[DeTomaso] latest numbers in AC that has been retrofitted to 134a?

Forest Goodhart forestg at att.net
Sun Aug 7 00:11:28 EDT 2016


I would leave well enough alone..

      From: Pantdino via DeTomaso <detomaso at server.detomasolist.com>
 To: jeffcobb1 at me.com; detomaso at detomasolist.com 
 Sent: Saturday, August 6, 2016 8:23 PM
 Subject: [DeTomaso] latest numbers in AC that has been retrofitted to 134a?
   
  So at 83F ambient temp and 1500 rpm I see 7 psi on low side and 250 on
  high.
  I got one of those vent thermometers and it shows 35F at the vent.
  Sounds pretty good to me
    Or should I add a bit more 134?
  -----Original Message-----
  From: Pantdino <pantdino at aol.com>
  To: jeffcobb1 <jeffcobb1 at me.com>; detomaso <detomaso at detomasolist.com>
  Sent: Sat, Aug 6, 2016 12:23 pm
  Subject: Re: [DeTomaso] use sight glass in AC that has been retrofitted
  to 134a?
  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 <[1]jeffcobb1 at me.com>
  To: Pantdino <[2]pantdino at aol.com>; detomaso
  <[3]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
  [4]www.LiveOakConcours.org
  On Aug 4, 2016, at 11:05 PM, Pantdino <[5]pantdino at aol.com> wrote:

  Hi, Jeff,
  What should the pressures be?
  Thank you,
  Jim
  -----Original Message-----
  From: Jeff Cobb <[6]jeffcobb1 at me.com>
  To: Pantdino <[7]pantdino at aol.com>; detomaso
  <[8]detomaso at detomasolist.com>
  Cc: Jeff Cobb <[9]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
  <[10]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
  > [11]DeTomaso at server.detomasolist.com
  > [12]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. mailto:jeffcobb1 at me.com
  2. mailto:pantdino at aol.com
  3. mailto:detomaso at detomasolist.com
  4. http://www.LiveOakConcours.org/
  5. mailto:pantdino at aol.com
  6. mailto:jeffcobb1 at me.com
  7. mailto:pantdino at aol.com
  8. mailto:detomaso at detomasolist.com
  9. mailto:jeffcobb1 at me.com
  10. mailto:detomaso at server.detomasolist.com
  11. mailto:DeTomaso at server.detomasolist.com
  12. 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
DeTomaso at server.detomasolist.com
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.

  
-------------- next part --------------
   I would leave well enough alone..
     __________________________________________________________________

   From: Pantdino via DeTomaso <detomaso at server.detomasolist.com>
   To: jeffcobb1 at me.com; detomaso at detomasolist.com
   Sent: Saturday, August 6, 2016 8:23 PM
   Subject: [DeTomaso] latest numbers in AC that has been retrofitted to
   134a?
     So at 83F ambient temp and 1500 rpm I see 7 psi on low side and 250
   on
     high.
     I got one of those vent thermometers and it shows 35F at the vent.
     Sounds pretty good to me
       Or should I add a bit more 134?
     -----Original Message-----
     From: Pantdino <[1]pantdino at aol.com>
     To: jeffcobb1 <[2]jeffcobb1 at me.com>; detomaso
   <[3]detomaso at detomasolist.com>
     Sent: Sat, Aug 6, 2016 12:23 pm
     Subject: Re: [DeTomaso] use sight glass in AC that has been
   retrofitted
     to 134a?
     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 <[1][4]jeffcobb1 at me.com>
     To: Pantdino <[2][5]pantdino at aol.com>; detomaso
     <[3][6]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
     [4]www.LiveOakConcours.org
     On Aug 4, 2016, at 11:05 PM, Pantdino <[5][7]pantdino at aol.com> wrote:
     Hi, Jeff,
     What should the pressures be?
     Thank you,
     Jim
     -----Original Message-----
     From: Jeff Cobb <[6][8]jeffcobb1 at me.com>
     To: Pantdino <[7][9]pantdino at aol.com>; detomaso
     <[8][10]detomaso at detomasolist.com>
     Cc: Jeff Cobb <[9][11]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
     <[10][12]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
     > [11][13]DeTomaso at server.detomasolist.com
     > [12][14]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. mailto:[15]jeffcobb1 at me.com
     2. mailto:[16]pantdino at aol.com
     3. mailto:[17]detomaso at detomasolist.com
     4. [18]http://www.LiveOakConcours.org/
     5. mailto:[19]pantdino at aol.com
     6. mailto:[20]jeffcobb1 at me.com
     7. mailto:[21]pantdino at aol.com
     8. mailto:[22]detomaso at detomasolist.com
     9. mailto:[23]jeffcobb1 at me.com
     10. mailto:[24]detomaso at server.detomasolist.com
     11. mailto:[25]DeTomaso at server.detomasolist.com
     12. [26]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
   [27]DeTomaso at server.detomasolist.com
   [28]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. mailto:pantdino at aol.com
   2. mailto:jeffcobb1 at me.com
   3. mailto:detomaso at detomasolist.com
   4. mailto:jeffcobb1 at me.com
   5. mailto:pantdino at aol.com
   6. mailto:detomaso at detomasolist.com
   7. mailto:pantdino at aol.com
   8. mailto:jeffcobb1 at me.com
   9. mailto:pantdino at aol.com
  10. mailto:detomaso at detomasolist.com
  11. mailto:jeffcobb1 at me.com
  12. mailto:detomaso at server.detomasolist.com
  13. mailto:DeTomaso at server.detomasolist.com
  14. http://server.detomasolist.com/mailman/listinfo/detomaso
  15. mailto:jeffcobb1 at me.com
  16. mailto:pantdino at aol.com
  17. mailto:detomaso at detomasolist.com
  18. http://www.liveoakconcours.org/
  19. mailto:pantdino at aol.com
  20. mailto:jeffcobb1 at me.com
  21. mailto:pantdino at aol.com
  22. mailto:detomaso at detomasolist.com
  23. mailto:jeffcobb1 at me.com
  24. mailto:detomaso at server.detomasolist.com
  25. mailto:DeTomaso at server.detomasolist.com
  26. http://server.detomasolist.com/mailman/listinfo/detomaso
  27. mailto:DeTomaso at server.detomasolist.com
  28. http://server.detomasolist.com/mailman/listinfo/detomaso


More information about the DeTomaso mailing list