Ac Compressor Question.

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Old 06-25-19, 04:06 PM
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Ac Compressor Question.

I have a 2011 GMC Acadia in which I replaced the discharge line due to a large hole. After replacing the line I vacuumed the lines. I then filled up with R134A and the air did not get cold. The gauges held vacuum after placing the vacuum for two hours so I don't believe there's another leak. I tested the clutch by hooking it up to a 12v source and I heard it engage but when the ac is on I don't hear it engaging or I hear a very faint engagement, Not the pronounced click it would make when functioning properly. How can you check if the compressor is not compressing the freon? Is there anything else it could be? Thanks.
 
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Old 06-26-19, 01:54 AM
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so how much Freon did you put in?
if the front of the compressor is turning then the compressor is engaged if its not compressing it usually can be seen by gauge pressure readings high side will be reading low and low side will be higher than normal.
 
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Old 06-26-19, 07:43 AM
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Thanks for the reply. I put in one 12oz can of r134 a. I put it in with the gauge that came with the can because I didn't have the adapter to put it in with the ac gauges. The can gauge was reading 55 on a 90 degree day. That was almost red lining on the gauge. I know there is a way to tell if the compressor is bad by using the high/low side gauges but I don't know how to do it. I've tried looking it up but the videos mainly are about the clutch. Can you tell me how to do it and what the readings on the high and low side should be? I know both sides should be about even before starting the car and then there should be a change in the gauges when the car and ac are on. Is that correct? I just don't know what those readings should be to see if the compressor is shot. Thanks again for any help.
 
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Old 06-26-19, 01:49 PM
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would suspect the compressor clutch is not coming on would look and see if the front clutch plate is turning with the a/c on.
compressors can fail in 2 ways the most common is they lock up the less common is they cannot build much pressure and they also lose suction so they cannot pull the low side down to normal levels so often they wont be a large difference between low and high pressures I cant really give you pressures cause there is varying degrees of this type of failure, all I can tell you is your low side is to high could be cause the compressor clutch is not coming on at all or another issue.
 
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Old 06-26-19, 02:27 PM
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Did you pre fill compressor with AC oil before installing it? As if you did not, you have air bubble in their PLUS you will ruin your compressor. Seize it.
Did you put in only freon or freon+oil mix?
You can't trust those cheap gauges on the refill cans. Unfortunately, they are "for your education only".
I'd have shortened the pressure switch terminals and see what happens. If system comes up, problem is at the switch. For a brief moment, of course, just to check.
But if system is overcharged, comp will not kick in. Been there.
 
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Old 06-26-19, 02:38 PM
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I did not fill the compressor with oil but I did add oil to the Freon when charging. When you say shorten the terminals on the pressure switch what do you mean?
 
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Old 06-27-19, 03:10 PM
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Well, that might just be your problem - not having it filled with oil. It's like bleeding master cylinder on the bench, before installing it. Each compressor MUST be filled with special oil before installation. They are very particular about that.
From what I remember, and it's been a while, pressure switch plug has 2 prongs. We'd run few spins of thin wire at the base of those prongs, thus shortening them, then reinsert it. When you start AC then, system believes that pressure switch is ON and should kick compressor ON. That's what we did to fill empty systems or ones that were very low on freon. Using compressor as suction device, as otherwise it will not start and you can't put freon in. Times when we did this in the cul de sac.
 
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Old 06-27-19, 03:30 PM
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Thanks for the help ukrbyk and alan73. I never took the compressor off the vehicle. So by vacuuming the system it took the oil out of the compressor? Do you think I should get a new compressor to be safe? Thanks.
 
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Old 06-28-19, 02:08 AM
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really havent given us much to go off of, but pulling a vacuum on an empty system does not remove oil, when reclaiming Freon from a system there is a chance to remove oil if you do it to fast but doubtful you have a Freon reclaim machine not even sure if you have manifold gauges, but without high and low pressures and knowing if the compressor clutch is engaging or not really cant give you any advice.
would suggest seeing a shop for diagnosis would just tell them exactly what you have done to it the discharge hose was leaking not sure if it was rubbing on something causing the hole or if pressures where excessive for some reason.
 
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Old 06-28-19, 07:13 AM
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Ac guage test

If you hook a guage set to it and you put some refigerant in it on the low side then see if the compressor clutch kicks on if it does go and close off the fill line and open tbe high side and see if the high side is building pressure if it does not if the compressor does not kick on when you add refigerant then its probably a clutch or even a bad pressure sensor
 
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Old 08-11-19, 06:36 AM
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There is a decent chance you could have a blockage. It would be standard protocol to install a new orifice tube or expansion valve and dryer after a system has been opened whether by damage or for repair. I will recommend a complete flush of the system as well.
 
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