more time they probably could 
> have
> > come apart, but I didn't have any then.  My car which I'm in 
> progress
> > with was no problem.  If your doing all this, replace the 
> accumulator
> > and orifice tube as well (unless you did that with your original
> > conversion).
> > 
> > Other misc. notes....
> > 
> > Be sure to keep the main high pressure line away from the steering
> > shaft.  Many owners have had sudden AC failure when this hose was 
> warn
> > through by the shaft.
> > 
> > Also, John Hervey has not been as responsive as he has been in the
> > past.  When I made my original order almost everything came as it
> > should.  I emailed him many general questions about the parts and 
> two
> > that were missing, no responce.  I called him a few times then
> > eventually got through to him to get one of the parts that didn't
> > arrive, but I still dont have the other one yet.
> > 
> > When I arrive in Chicago, every component in my A/C system will be
> > brand new except for the evaporator, which I removed and throughly
> > cleaned.
> > 
> > Jim Reeve
> > MNDMC - Minnesota DeLorean Club
> > DMC6960
> > 
> > 
> > --- In dmcnews@xxxxxxxxxxxxxxx, "sweetp01569" <paul.sweet@> wrote:
> > >
> > > I had my R134A recharged last summer, and the AC felt nice and 
> cold at 
> > > that time  This year, I really don't feel any cold air coming 
> through 
> > > and the compressor just turns on and off for about a second 
> every 5 
> > > seconds or so.  I suspect my charge is gone.  I read that older 
> R-12 
> > > rubber tubing (I suspect those that run under my car are 
> original) 
> > > will actually let the R134A pass through the molecules of 
> rubber, 
> > > resulting in a slow leak over the winter.  Is this true?  If so, 
> is it 
> > > worth investing in Special T's spliced tubing (I don't have time 
> or 
> > > patience to lift the car body to replace with whole sections) 
> and 
> > > replacing the long runs under the car?  Can I just replace them 
> easily 
> > > myself, or do I need an AC shop to evacuate any remaining R134A 
> for 
> > > safety/environmental reasons - or is there not enought to worry 
> about 
> > > if I open and replace the tubing before I bring to an AC shop to 
> > > recharge?  Any advice on this subject is appreciated.
> > > 
> > > Thanks,
> > > 
> > > Paul
> > > Vin 10944
> > >
> >
>










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