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#1
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AUTO AC suction pressure low
I have an '88 New Yorker that has been converted to 134.
I've vacuumed out the system and added two cans of R134, this worked fine for a while but stopped cooling after 15 minutes. System is still charged. Looking at the suction side I see a vacuum, this slowly goes away after a minute and the AC clutch kicks in and it runs back down into a vacuum. I suspect that I must have a blockage somewhere. Could a drier do that? Or is this more likely to be a condensor or something else. How do you tell? Anyone have that chart of low side and high side pressures and what the trouble may be? Jeff |
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#2
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AUTO AC suction pressure low
If you didn't add the oil conditioner oil charge, the PAG oil is congealing and causing a roaming blockage. -- jeffcoslacker ------------------------------------------------------------------------ jeffcoslacker's Profile: http://www.automotiveforums.com/vbul...?userid=219638 View this thread: http://www.automotiveforums.com/vbul...d.php?t=582883 http://www.automotiveforums.com |
#3
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AUTO AC suction pressure low
On Fri, 23 Jun 2006 22:07:21 GMT, Jeff > wrote:
> I have an '88 New Yorker that has been converted to 134. > > I've vacuumed out the system and added two cans of R134, A can is 12 ounces x 2 = 24 ounces. Capacity of this system before conversion is about 40 ounces. Subtract about 15% for change of refrigerant type and the system is still badly undercharged. You would be a hair over with a third can. There could be a bad expansion valve as well. Don www.donsautomotive.com > this worked >fine for a while but stopped cooling after 15 minutes. System is still >charged. > > Looking at the suction side I see a vacuum, this slowly goes away >after a minute and the AC clutch kicks in and it runs back down into a >vacuum. > > I suspect that I must have a blockage somewhere. Could a drier do >that? Or is this more likely to be a condensor or something else. How do >you tell? Drier should have equal temperature on the lines in and out. A restriction causes a cold area from that point on. That is what the expansion valve or tube does. > Anyone have that chart of low side and high side pressures and what >the trouble may be? Original specs don't mean much after a conversion has been done. But look for 15-25 PSI low side, 250-350 high side at 90* ambient, 1750 rpm. Don www.donsautomotive.com > Jeff |
#4
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AUTO AC suction pressure low
Don wrote:
> On Fri, 23 Jun 2006 22:07:21 GMT, Jeff > wrote: > > >> I have an '88 New Yorker that has been converted to 134. >> >> I've vacuumed out the system and added two cans of R134, > > > A can is 12 ounces x 2 = 24 ounces. Capacity of this system before > conversion is about 40 ounces. Subtract about 15% for change of > refrigerant type and the system is still badly undercharged. You > would be a hair over with a third can. > > There could be a bad expansion valve as well. New expansion valve. I had been having trouble. Seemed like high head pressure as the clutch blew on the compressor. So I put in what looked like a good used compressor and a new expansion valve. I blew out the evaporator and condensor with compressed air as I had way to much dye in it. The condensor definitely had more "resistance" to flow, but did not appear blocked. Not sure what to expect... I'll add a can in the morning and see what gives. Should only be POE and mineral oil and whatever was left of the can of dye as I added the whole can! (Had a compressor that leaked at the clutch seal). Jeff > > Don > www.donsautomotive.com > > >>this worked >>fine for a while but stopped cooling after 15 minutes. System is still >>charged. >> >> Looking at the suction side I see a vacuum, this slowly goes away >>after a minute and the AC clutch kicks in and it runs back down into a >>vacuum. >> >> I suspect that I must have a blockage somewhere. Could a drier do >>that? Or is this more likely to be a condensor or something else. How do >>you tell? > > > Drier should have equal temperature on the lines in and out. A > restriction causes a cold area from that point on. That is what the > expansion valve or tube does. > > >> Anyone have that chart of low side and high side pressures and what >>the trouble may be? > > > Original specs don't mean much after a conversion has been done. > But look for 15-25 PSI low side, 250-350 high side at 90* ambient, > 1750 rpm. > > Don > www.donsautomotive.com > > >> Jeff > > |
#5
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AUTO AC suction pressure low
jeffcoslacker wrote:
> If you didn't add the oil conditioner oil charge, the PAG oil is > congealing and causing a roaming blockage. > > What's an "oil conditioner oil charge"? I think it's mostly POE and some mineral spirits or whatever they use in R12. It's been a while since I changed it over so I suppose there could be some PAG there also. Jeff |
#6
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AUTO AC suction pressure low
Don wrote:
> On Fri, 23 Jun 2006 22:07:21 GMT, Jeff > wrote: > > >> I have an '88 New Yorker that has been converted to 134. >> >> I've vacuumed out the system and added two cans of R134, > Hi Don, > > A can is 12 ounces x 2 = 24 ounces. Capacity of this system before > conversion is about 40 ounces. Subtract about 15% for change of > refrigerant type and the system is still badly undercharged. You > would be a hair over with a third can. Third can added and it has been working all day! Thanks! Cheers, Jeff > > There could be a bad expansion valve as well. > > Don > www.donsautomotive.com > > >>this worked >>fine for a while but stopped cooling after 15 minutes. System is still >>charged. >> >> Looking at the suction side I see a vacuum, this slowly goes away >>after a minute and the AC clutch kicks in and it runs back down into a >>vacuum. >> >> I suspect that I must have a blockage somewhere. Could a drier do >>that? Or is this more likely to be a condensor or something else. How do >>you tell? > > > Drier should have equal temperature on the lines in and out. A > restriction causes a cold area from that point on. That is what the > expansion valve or tube does. > > >> Anyone have that chart of low side and high side pressures and what >>the trouble may be? > > > Original specs don't mean much after a conversion has been done. > But look for 15-25 PSI low side, 250-350 high side at 90* ambient, > 1750 rpm. > > Don > www.donsautomotive.com > > >> Jeff > > |
#7
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AUTO AC suction pressure low
bad expansion valve
Jeff wrote: > I have an '88 New Yorker that has been converted to 134. > > I've vacuumed out the system and added two cans of R134, this worked > fine for a while but stopped cooling after 15 minutes. System is still > charged. > > Looking at the suction side I see a vacuum, this slowly goes away > after a minute and the AC clutch kicks in and it runs back down into a > vacuum. > > I suspect that I must have a blockage somewhere. Could a drier do > that? Or is this more likely to be a condensor or something else. How do > you tell? > > Anyone have that chart of low side and high side pressures and what > the trouble may be? > > Jeff |
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