[DeTomaso] use sight glass in AC that has been retrofitted to 134a?
Don Thomas
don.thomas.ieee at gmail.com
Sat Aug 6 21:02:42 EDT 2016
Jim,
Did you change the seals and hoses for R134a ?
R134 reacts with certain components of "rubber" or "neoprene" seals that
are quite happy in r12 systems and causes them to deteriorate.
(ref: http://www.acsource.net/acforum/viewtopic.php?f=1&t=8578 )
And the pressure differential sounds like you may have a screen clogged...
(Ref:
http://server.detomasolist.com/pipermail/detomaso/2008-April/031257.html )
Also, check what oil you are using in the AC system... the recommended oil
is PAG-DEC.
(Ref: http://www.autoactech.com/issues.htm )
I hope that helps.
Best regards,
-dt
On Sat, Aug 6, 2016 at 12:23 PM, Pantdino via DeTomaso <
detomaso at server.detomasolist.com> wrote:
> Jeff,
>
> I hooked up the high pressure side gauge and get these numbers:
>
> before starting car, 100 psi both sides
>
> after system settles down, at 1500 rpm, low side 7 psi, high side 225
> psi. As the car warmed the engine speed increased to maybe 1750 rpm
> and the high side was creeping up to 240-250 but the low was staying at
> 5-7.
>
> Ambient temp was 77F, so should be about 40-45 low side, 170 high side.
>
> According to the info sheet, this "Hi side too high, low side too low"
> situation would imply "blockage of expansion valve or orifice tube."
> Would that be from having the R12 valve in a system now using 134?
>
> I used my laser thermometer on the vents and got 20-40F, but I suspect
> that kind of thermometer is not accurate for this application because
> on my street car I got like 13F, which I think cannot be right.
>
> Anyway, it seems to me if I add more 134 I run the risk of blowing the
> high side hose at 3000 rpm and 85F temp. Does that sound right?
>
> I do have 15 12 oz cans of old school R12 I bought way back when, so I
> could switch to R12, but I would have to take the car to have the 134
> recycled, replace the dryer, put the system under vacuum, etc so would
> like not to.
>
> Thank you,
>
> Jim
> -----Original Message-----
> From: JEFFREY COBB <jeffcobb1 at me.com>
> To: Pantdino <pantdino at aol.com>; detomaso <detomaso at detomasolist.com>
> Sent: Fri, Aug 5, 2016 3:37 am
> Subject: Re: [DeTomaso] use sight glass in AC that has been retrofitted
> to 134a?
> Jim,
> All cars use different pressures and for examples this week we did a/c
> work on a 124 Fiat, many Benz-Bmws-Toyotas, a 71 e-type, Ford +Chevy
> trucks, a Cobra kit car and a Mangusta.
> But basic pressures at 1,500 rpm with cooling fans on and on high, with
> both windows open, rear and front hatch closed, high fan and not on
> recirc should be about 35 + - low side and 250 + - high. Seems like a
> 7:1 ratio works the best. Converted systems do need different numbers
> but never too much of a change. So your low range should vary from 20
> to 38 psi and the high 210 to 260 psi as long as above written
> parameters are meet. The proper pressures will equate to the coolest
> temps. You have to note that and remember you are just setting the vent
> output for the coolest temp not some pre-considered ideal temp you hope
> for.
> About 30 % of all of our a/c fixes are fixing the stuck on heaters. We
> are in hot Louisiana, make sure your heater is truly shut off by doing
> a liquid test.
> Do use the correct oil and add 2 oz if you are not sure of how much is
> in. You can always expel the working high side into a cloth or jug for
> 2 seconds to get an idea if you are oily enough. A lot of spit
> indicates fine but dry expelled gas needs oil.
> Keep cool,
> Jeff
> Jeff Cobb- I pad
> W-225-343-7525
> C-225-907-4514
> Jeff Cobb Auto Works
> 1316 S. Acadian Thruway
> Baton Rouge, La.
> 70806
> [1]www.LiveOakConcours.org
> On Aug 4, 2016, at 11:05 PM, Pantdino <[2]pantdino at aol.com> wrote:
>
> Hi, Jeff,
> What should the pressures be?
> Thank you,
> Jim
> -----Original Message-----
> From: Jeff Cobb <[3]jeffcobb1 at me.com>
> To: Pantdino <[4]pantdino at aol.com>; detomaso
> <[5]detomaso at detomasolist.com>
> Cc: Jeff Cobb <[6]jeffcobb1 at me.com>
> Sent: Thu, Aug 4, 2016 6:55 pm
> Subject: Re: [DeTomaso] use sight glass in AC that has been retrofitted
> to 134a?
> The sight glass is always used as a reference point. You must go by the
> dual gauges.
> Never by the low side only.
> Jeff Cobb
> On Aug 4, 2016, at 8:44 PM, Pantdino via DeTomaso
> <[7]detomaso at server.detomasolist.com> wrote:
> > After switching the AC system to 134a, do you use the sight glass in
> > the dryer or go by the pressure at the low pressure port like with
> > modern cars?
> >
> > Sorry, but I don't recall what I learned several years ago when I
> > switched the system over.
> >
> > Jim Oddie
> > _______________________________________________
> >
> >
> > Detomaso Email List is not managed by POCA
> > Posted emails must not exceed 1.5 Megabytes
> > DeTomaso mailing list
> > [8]DeTomaso at server.detomasolist.com
> > [9]http://server.detomasolist.com/mailman/listinfo/detomaso
> >
> > To manage your subscription (change email address, unsubscribe, etc.)
> use the links above.
> >
> > Members who post to this list grant license to the list to forward
> any message posted here to all past, current, or future members of the
> list. They also grant the list owner permission to maintain an archive
> or approve the archiving of list messages.
>
> References
>
> 1. http://www.LiveOakConcours.org/
> 2. mailto:pantdino at aol.com
> 3. mailto:jeffcobb1 at me.com
> 4. mailto:pantdino at aol.com
> 5. mailto:detomaso at detomasolist.com
> 6. mailto:jeffcobb1 at me.com
> 7. mailto:detomaso at server.detomasolist.com
> 8. mailto:DeTomaso at server.detomasolist.com
> 9. http://server.detomasolist.com/mailman/listinfo/detomaso
>
> _______________________________________________
>
>
> Detomaso Email List is not managed by POCA
> Posted emails must not exceed 1.5 Megabytes
> DeTomaso mailing list
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>
> To manage your subscription (change email address, unsubscribe, etc.) use
> the links above.
>
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> message posted here to all past, current, or future members of the list.
> They also grant the list owner permission to maintain an archive or approve
> the archiving of list messages.
>
-------------- next part --------------
Jim,
Did you change the seals and hoses for R134a ?
R134 reacts with certain components of "rubber" or "neoprene" seals
that are quite happy in r12 systems and causes them to deteriorate.
(ref: [1]http://www.acsource.net/acforum/viewtopic.php?f=1&t=8578 )
And the pressure differentialA sounds like you may have a screen
clogged...
(Ref:
[2]http://server.detomasolist.com/pipermail/detomaso/2008-April/031257.
html )
Also, check what oil you are using in the AC system... the recommended
oil is PAG-DEC.
(Ref: [3]http://www.autoactech.com/issues.htm )
I hope that helps.
Best regards,
-dt
On Sat, Aug 6, 2016 at 12:23 PM, Pantdino via DeTomaso
<[4]detomaso at server.detomasolist.com> wrote:
A A Jeff,
A A I hooked up the high pressure side gauge and get these numbers:
A A before starting car, 100 psi both sides
A A after system settles down, at 1500 rpm, low side 7 psi, high
side 225
A A psi.A As the car warmed the engine speed increased to maybe
1750 rpm
A A and the high side was creeping up to 240-250 but the low was
staying at
A A 5-7.
A A Ambient temp was 77F, so should be about 40-45 low side, 170
high side.
A A According to the info sheet, this "Hi side too high, low side
too low"
A A situation would imply "blockage of expansion valve or orifice
tube."
A A Would that be from having the R12 valve in a system now using
134?
A A I used my laser thermometer on the vents and got 20-40F, but I
suspect
A A that kind of thermometer is not accurate for this application
because
A A on my street car I got like 13F, which I think cannot be right.
A A Anyway, it seems to me if I add more 134 I run the risk of
blowing the
A A high side hose at 3000 rpm and 85F temp.A Does that sound
right?
A A I do have 15 12 oz cans of old school R12 I bought way back
when, so I
A A could switch to R12, but I would have to take the car to have
the 134
A A recycled, replace the dryer, put the system under vacuum, etc
so would
A A like not to.
A A Thank you,
A A Jim
A A -----Original Message-----
A A From: JEFFREY COBB <[5]jeffcobb1 at me.com>
A A To: Pantdino <[6]pantdino at aol.com>; detomaso
<[7]detomaso at detomasolist.com>
A A Sent: Fri, Aug 5, 2016 3:37 am
A A Subject: Re: [DeTomaso] use sight glass in AC that has been
retrofitted
A A to 134a?
A A Jim,
A A All cars use differentA pressures and for examples this week we
did a/c
A A work on a 124 Fiat, many Benz-Bmws-Toyotas, a 71 e-type, Ford
+Chevy
A A trucks, a Cobra kit car and a Mangusta.
A A But basic pressures at 1,500 rpm with cooling fans on and on high,
with
A A both windows open, rear and front hatch closed, high fan and not
on
A A recirc should be about 35 + - low side and 250 + - high. Seems
like a
A A 7:1 ratio works the best. Converted systems do need different
numbers
A A but never too much of a change. So your low range should vary from
20
A A to 38 psi and the high 210 to 260 psi as long as above written
A A parameters are meet. The proper pressures will equate to the
coolest
A A temps. You have to note that and remember you are just setting the
vent
A A output for the coolest temp not some pre-considered ideal temp you
hope
A A for.
A A About 30 % of all of our a/c fixes are fixing the stuck on
heaters. We
A A are in hot Louisiana, make sure your heater is truly shut off by
doing
A A a liquid test.
A A Do use the correct oil and add 2 oz if you are not sure of how
much is
A A in. You can always expel the working high side into a cloth or jug
for
A A 2 seconds to get an idea if you are oily enough. A lot of spit
A A indicates fine but dry expelled gas needs oil.
A A Keep cool,
A A Jeff
A A Jeff Cobb- I pad
A A W-225-343-7525
A A C-225-907-4514
A A Jeff Cobb Auto Works
A A 1316 S. Acadian Thruway
A A Baton Rouge, La.
A A 70806
A A [1][8]www.LiveOakConcours.org
A A On Aug 4, 2016, at 11:05 PM, Pantdino <[2][9]pantdino at aol.com>
wrote:
A A Hi, Jeff,
A A What should the pressures be?
A A Thank you,
A A Jim
A A -----Original Message-----
A A From: Jeff Cobb <[3][10]jeffcobb1 at me.com>
A A To: Pantdino <[4][11]pantdino at aol.com>; detomaso
A A <[5][12]detomaso at detomasolist.com>
A A Cc: Jeff Cobb <[6][13]jeffcobb1 at me.com>
A A Sent: Thu, Aug 4, 2016 6:55 pm
A A Subject: Re: [DeTomaso] use sight glass in AC that has been
retrofitted
A A to 134a?
A A The sight glass is always used as a reference point. You must go
by the
A A dual gauges.
A A Never by the low side only.
A A Jeff Cobb
A A On Aug 4, 2016, at 8:44 PM, Pantdino via DeTomaso
A A <[7][14]detomaso at server.detomasolist.com> wrote:
A A > After switching the AC system to 134a, do you use the sight
glass in
A A > the dryer or go by the pressure at the low pressure port like
with
A A > modern cars?
A A >
A A > Sorry, but I don't recall what I learned several years ago when
I
A A > switched the system over.
A A >
A A > Jim Oddie
A A > _______________________________________________
A A >
A A >
A A > Detomaso Email List is not managed by POCA
A A > Posted emails must not exceed 1.5 Megabytes
A A > DeTomaso mailing list
A A > [8][15]DeTomaso at server.detomasolist.com
A A > [9][16]http://server.detomasolist.com/mailman/listinfo/detomaso
A A >
A A > To manage your subscription (change email address, unsubscribe,
etc.)
A A use the links above.
A A >
A A > Members who post to this list grant license to the list to
forward
A A any message posted here to all past, current, or future members of
the
A A list. They also grant the list owner permission to maintain an
archive
A A or approve the archiving of list messages.
References
A A 1. [17]http://www.LiveOakConcours.org/
A A 2. mailto:[18]pantdino at aol.com
A A 3. mailto:[19]jeffcobb1 at me.com
A A 4. mailto:[20]pantdino at aol.com
A A 5. mailto:[21]detomaso at detomasolist.com
A A 6. mailto:[22]jeffcobb1 at me.com
A A 7. mailto:[23]detomaso at server.detomasolist.com
A A 8. mailto:[24]DeTomaso at server.detomasolist.com
A A 9. [25]http://server.detomasolist.com/mailman/listinfo/detomaso
_______________________________________________
Detomaso Email List is not managed by POCA
Posted emails must not exceed 1.5 Megabytes
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To manage your subscription (change email address, unsubscribe,
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Members who post to this list grant license to the list to forward
any message posted here to all past, current, or future members of
the list. They also grant the list owner permission to maintain an
archive or approve the archiving of list messages.
References
1. http://www.acsource.net/acforum/viewtopic.php?f=1&t=8578
2. http://server.detomasolist.com/pipermail/detomaso/2008-April/031257.html
3. http://www.autoactech.com/issues.htm
4. mailto:detomaso at server.detomasolist.com
5. mailto:jeffcobb1 at me.com
6. mailto:pantdino at aol.com
7. mailto:detomaso at detomasolist.com
8. http://www.LiveOakConcours.org/
9. mailto:pantdino at aol.com
10. mailto:jeffcobb1 at me.com
11. mailto:pantdino at aol.com
12. mailto:detomaso at detomasolist.com
13. mailto:jeffcobb1 at me.com
14. mailto:detomaso at server.detomasolist.com
15. mailto:DeTomaso at server.detomasolist.com
16. http://server.detomasolist.com/mailman/listinfo/detomaso
17. http://www.LiveOakConcours.org/
18. mailto:pantdino at aol.com
19. mailto:jeffcobb1 at me.com
20. mailto:pantdino at aol.com
21. mailto:detomaso at detomasolist.com
22. mailto:jeffcobb1 at me.com
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