[DeTomaso] A/C Question

[Art Stephens]

Chris,
     I did replace the expansion valve just over a year ago.  I've got bulkhead fittings at the firewall which have been capped most of that time.  The bulkhead fittings are attached to the hoses going to the evaporator and expansion valve.  The expansion valve could have been open to the atmosphere for a month or two.  If it turns out to be the expansion valve,  you got your donuts :-)
Thanks,
Art

  ----- Original Message ----- 
  From: Chris Difani 
  To: Art Stephens 
  Sent: Sunday, September 03, 2006 11:30 PM
  Subject: Re: [DeTomaso] A/C Question


  Art:

  You did good. Everything that I woulda, coulda, thoughta done. On the vacuum thing, it's so dependant on temp, barometric pressure, and all of that stuff, that 28" is great.

  Now the only other thing I can possibly think of is the expansion valve. If you replaced it, it's about $15 or so, then I have absolutely no idea. But if you didn't, then I'd bet you a bag of donuts to a buck, that's the root cause of this evil. The OEM expansion valve can loose the O ring inside it, and can also catch any crud in the system since it's the "choke point" for the entire refrigeration system. Literally. It's under the dash, passenger side footwell. Snugged up against the evaporator under the dash. Usually wrapped in black spongy gunk stuff insulation (notice the very professional exact descriptive words I'm using here). 

  If your still using the original expansion valve, ESPECIALLY if it's the same one that's been in the system when it was open for all those years, then that's your problem. Heck, I'll bet two bucks to a bag of donuts.

  Chris


  ----- Original Message ----- 
  From: Art Stephens 
  To: Chris Difani 
  Cc: detomaso at realbig.com 
  Sent: Sunday, September 03, 2006 11:03 PM
  Subject: Re: [DeTomaso] A/C Question


  Chris,
       I vacuumed the system for more than an hour at 27-28",  I couldn't get to 29".  I put in 8.5 ounces of PAG oil from a can with some refrigerant.  I have a Sankyo rotary compressor.  I used a new dryer and a new expansion valve.  Most of the system has been sitting open for better than five years.  
  Thank you,
  Art

    ----- Original Message ----- 
    From: Chris Difani 
    To: Art Stephens 
    Sent: Sunday, September 03, 2006 7:26 PM
    Subject: Re: [DeTomaso] A/C Question


    Art:

    How long did you evacuate the system for? 45 minutes after the gauge hit "28" or so? Or an hour? It sounds (diagnosing over email is even worse than over a phone) that the system has air in it. Or some kind of contaminate. Did you put the right amount of oil in the compressor? 10 ounces or 12 ounces depending on the compressor. 

    But that sure sounds like a LOT of refrigerant for that system. Especially with that kind of gauge readings. 

    A lot of the AC guys do the evacuation for an hour, then they add the specified amount of refrigerant as per the factory spec's. Then add another half can or so, depending on what the thermometer is reading with the AC on, and fan on high. 134a is kind of notorious for not creating as much "cold" as 12 does in a system that was originally designed for 12. But if you've replaced the original York compressor with one of the rotary varieties, then you should be close to a 12 system, in terms of output "cool" and air flow. 

    But in any case, the key is the system evacuation, the replacement of the dryer (if it's been exposed to open atmosphere, or been in use for a few years), and then the installation of the factory recommended amount of refrigerant.

    Not that I'm an expert, but that's what I've found in my studies, and the few systems that I've successfully recharged. The evacuation is ususally best done with one of the Robinair vacuum pumps that they make for the AC trade. The converted refrigerator compressors can work... but I've never seen them get the system "down" as far as a good commercial pump will.

    Chris

    Chris Difani
    '73 L #5829 "LITNNG"
    Sacramento, CA
    Email: cdifani at pacbell dot net
    Chris





    ----- Original Message ----- 
    From: "Art Stephens" <artstephens at charter.net>
    To: <detomaso at realbig.com>
    Sent: Sunday, September 03, 2006 6:05 PM
    Subject: [DeTomaso] A/C Question


    >     I have already added 75 ounces of 134 refrigerant to my newly converted system.  The gauges don't climb above 20 psi on the low side and 210 psi on the high side,  in 90 degree weather.  What gives?  My instructions say I should see higher numbers.  Do I just keep adding more?  At ten bucks a can,  I figured I better start asking some questions.  The air blows cold,  but I could stand colder.
    > Art
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