A/C recharge question...

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  #1  
Old 06-14-05, 01:57 PM
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A/C recharge question...

91 Mustang 2.3L with factory air.

Had a leak in the high pressure line and lost all refrigerant. I removed the line and covered the openings with rags. Because I had already lost all refrigerant I replaced all the orings I knew about... compressor, high pressure line, liquid line, accumulator, etc. I had the line repaired the next day and put everything back tight. Total time system open was 1 day. I only added one can of 134a and it brought my readings to 40Low and 170High. The line is sweating back and cold but system not cooling very well. I bought an orifice tube but found mine was permantly fixed in the line so couldn't change it last night.

My question... Do I need to pull a vacuum on the system or can I just add the 134a like I did?
 

Last edited by scrollmaster; 06-14-05 at 02:07 PM.
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  #2  
Old 06-14-05, 02:14 PM
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you should pull a vacum on the system anytime the system is empty, before refilling with freon.
the system may function without pulling a vacum but its performance will not be as good than if you had vacumed down the system prior to filling, and you will have excessive high side pressures wich could lead to future problems.
 
  #3  
Old 06-14-05, 02:29 PM
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Should have put vacc on it. Did you say you only put one can back in it? Doesn't sound like nearly enough. What does the recharge sticker say for lbs required? Add that much back to it with oil if you vac the system.
 
  #4  
Old 06-14-05, 03:12 PM
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this vehicle should of originally been equiped with r12 if you are retrofitting it to r134a you should only fill to 75 percent of the r12 capacity if it was retrofitted by a shop it should have a new sticker under the hood with amount of freon and oil installed at the time it was retrofitted.
 
  #5  
Old 06-16-05, 03:27 PM
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The only sticker for the a/c is the original r-12 which calls for 2.2lbs. I don't know when converted to 134a because was already done when I purchased vehicle.

Does vac on the a/c system remove the oil? I didn't think so and did not add any oil back to the system because didn't think I would loose any during the process.

Here's what I've done. I picked up a vac from autozone on the loaner program. I also found a new liquid line at O'Reilly Auto and replaced that so would have new orifice tube. Vacuum pulled to -28.5 and I ran for 20 minutes as per pump instructions. I then shut off pump and let set for another 20 minutes and still read -28.5 so satisfied it was not leaking I added a total of 2 - 12oz cans of 134a. Cooling much better but not doing as expecting, especially in town driving. After 24 oz of 134a the readings are as follows...
Outside temp at about 88-90degrees...
At idle (approx 700 rpm) = 50+ low and 225+ high
At approx 2000 rpm = 35 low and 260+ high

I'm kinda green at this and not sure if this is too high or low but I want to learn.
 
  #6  
Old 06-16-05, 05:02 PM
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Those pressure readings are actually pretty good. At 24 oz., you're still a little undercharged. 80% of the R12 spec. would be right at 28oz. You probably did lose some oil, at least through the leak. Problem is, it's impossible to know how much. If possible, I'd try to get around 2oz. of oil into it - make sure it's R134 compatible (ester oil). One thing to keep in mind as well - 134 will never cool as well as an R12 system, especially a retro-fit system. Stick a thermometer in the outlet, if it's 45-50 on a 90 day, it's about as good as it will get.
 
  #7  
Old 06-17-05, 06:18 AM
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I will take the mustang to work with me today and pickup up some ester oil and put that in between my work and see how that does. I checked the condenser coil when I got in last nite and was also in need of cleaning but was too late and too tired then. Is there something better than just water to clean it with?
 
  #8  
Old 06-17-05, 07:20 AM
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If you're talking about crud across the front of the condensor - garden hose should work just fine. Doubt that was causing you any troubles though; restricted airflow across the condensor will shoot the high side pressure way up.
 
  #9  
Old 06-17-05, 01:56 PM
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Okay, I picked up a 2oz can of ester oil and put that in this morning and also added about 1/2 can of 134a and it did get cooler but has been very overcast and cool today as compared to the humid scorchers the last few days so will have to wait and see what happens then but should be a noticeable improvement.

You guys are sure appreciated...
Dennis
 
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