AC Compressor replacement 2000 Bravada

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  #1  
Old 06-24-12, 07:35 PM
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AC Compressor replacement 2000 Bravada

I replaces the compressor and receiver on the my 2000 bravada. I vacuumed the system with a electric vacuum pump and held it at 25 in hg to assure all connections were tight and get all the air out.

My issue has come in recharging, this something I have done several times in the past successfully prior to the compressor change. What I am seeing now is the compressor cycling on for about 4-5 seconds every 10-12 seconds. The pressure on the low side decreases while the compressor is on, and increases during the off cycle.

I have bled some off and added more 134a to try different things but have been unable to get the compressor to stay on or get the air coming out of the vent to be less then 70 degrees, it was about 85 outside.

Prior to replacing the compressor I was able to get 50 degree air out of the system on a 90 + degree day.

Looking for what I may have missed while putting the system back together.

Thanks,
 
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  #2  
Old 06-25-12, 09:05 AM
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How much 134a did you put in the system and did you add oil to system and if so how much.
 
  #3  
Old 06-25-12, 09:10 AM
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01-99 All Eng. R-134a 31.00 oz. PAG-150 8.50 oz.
that's the specs for the Bavada AC system
 
  #4  
Old 06-25-12, 09:27 AM
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the compressor was pre oiled. the first can of 134 added had addional lube in it for the compressor. Then about 2 1/2 12 0z cans of 134A.
 
  #5  
Old 06-25-12, 11:22 AM
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Possibly the system is overcharged what were the low and high side pressures on the system with it running.
Jim
 
  #6  
Old 06-25-12, 11:26 AM
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In rereading your statement it could possibly be an orfice tube is stopped up why did you change the compressor did the old one lockup are just make a lot of noise.
 
  #7  
Old 06-25-12, 11:29 AM
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Also what is the static pressure on the system with it off.
Jim
 
  #8  
Old 06-25-12, 12:47 PM
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I changed the compressor because it was leaking around the front seal and the clutch went bad and was rubbing metal on metal.

the low side pressure while not running is in excess of 90psi. When running the pressure would drop to about 50-60 then cycle off and pressure would climb to over 90.

I do not have the guages to attached to the high side.
 
  #9  
Old 06-25-12, 06:39 PM
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You have the system overcharged your low pressure with it running should be between 30 to 40 Psi it is cycling because the high pressure side is tripping the HP switch. Bleed the system down till the low side pressure is around 30 lbs and then you can slowly add a small amount while monitoring the temp at the center outlet with the A/C on max. I would also take a good fan and set it in front of the vechile and get more air flow through the condenser coils are run some water over the coils to keep the condenser cooler and the high pressure down. Yoou should see air exiting the center outlet at approximately 45 degrees.
Jim
 
  #10  
Old 06-26-12, 07:19 AM
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Thanks Jim.

I will give this a try this evening. It sounds logical to me.

have a great day.
 
  #11  
Old 06-26-12, 01:09 PM
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One additional question about the compressor itself. I was told it is a cycling compressor that is not intended to come on and stay on. Is this the case?
 
  #12  
Old 06-27-12, 08:44 PM
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Yes the compressor will cycle but it will be dependent on the temp sensors on the a/c system. If you put the a/c in the max position it will only cycle under hard accel. as in a passing condition so that it has enough power to pass.
 
  #13  
Old 06-28-12, 08:25 AM
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bleading it down did help and it is now kicking out colder air. the pressure is no at 30-35 range while it is running. At 100 degrees outside I am getting about 68 degree air out of the system at best. This morning at about 90 degrees the temp coming out is in the 60s. I know in the past under these conditions I was able to get around 50 degree air out of the system. It there a better brand or type of 134a to use to add a bit more to improve the performance?

Thanks for all your help.
 
  #14  
Old 07-02-12, 12:33 AM
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You really need to get a set of gauges so you can see what the high pressure is some parts houses have gauges that they will loan. It sounds like you may have an orifice tube that is failing and you are not getting enough pressure drop to cause the refrigerant to draw enough heat from the inside. If you spiked a high enough pressure you could have caused damage to the orifice because if everything was operating properly you should be seeing temps around 45 in the center outlet with the system on max.
Jim
 
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