More AC Stuff

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dick kennedy

New member
Jun 1, 1998
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I'm nearly ready for final hookup of the second evap then will pump down
and recharge.

I've got new hoses and am considering R-134 instead of R-12 or a
substitute. It's much cheaper and more readily available. I've got R-12
available but it's so valuable that I hesitate to use it. Has anyone else
done this switch and if so what were the results? If it's a wash I'll do it.

If I'm going to do this I need to change to esther oil and need to purge
all the old oil possible. That being said do I need to remove the
compressor and dump the oil from it? I've also heard of flushing the system
with mineral spirits or some other solvent. I'm looking for experience or
information here. One web site I've been to says to just add new oil and
put in the R-134.

I know the recommendations and opinions on this have changed since we first
got saddled with 134. Is there a concensus on what is necessary and what
constitutes best practice?

Dick
 
>I'm nearly ready for final hookup of the second evap then will pump down
>and recharge.
>

Dick,

which evap did you install and where? I need to rebuild my system in the
next 3 weeks and want to add a second evap unit somewhere near the front of
the cab area.

Jim Bounds says under the fridge is a good place too. I'm not certain about
giving up that space though.

Henry
 
Dick,

Have you checked at http://www.aircondition.com/wwwboard/index.htm ?
Several guys who hang around there are in the automotive AC business and
seem to provide some good answers.

Also have a lot of changeover discussions in the archives at this site.

Please let us know what you find out about R-134 and how well your new
system works.

Don Miller
Shenandoah Valley of Virginia

> I'm nearly ready for final hookup of the second evap then will pump down
> and recharge.
>
> I've got new hoses and am considering R-134 instead of R-12 or a
> substitute. It's much cheaper and more readily available. I've got R-12
> available but it's so valuable that I hesitate to use it. Has anyone else
> done this switch and if so what were the results? If it's a wash I'll do
it.
>
> If I'm going to do this I need to change to esther oil and need to purge
> all the old oil possible. That being said do I need to remove the
> compressor and dump the oil from it? I've also heard of flushing the
system
> with mineral spirits or some other solvent. I'm looking for experience or
> information here. One web site I've been to says to just add new oil and
> put in the R-134.
>
> I know the recommendations and opinions on this have changed since we
first
> got saddled with 134. Is there a concensus on what is necessary and what
> constitutes best practice?
>
> Dick
 
Don,

I had this site bookmarked about two years ago. My problem is that there's
just not enough hours in the day to read all that I need to then I don't
remember all that I do read. I think I spent a lot of time at this site
when I first found it.

I really need the one page executive summary that doesn't use too many big
words.

Dick

>
>Dick,
>
>Have you checked at http://www.aircondition.com/wwwboard/index.htm ?
>Several guys who hang around there are in the automotive AC business and
>seem to provide some good answers.
>
>Also have a lot of changeover discussions in the archives at this site.
>
>Please let us know what you find out about R-134 and how well your new
>system works.
>
>Don Miller
>Shenandoah Valley of Virginia
>
>
>
>
>> I'm nearly ready for final hookup of the second evap then will pump down
>> and recharge.
>>
>> I've got new hoses and am considering R-134 instead of R-12 or a
>> substitute. It's much cheaper and more readily available. I've got R-12
>> available but it's so valuable that I hesitate to use it. Has anyone else
>> done this switch and if so what were the results? If it's a wash I'll do
>it.
>>
>> If I'm going to do this I need to change to esther oil and need to purge
>> all the old oil possible. That being said do I need to remove the
>> compressor and dump the oil from it? I've also heard of flushing the
>system
>> with mineral spirits or some other solvent. I'm looking for experience or
>> information here. One web site I've been to says to just add new oil and
>> put in the R-134.
>>
>> I know the recommendations and opinions on this have changed since we
>first
>> got saddled with 134. Is there a concensus on what is necessary and what
>> constitutes best practice?
>>
>> Dick
>
>
>
>
>
 
>Henry
>
>PLEASE let me give you a lesson on air con design. First hot air rises
>thats why hot air balloons go up in the air. The same thing happens in
>your coach. Your roof air works so well because it sucks in the hottest
>air and puts out cold air which falls through the hot air. You can put out
>cold air all day on the floor and it aint going to break up the hot air
>balloon on the ceiling---that stuff is going to stay there. If you look at
the
>fix for the dash air that GMC tried it points the air up trying to break up
>the hot air on high. It still does not work all that well. You have to suck
>the hot air in to get an AC to work well. If you want a second evap to work
>as well as your roof AC put it where the roof AC is------on high. I am just
>trying to help---not be critical----its just a problem I have.
>

No problem for me - I can ignore good advice just fine!

Seriosly, I have looked at a lot of alternatives on the A/C front. A friend
is in the process of putting a big truck headliner A/C evaporator & fan in
the front of his GMC. It looks pretty good and it probably will work quite
well. The big problem thta I see is running the freon lines. My friend had
to cut the side aluminum frames a bit to run the hoses up on the passenger
side. They're too big to run down the window center post. I guess that I
could build a "wart" to cover them and run them on the inside of the frame
(inside the coach).

I'll let you know what I do and how it works out.

Henry
 
Henry,

Run 'em on the outside and sell it as a feature! Everybody will see you
coming and be jealous.

Seriously, I think anyone doing a major restoration should consider some
type of overhead mounting or ducting. Over the drivers head looks like a
great out of the way place but for now my under the couch mounting will
have to do.

Dick

>>Henry
>>
>>PLEASE let me give you a lesson on air con design. First hot air rises
>>thats why hot air balloons go up in the air. The same thing happens in
>>your coach. Your roof air works so well because it sucks in the hottest
>>air and puts out cold air which falls through the hot air. You can put out
>>cold air all day on the floor and it aint going to break up the hot air
>>balloon on the ceiling---that stuff is going to stay there. If you look at
>the
>>fix for the dash air that GMC tried it points the air up trying to break up
>>the hot air on high. It still does not work all that well. You have to suck
>>the hot air in to get an AC to work well. If you want a second evap to work
>>as well as your roof AC put it where the roof AC is------on high. I am just
>>trying to help---not be critical----its just a problem I have.
>>
>
>No problem for me - I can ignore good advice just fine!
>
>Seriosly, I have looked at a lot of alternatives on the A/C front. A friend
>is in the process of putting a big truck headliner A/C evaporator & fan in
>the front of his GMC. It looks pretty good and it probably will work quite
>well. The big problem thta I see is running the freon lines. My friend had
>to cut the side aluminum frames a bit to run the hoses up on the passenger
>side. They're too big to run down the window center post. I guess that I
>could build a "wart" to cover them and run them on the inside of the frame
>(inside the coach).
>
>I'll let you know what I do and how it works out.
>
>Henry
>
>
>
 
You guys are confusing me again. (Yea, I know, not hard.)

As far as I can tell, our '76 has the original dash a/c using R12. Based on
snips from earlier posts, I've been prepared to change over to either
FRIG-C (Pennzoil) or AutoFrost, Hot Shot, FREEZONE or FREEZE 12 (unknown
mfg.) when the R12 needed replenishing because these substitutes reportedly
need no system modification (uses same hoses, etc.)

The recent "More AC Stuff" thread seems to imply that R-134 is also an
acceptable substitute. I thought that new barrior hoses and some new seals
were needed to use R-134. Am i right?

Also, is it true that FRIG-C, AutoFrost, Hot Shot, FREEZONE or FREEZE 12
can be substituted for R12 without changing hoses, etc?

Just trying to be prepared,

___________
Dave (& Dege), '76 Royale /_][__] [_] | "SR JAMES"
Santa Barbara, CA *0-------OO--* (our hobby)
 
Dave,

It's my understanding that R-134 is a smaller molecule than R-12 so it
leaks through hoses faster. All of the R-12 substitutes are blends so I
assume they also contain some light molecules which are also prone to
leakage. This selective leakage can lead to undesirable operation as the
system ages. My opinion here is a little different than these guys claim
and I'm speculating here since I've not spent enough time to be expert. So
take it at face value and form your own opinion. Another key point is that
R-134 is available to anyone and the others are not.

Someone told be that the large suction line on the old hoses is the
dominant source of leakage and the other hoses are negligible. There's a
web site I was at that says experience had shown that the oil used was
effective in sealing the pores and that changing hoses wasn't necessary. I
took this last one with a grain of salt. In fixed AC work most all the
connections are brazed and there are no rubber seals. It seems these are
built to much more stringent leakage standards. I think it's been normal
for me to add a can of freon per year to all of the AC systems that I've
owned since the sixties so I think some leakage is considered normal by
most auto AC guys.

I've heard a mixed bag on 134 conversions. Some claim it's less effecient
and others say it is the same. I believe it does tend to run at higher head
pressures and stresses the system a little more. Some say that a 134 system
should have a larger condenser to function equally. Early reports were
that 134 required extensive system modifications but current practice seems
to be just add the right oil and put it in and go. I don't know how good
the science behind this is but there seems to be more or less a consensus
that new Barrier hoses and O rings will be good enough.

My system was charged twice with Auto frost last year. The first time I
blew a hose on the first day. The second charge leaked out over the winter
even though it had been carefully leak checked; I later found I'd left out
an O ring when I put the hose in. Now all my hoses are the new barrier
type except for the two small ones in front that I couldn't locate and all
the O rings have been replaced with the barrier type so 134 is a viable
option for me.

Last I knew wholesale cost of R-12 was around $15 per pound while R-134 was
around $3. I don't know prices on the substitutes. Without looking it up I
think I'm talking about 5 pounds with my new rear evap so that's a big
difference.

I'm planning to leave for yellowstone without the GMC sometime yet this
week. My minivan is getting a new transmission so don't yet know when I'll
get it back. A close friend's daughter was in a serious wreck near Fargo,
Nd and is in critical condition there so I intend to leave as soon as
possible and go there to lend moral support for a few days.

The GMC is close to being finished but I probably won't get back to working
on it until mid July. Assuming I still remember how to put it back together
I'll be able to provide a full report then.

This explains some of the why behind what I'm doing. Hope it helps.

Dick Kennedy

>You guys are confusing me again. (Yea, I know, not hard.)
>
>As far as I can tell, our '76 has the original dash a/c using R12. Based on
>snips from earlier posts, I've been prepared to change over to either
>FRIG-C (Pennzoil) or AutoFrost, Hot Shot, FREEZONE or FREEZE 12 (unknown
>mfg.) when the R12 needed replenishing because these substitutes reportedly
>need no system modification (uses same hoses, etc.)
>
>The recent "More AC Stuff" thread seems to imply that R-134 is also an
>acceptable substitute. I thought that new barrior hoses and some new seals
>were needed to use R-134. Am i right?
>
>Also, is it true that FRIG-C, AutoFrost, Hot Shot, FREEZONE or FREEZE 12
>can be substituted for R12 without changing hoses, etc?
>
>Just trying to be prepared,
>
>
> ___________
>Dave (& Dege), '76 Royale /_][__] [_] | "SR JAMES"
> Santa Barbara, CA *0-------OO--* (our hobby)
>
>
>
 
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