Charging A/C System

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  #1  
Old 05-29-08, 07:09 PM
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Exclamation Charging A/C System

I am about to charge my system in my 93 accord. I drained oil, flushed, etc.. I am pulling a vacuum now and letting it sit for a day or so. Do I charge on a vacuum or should I release the vacuum prior to charging?
 
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  #2  
Old 05-30-08, 04:18 AM
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At the risk of sounding harsh and p'ing you off; if you have to ask that question you probably shouldn't be doing the work.
 
  #3  
Old 05-30-08, 06:52 AM
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are you retrofitting the vehicle?
you do not release the vacum that will allow air in the system wich is one of the reasons you pull a vacum on it to begin with that and to remove moisture.
would also suggest you might think about taking it to a shop to have it filled with the proper amount of refrigerant and oil, freon capacity will vary depending on whether you are retrofitting are not.
 
  #4  
Old 05-30-08, 05:33 PM
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I understand that is the case if I am charging with R12 or R134a. I am using an alternative refrigerant and they recommend not charging on a vacuum because it is not harmed by air or moisture. Just made me start thinking.
 
  #5  
Old 05-30-08, 06:39 PM
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How would u charge it while still on a vacume? the vacume holding will tell u if u have a leak....period....if it doesnt hold a vacume....walla.....but if it does....u can charge it.....put in the recommended refrigerant, and recommended amount and pressures and walla again....if ur system isint fudged up....cold air.....
 
  #6  
Old 05-30-08, 06:49 PM
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I dont know what type of refrigerant you are using and dont know of any that would recomend charging without pulling a vacum first, while it may not actually hurt the freon any, it can cartainly damage certain components of your a/c system and when your compressor or other component fails in the near future you may want to rethink wich alternative refrigerants you use.
 
  #7  
Old 05-30-08, 07:32 PM
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I rechange ac systems in cars every day......if they have refrigerant in the system.....at all they will hold a vacume...and most likely dont have moisture or a leak.....just fill them to recommended pressures.... or generally 30 lbs pressure on the low side.....and u should have cold air.......if theres a leak.....theres no start out pressure, and they wont hold any pressure ever for very long. U need a manifold pressure gauge and only connect to the low side and charge from that side too....never from the high side.....bad stuff can happen.....
 
  #8  
Old 05-30-08, 10:53 PM
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ok, so i just charged with ester and r134a after pulling vacuum. low side is a little above 30 and high side is a little below 230. will the system always equalize when not in use? if not what does this indicate?
 
  #9  
Old 05-31-08, 12:25 AM
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yes it will equalize when not in use it may take a little while for the pressures to equalize but it is normal.
the pressures you read on low or high side will vary with ambient temperature and isnt a real good indication of freon level if it was original equiped with r 12 the general rule would be to fill with r134a to 75-80 percent of the r-12 capacity thats 12 oz of r134 for every pound of r12, if you have a temp guage you can stick in the a/c vent it will also help determine if you have enough in the system you can usually achieve a 25 - 30 degree drop in temperature from ambient at the vent with a/c on max, blower on high, car idling, so if its 80 degrees would susect temp at the vent to be around 50-55 degrees.
 
  #10  
Old 05-31-08, 11:22 AM
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First of all, thanks for everyone's help. Just to want to make sure about a couple of details. Static pressure means the equalized pressure when the car is not running? At 90 degrees fahrenheit with R134a my static pressure should be roughly 104 psig? While the car is running my low side pressure should be 30-35, what should my high side be assuming 90 degrees ambient temp?
 
  #11  
Old 05-31-08, 11:51 AM
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the most accurate way is to do it by weight, there is usually a sticker under the hood with freon capacity if its for r12 only put 3/4 of that amount in for a starting point.
on a 90 degree day would expect the low side to be 40-45psi and high side to be 250-275 but these pressures will vary a little based on not only ambient temp but the temp of your condenser and evaporator wich will not be ambient.
would expect the temp at the a/c vent to be around 60-65 degrees if its 90 outside at idle it will get colder than that while driving though as its more efficient at higher rpm.
 
  #12  
Old 05-31-08, 05:16 PM
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What if my system does not fully equalize on both sides? What does this indicate?
 
  #13  
Old 05-31-08, 08:48 PM
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What if my system does not fully equalize on both sides? What does this indicate?
Explain "FULLY"..........

20-30 pound difference , ....I personally wouldnt worry about. There are plenty of places, and plenty of situations that can "TRAP" refrigerant and prevent "PERFECT" equalization. "Static pressure is measured with the A/C OFF, and really means nothing, provided the "Operating Pressures " are within range.....

DONT OVERTHINK THIS......Getting to technical and looking for TEXTBOOK results are asking for trouble. Those pressure/Temp charts were Written for BRAND NEW vehicles, with the recommended Type of refrigerant.

You are working on a 15 year old vehicle, using something that was Just being invented when your car was Born.

Ive mentioned it in other posts, and I do have a bit of compassion , considering the expense, But there is a "FEEL" for this kind of work, and as such, I personally dont feel that A/C work is within the scope Of "DIY". Done improperly, It can be extremely hazardous, and without your Eyesight, do you really care how cold it is in the car?

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  #14  
Old 05-31-08, 09:44 PM
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Thanks, I understand what you are saying. With an ambient temp between 95-100 my vent temp is between 45-50. I am pretty happy with this and would like to thank all of you for your help through my journey.
 
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