A/C fun

[Patrick Young]

Patrick's guide to _*dodgy*_ A/C repair (however it works, and
there *should* be no risk of leaking propane or falling Commodes,
however equally Darwinian none the less).

Well, if nothing much useful done this weekend, at least I now
have two *working* and bloody cold vehicle air conditioning systems.

As Diesel Damo noticed yesterday on my vehicle, the gas was
being held in by the plastic cap/rubber washer due to a leaky
Schrader - it didn't actually used to be _that_ leaky :-( Tut Tut
(*not* a good look on my part :-( )

I was also due to help my friend fix the A/C on his Smurf later that
day. This requires removing the gas from mine as I need the R134a->R12
adaptor - more on that later.

Background was my friend with the Smurf lost the gas from his
original 1989 R12 system (therefore compressor not fitted with R134a
adaptors). We regassed with propane some time back and could smell
the propane within the vehicle over a period of time. OK - evaporator
leak that caused the original failure.

Today took it out and took it apart:

http://www.fce.unsw.edu.au/people/py_stuff/tx_valve.jpg

(sorry about picture quality - stuffed right hand, and an
unfamiliar borrowed cam).

Even before taking the TX valve apart, the thin film of
oil was obvious. From the photo the junctions are formed using
O-rings. The discharge (high pressure smaller pipe) had tell
tail oil film from the O-ring outwards.

Obviously, ring needs replaced (although does not appear damaged
in any way - neither do any of the contacting surfaces.

For now, to prove the point at least, silicone rubber was placed
around the outer edges surrounding the existing O-ring. This will
of course all have to come apart again to be done properly and new
parts used - obviously.

The real PITA about the whole thing is my A/C was converted to
R134a which of course didn't work - so went to propane. The fitting
spun up for me to join the R134a adaptor and BBQ bottle hose needs
that R134a adaptor.

His is still the R12 fittings. The PITA is the folk doing my R134a
conversion removed the Schrader from the compressor and mounted it
*in* the 90 degree adaptor. Therefore removing the adaptor means
de-gassing mine (today fixed that by moving the valve back to the
compressor). I can now gas R134a and R12 systems with propane
unbolting that adaptor without affecting mine.

Disclaimer: The following is Darwinian if done incorrectly. It is
probably Darwinian anyway!. *Don't* do this if you are at all
uncomfortable with the idea!. *Don't* do this if you don't
understand how dangerous/inflammable propane (R290) is, or do not
understand it's liquid/gas phases!. *Don't* do this by yourself.

Two people are *required* who both understand the process. Ideally
a third person should be present in case of accident/incident.

Leave windows/doors of vehicle open at all times and overnight
after gassing a system, only attempt this in an open car port or
outdoors - yada yada yada. *NO* sparks, open flames, etc. I am
in *no* way responsible for any injury/death/property damage m'OK?

You should also label the system clearly as containing R290
(propane). This may not even be road legal in your state.

That said,

Got the gassing process down to a fine art now. Screw the hose and
fitting onto the suction side, attach BBQ bottle to hose. With
bottle up the right way and upside down, test for any leaks in the
hose fittings !!!!! soapy water - whatever makes you happy. With
no flames/sparks/etc and engine off, press in the discharge side
valve in order to note gas comes out there and only there (ie: no
major leaks in the system). This stuff has a strong smell, use your
nose and have friend do similar!

Have a friend (who knows what they are about to do) hold the bottle and
invert. Spin compressor by hand to make sure it spins freely. Start
engine - (this is where it starts getting iccky). Initially bridge
A/C clutch to 12V (it won't be operating due to lack of pressure in
the system).

Have friend turn on valve *very* slightly - _slightly_, they have to
understand this does not mean lock up the compressor!. Observe sight
glass for liquid (the compressor will suck this through the valve *very*
quickly from the propane tank pressure - no need to somehow compress
the valve to make up for lack of tank pressure as I thought before).

As the bubbles go from the sight glass, ask friend to turn off the
propane _right now_. Adjust slightly more propane so bubbles
appear/go when the compressor cycles as per it's sensor/amplifier
circuit.

None of this is correct procedure, ideally vacuum pump, gauge set is
required. System should be checked for proper pressure, opened systems
should be vacuumed, etc and so forth.

[John_H]

Patrick Young wrote:

>
>As Diesel Damo noticed yesterday on my vehicle, the gas was
>being held in by the plastic cap/rubber washer due to a leaky
>Schrader - it didn't actually used to be _that_ leaky :-( Tut Tut
>(*not* a good look on my part :-( )

Why not a brass one?... Robinair brass caps are cheap and readily
available from refrigeration suppliers such as Actrol or Lovelocks as
R22 uses the same fittings as R12. With a brass cap you can safely
leave the valve until next time around.

>
>Have a friend (who knows what they are about to do) hold the bottle and
>invert. Spin compressor by hand to make sure it spins freely. Start
>engine - (this is where it starts getting iccky). Initially bridge
>A/C clutch to 12V (it won't be operating due to lack of pressure in
>the system).

No need to invert the bottle, start the engine, or to use a helper
(inverting the bottle probably increases the risk of a slug of liquid
locking the compressor).

Simply connect the cylinder, right way up with the engine stopped, and
feed the suction side until the system reaches bottle pressure, which
will be around 800kPa (which is sufficient to turn on the low pressure
switch -- ie there's no need to bridge it).

Turn off the cylinder and start the engine with the throttle set to
around half revs and the a/c on high fan and the doors open (to
discourage the sytem from cycling during top up). There should be
bubbles in the sight glass indicating the system is working and oil is
circulating.

Crack the valve ever so slightly and watch the sight glass until the
bubbles disappear. Cease adding gas as soon as they do, or if the
system cycles off on the thermostat.

The only critical part is the topping up with the engine running.
It's a lot simpler, and safer, with gauges as it allows you to monitor
the low side pressure to ensure that you won't create a lockup (I
normally keep it below 600kPa during top up). Proceed slowly in the
absence of gauges for the same end result.

>
>None of this is correct procedure, ideally vacuum pump, gauge set is
>required. System should be checked for proper pressure, opened systems
>should be vacuumed, etc and so forth.

I wouldn't gas any system without evacuating it, however judging by
some of the vacuum pumps I've seen and the time for which they're
connected half the a/c trade may as well not bother.

You can also buy liquid line filter/driers with ¼" male flare
connectors from any commercial refrigeration parts supplier. I use
one in series with the gas bottle since the stuff sold for fuel isn't
likely to be particularly clean or dry. Cap the filter between uses,
and they're also cheap enough to replace often.

Gauges are absolutely essential to faultfinding a system -- you might
just get lucky if there is no fault. :)

--
John H

[kevcat]

> You should also label the system clearly as containing R290
> (propane). This may not even be road legal in your state.

I saw a video done by some people who wanted to start using propane in
car A/C but QLD Transport said no
too risky, they say, might catch fire in a crash

so these people contacted the guy who runs Dangerous Goods Training at
Beenleigh, he looked at the the idea and said yes it would be safe
so they made a video
3 of them sitting in a car(XF Falcon sedan) and sitting on the centre
console was a burning candle
they had the car running and had a valve inside to imitate a ruptured
pipe
then they opened the valve so all the gas entered the cabin
..
..
..
nothing
just the smell of gas


the area inside the cabin is way to small for the amount of gas to
ignite, too rich

QLD Transport still said no

but I bet there are plenty of cars getting about with propane in their
A/C
hell of a lot cheaper and is just as/more efficient as any of the other
gases used
just that it is quite flammable

Kev

[Patrick Young]

John_H wrote:

> Patrick Young wrote:

>>As Diesel Damo noticed yesterday on my vehicle, the gas was
>>being held in by the plastic cap/rubber washer due to a leaky
>>Schrader - it didn't actually used to be _that_ leaky :-( Tut Tut
>>(*not* a good look on my part :-( )

> Why not a brass one?... Robinair brass caps are cheap and readily
> available from refrigeration suppliers such as Actrol or Lovelocks as
> R22 uses the same fittings as R12. With a brass cap you can safely
> leave the valve until next time around.

Very true.

>>Have a friend (who knows what they are about to do) hold the bottle and
>>invert. Spin compressor by hand to make sure it spins freely. Start
>>engine - (this is where it starts getting iccky). Initially bridge
>>A/C clutch to 12V (it won't be operating due to lack of pressure in
>>the system).

> Simply connect the cylinder, right way up with the engine stopped, and
> feed the suction side until the system reaches bottle pressure, which
> will be around 800kPa (which is sufficient to turn on the low pressure
> switch -- ie there's no need to bridge it).

Didn't happen for me on either vehicle, I tried that. I was also a
bit paranoid about left over moisture/O2 - wanted to flush as much
as I could. I needed to cut in the compressor on both vehicles.
Fairly hot day too. Gas certainly flowed into the system though.

> Turn off the cylinder and start the engine with the throttle set to
> around half revs and the a/c on high fan and the doors open (to
> discourage the sytem from cycling during top up). There should be
> bubbles in the sight glass indicating the system is working and oil is
> circulating.

Yes, all OK there.

> Crack the valve ever so slightly and watch the sight glass until the
> bubbles disappear. Cease adding gas as soon as they do, or if the
> system cycles off on the thermostat.

Yes, did similar.

> The only critical part is the topping up with the engine running.
> It's a lot simpler, and safer, with gauges as it allows you to monitor
> the low side pressure to ensure that you won't create a lockup (I
> normally keep it below 600kPa during top up). Proceed slowly in the
> absence of gauges for the same end result.

As I did. I _really_ need to get gauges though. This really
is something you can do by feel and experience, however always
left with the feeling "too much". The too less is evident by the
hissing sound from the TX valve though.

> I wouldn't gas any system without evacuating it, however judging by
> some of the vacuum pumps I've seen and the time for which they're
> connected half the a/c trade may as well not bother.

I'm paranoid about what sort of acid the moisture will turn into.

The Smurf system, while working for now, _will_ need further
attention soon. Stop gap measure - he was onto me about it
due to the current weather.

> You can also buy liquid line filter/driers with ¼" male flare
> connectors from any commercial refrigeration parts supplier. I use
> one in series with the gas bottle since the stuff sold for fuel isn't
> likely to be particularly clean or dry. Cap the filter between uses,
> and they're also cheap enough to replace often.

Yep, all a matter of the right tools.

> Gauges are absolutely essential to faultfinding a system -- you might
> just get lucky if there is no fault. :)

I think I got lucky with the friend's Smurf - I'll have to see if that
turned out right - hopefully :-)

[Patrick Young]

kevcat wrote:

> I saw a video done by some people who wanted to start using propane in
> car A/C but QLD Transport said no
> too risky, they say, might catch fire in a crash

I've pumped my 'lux A/C up and down with propane. Really - the
quantity required would not fully cook your pork chop on a BBQ.

Now a L/R with a cool-a-cab on the roof - different matter.

[Fred Ferd]

> 3 of them sitting in a car(XF Falcon sedan) and sitting on the centre
> console was a burning candle
> they had the car running and had a valve inside to imitate a ruptured
> pipe
> then they opened the valve so all the gas entered the cabin
> nothing just the smell of gas
>
>
> the area inside the cabin is way to small for the amount of gas to
> ignite, too rich
>

No, too weak.

the cabin started at 0% gas. If it finished too strong, then sometime
between start and finish it must have gone through a % that was too weak.

but anyway the thing is that the ingition source may be a shorting wire or
something ...which might occur in a confined space where the leak can easily
reach explosive mix %'s.

[Clockmeister]

"kevcat" <kevcat@dodo.com.au> wrote in message
news:421879DE.C47D18E4@dodo.com.au...
>
>
>
> > You should also label the system clearly as containing R290
> > (propane). This may not even be road legal in your state.
>
> I saw a video done by some people who wanted to start using propane in
> car A/C but QLD Transport said no
> too risky, they say, might catch fire in a crash
>
> so these people contacted the guy who runs Dangerous Goods Training at
> Beenleigh, he looked at the the idea and said yes it would be safe
> so they made a video
> 3 of them sitting in a car(XF Falcon sedan) and sitting on the centre
> console was a burning candle
> they had the car running and had a valve inside to imitate a ruptured
> pipe
> then they opened the valve so all the gas entered the cabin
> .
> .
> .
> nothing
> just the smell of gas
>
>
> the area inside the cabin is way to small for the amount of gas to
> ignite, too rich
>
> QLD Transport still said no

Not surprisingly, because a candle on the dash hardly simulates an accident
scene. There are simply too many variables that could potentially lead to
ignition.

[Toby Ponsenby]

On Sun, 20 Feb 2005 14:53:07 GMT, Fred Ferd wrote:

>> 3 of them sitting in a car(XF Falcon sedan) and sitting on the centre
>> console was a burning candle
>> they had the car running and had a valve inside to imitate a ruptured
>> pipe
>> then they opened the valve so all the gas entered the cabin
>> nothing just the smell of gas
>>
>>
>> the area inside the cabin is way to small for the amount of gas to
>> ignite, too rich
>>
>
> No, too weak.
>
> the cabin started at 0% gas. If it finished too strong, then sometime
> between start and finish it must have gone through a % that was too weak.
>
> but anyway the thing is that the ingition source may be a shorting wire or
> something ...which might occur in a confined space where the leak can easily
> reach explosive mix %'s.

We've been here before.

So for clarity.
Why not ask those disgusting bastards who make/made R143a and R12 just
what the by-products of their product are?
They probably won't tell you Phosgene is one of them - in the case of
R12, and fuck knows what they'll tell you about R134a. But whatever
they tell you that'll be a lie, almost for sure.
Now we all know what the by-products of combination of LPG and
IsoButane are.
Don't we?
Either way, given the options I reckon I'll take my chances with a
minor explosion of R290a (Don't know where R290 = Propane, and R600a =
Isobutane, is that the trick?)type material any-day before believing
the same prang or whatever is *safer*, or *less_dangerous* to me with
either of the commercial designed for cars stuff.
Suure, they might be termed as non-flammable. But with cars, that
ain't the real deal. Especially with a little oil mixed, R134a will go
off rather well.
With motor vehicles it's the 'fire' element and what's there to be
burned that is the worry - not the risk of the stuff getting out of
the fridge into the supermarket wood-duck space.



Seems to me we're being scammed.
Again.
By the money end of town.
Again.

Seems to me that CO2 is the go. And exchanger systems. That why Higher
Voltage electrical systems are being planned?
And fuel cells. (Must remember to buy some platinum.)
And here's some light reading from 1995.
Not offered as any sort of proof, of course:-)

<http://yarchive.net/ac/r406a.html>


--
Toby
quidquid latine dictum
sit, altum viditur

[Justin Thyme]

"kevcat" <kevcat@dodo.com.au> wrote in message
news:421879DE.C47D18E4@dodo.com.au...
>
>
>
>> You should also label the system clearly as containing R290
>> (propane). This may not even be road legal in your state.
>
> I saw a video done by some people who wanted to start using propane in
> car A/C but QLD Transport said no
> too risky, they say, might catch fire in a crash
>
> so these people contacted the guy who runs Dangerous Goods Training at
> Beenleigh, he looked at the the idea and said yes it would be safe
> so they made a video
> 3 of them sitting in a car(XF Falcon sedan) and sitting on the centre
> console was a burning candle
> they had the car running and had a valve inside to imitate a ruptured
> pipe
> then they opened the valve so all the gas entered the cabin
If it's the same video I saw, it doesn't prove a thing about the safety of
the gas. The video I saw had the candle quite high in the car. Propane gas
is quite a bit heavier than air. The gas would have come from the AC,
settled on the floor of the car, and dissipated from there. The release of
the gas was from inside the car - the evaporator, so it was low pressure (ie
slow leak), and low temperature. All these factors combined mean that there
was no way in hell that candle was going to ignite any gas.
In an accident however, the condensor is likely to be ruptured. Yes this is
outside the passenger compartment, but it is high pressure (fast release),
high temperature, and in an area that is likely to be exposed to sparks and
high heat in the accident. In this circumstance ignition is much more likely
than the candle-in-the-car scenario. I'm not happy at all by the idea of
flammable gases floating around in the car - isn't it bad enough we have
flammable fuels, without extra gases in situations where they are even more
likely to be exposed to combustion. Give me CFC based A/C any day. Oh yeah,
they banned them cos of some crock about it destroying the ozone layer. the
real story is that du-ponts patent was running out and they wanted to make
sure other patented gases were used instead of having the CFC market open to
everyone.
> .
> .
> .
> nothing
> just the smell of gas
>
>
> the area inside the cabin is way to small for the amount of gas to
> ignite, too rich
>
> QLD Transport still said no
>
> but I bet there are plenty of cars getting about with propane in their
> A/C
> hell of a lot cheaper and is just as/more efficient as any of the other
> gases used
> just that it is quite flammable
>
> Kev

[Patrick Young]

Justin Thyme wrote:

> than the candle-in-the-car scenario. I'm not happy at all by the idea of
> flammable gases floating around in the car - isn't it bad enough we have
> flammable fuels, without extra gases in situations where they are even more
> likely to be exposed to combustion. Give me CFC based A/C any day. Oh yeah,

I'm the other way around. I really have no problem with propane in the
A/C as firstly there is not much of it. Secondly the additive stinks!

On my friend's vehicle the leak was inside the cabin, the TX valve. The
fact we had used propane gave an instant clue to the problem, then easy
to find after seeing the oil leak on the TX valve.

Petrol in a motor vehicle, OTOH I'm *not* happy with. I won't own a
petrol vehicle after the crash and burn accidents I've seen/heard of.

After owning a turbo diesel I'd _never_ want to anyway.

[John_H]

Justin Thyme wrote:

>
>In an accident however, the condensor is likely to be ruptured. Yes this is
>outside the passenger compartment, but it is high pressure (fast release),
>high temperature, and in an area that is likely to be exposed to sparks and
>high heat in the accident. In this circumstance ignition is much more likely
>than the candle-in-the-car scenario. I'm not happy at all by the idea of
>flammable gases floating around in the car - isn't it bad enough we have
>flammable fuels, without extra gases in situations where they are even more
>likely to be exposed to combustion. Give me CFC based A/C any day.

Yes indeed... a whiff of phosgene is always preferable to having your
hair singed! :)

--
John H

[dron]

John_H wrote:
> Justin Thyme wrote:
>
>
>>In an accident however, the condensor is likely to be ruptured. Yes this is
>>outside the passenger compartment, but it is high pressure (fast release),
>>high temperature, and in an area that is likely to be exposed to sparks and
>>high heat in the accident. In this circumstance ignition is much more likely
>>than the candle-in-the-car scenario. I'm not happy at all by the idea of
>>flammable gases floating around in the car - isn't it bad enough we have
>>flammable fuels, without extra gases in situations where they are even more
>>likely to be exposed to combustion. Give me CFC based A/C any day.
>
>
> Yes indeed... a whiff of phosgene is always preferable to having your
> hair singed! :)
>
> --
> John H
I Think I will stick to doing my own AC work and not follow the free
advice. I have and do use an lpg based gas on some old earthmoving
systems but 134a works well if you know how to use it and set the system
up. Barby gas is not clean and not good in the AC. You could atleast
have run it through a dryer 1st.

[John_H]

kevcat wrote:

>
>I saw a video done by some people who wanted to start using propane in
>car A/C but QLD Transport said no
>too risky, they say, might catch fire in a crash

It's almost certainly got shit all to do with what QT says.
Automotive air conditioning is regulated by the Qld Environmetal
Protection Agency.

Not that they're likely to give it the nod either, in spite of there
being no law to prohibit its use in Q. Nearest thing to it is the
regulation requiring gas fitters to be licenced -- to which the
authorities turn a blind eye for every 9kg gas cylinder that's ever
purchased.

--
John H

[John McKenzie]

John_H wrote:
>
> Yes indeed... a whiff of phosgene is always preferable to having your
> hair singed! :)

Doesn't it have to be exposed to fairly excessive temps to turn into
that though (as in rupture and spray direct on the exhaust manifold, in
an enclosed space?)??




> --
> John H

--
John McKenzie

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$LOGNAME@localhost $USER@localhost $USER@$HOST -h1024@localhost
root@mailloop.com president@whitehouse.gov vice.president@whitehouse.gov
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abuse@federalpolice.gov.au

[John_H]

John McKenzie wrote:

>John_H wrote:
>>
>> Yes indeed... a whiff of phosgene is always preferable to having your
>> hair singed! :)
>
>Doesn't it have to be exposed to fairly excessive temps to turn into
>that though (as in rupture and spray direct on the exhaust manifold, in
>an enclosed space?)??

Smokers are the ones who really need to worry -- either way! :))

Law enforcement should also take it seriously....
http://www.zarc.com/english/other_sprays/nonflam/refrigeration.html

--
John H

[kevcat]

John_H wrote:
>
> kevcat wrote:
>
> >
> >I saw a video done by some people who wanted to start using propane in
> >car A/C but QLD Transport said no
> >too risky, they say, might catch fire in a crash
>
> It's almost certainly got shit all to do with what QT says.
> Automotive air conditioning is regulated by the Qld Environmetal
> Protection Agency.


He told us it was a presentaion for QT

Kev

[Patrick Young]

Toby Ponsenby wrote:

> <http://yarchive.net/ac/r406a.html>

So true... Actually it is fun letting the gas out
of an R290 system. Bubbly oil comes out that is almost
screaming at you: OI - where did that refrigerant I was
miscible with go :-)

R134a in an R12 system is certainly a *no-go* in my book:

....

3) R-134a has a lower "critical" temp. Critical temp of a
gas is the temp which at or above it cannot be liqufied,
at any pressure. R-134a crit is 214F or so, R-12 is
around 233F. Condensor temps (due to the hot radiator
being there) can easily hit 212F or more during
"hot idle" (gridlock).. R-134a ceases to work (plus has
very high pressures over 450 PSIG) under these temps.

4) R-134a has lower capacity (in an R-12 system), than R-12 or
other substitutes. R-134a has a boiling point of -15F
vs -21F for R-12.

5) R-134a can be made to have good performance, but this
requires design changes, notably a MUCH larger condenser,
higher airflow, etc (easier to do in a NEW CAR)

[Patrick Young]

Patrick Young wrote:

> R134a in an R12 system is certainly a *no-go* in my book:

R22 might be a good match for R290/R12

Feck it - the back window of my pickup already fogs up
on the _outside_ while cooling a bottle of water in
the cup holder at the same time :-p