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teb65
Novice
Sep 7, 2008, 6:16 AM
Post #1 of 14
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ac compressor problem
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The ac was not cooling, the low pressure wasabout 80 and the high pressure was about 150. The shop manual directed me to the orifice tube, I changed it but nothing else changed. The next thing was buy another compressor. I installed the compressor after adding the oil (2oz) then evacuated the system for about 3 hours. I closed the valves and let it sit for about 2 hours with no vacuum loss. I purged the gauge lines and added refrigerant. The first can went in fine and the pressure was starting to come up.While adding the second can of refrigerant the compressor began to knock. The system should hold 2.2 lbs . At first I thought the clutch was hitting something (sounded like a card in a bicycle spoke). If I leave it low on refrigerant the knock will only be there for about 10 seconds, but if I try to get close to the full amount it makes the sound constantly. I have tried a couple of times to evacuate the system and start over incase I missed something, but it happens every time. with about 2/3 of the charge in it is putting out some cold air. with only one can in only the passenger side will start to become cool. Seems that if the high side gets to about 180 or so it the compressor starts the knocking sound.
2002 oldsmobile intrigue
6 cyl 118,000 miles
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Tom Greenleaf
Ultimate Carjunky
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Sep 7, 2008, 6:58 AM
Post #2 of 14
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Re: ac compressor problem
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Arggh - Here come the questions......
1. Just how did you change the "O" tube and what did it look like coming out? Did you pull a vacuum and add the correct charge then?
2. Compressor. This counts! How much oil came out of the old one and how much was in the new one? These could be lots to near none. Did you spin the new compressor by it's shaft prior to installation? If no oil present they will self destruct in no time - sorry to say
Oil: Oil is moving throughout the system when operating. When off it settles where it may in assorted parts of the system and there are educated guesses as to which part would hold how much of the 9 ounce PAG 150 charge this car calls for. Compressor would be - what came out (measured) plus 1-2 ounces for a replacement that was drained first as you can't know for sure how much or what type may have come with it without simply using your own new.
More on oil: It only moves when there's adequate charge of refrigerant or it just sits there where you left it. Oil isn't really moving till system can make some cooling noted at vents.
3. Did compressor stay engaged with your first observations? Does it now?
This noise issue is NOT a good thing but let's see what we can do,
T
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teb65
Novice
Sep 7, 2008, 7:06 AM
Post #3 of 14
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Re: ac compressor problem
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I pulled the tube by disconnecting the condensor tube. it broke as I pulled it out(it's plastic) and yes I pulled a vacuum the recharged.
About the same oil (2oz) came out of the old one and yes I spun the compressor ten times as they said to in the manual (could have been more but at least ten.
Everything appears to be working normal. At first I put some freon in under the vacuum, then started the car. As the pressure came up the compressor engaged and stays engaged, no cycling. As more refrigerant went in the car began to cool off. The temp out of the vent was about 60. When the knocking started I stopped adding to see what was happening. I let it sit until I could talk to some people. The next day I tried to run it a little and only the passenger side cooled off. Still did the knocking. I am not running it because I'm not sure of what damage is being caused.
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Tom Greenleaf
Ultimate Carjunky
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Sep 7, 2008, 7:36 AM
Post #4 of 14
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Re: ac compressor problem
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Good so far I think - don't operate system again right now.
What did the old orifice tube look like at its screen? Also was the oil burned looking coming out of old compressor?
What is your best guess as to how much oil is in this system now?
T
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teb65
Novice
Sep 7, 2008, 7:42 AM
Post #5 of 14
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Re: ac compressor problem
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The old orifice tube did not have a screen it almost looked like a styrofoam material. The oil out of the old compressor was a greenish yellow, looked ok. I think they include a dye in the oil at GM. As for how much oil right now I have no idea. It should be the same as when I started. I added 2 ounces to the compressor and see no leaks anywhere. The system appears to be air tight. Could the reman compressor be bad? I have read that does not happen too often.
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Tom Greenleaf
Ultimate Carjunky
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Sep 7, 2008, 9:00 AM
Post #6 of 14
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Re: ac compressor problem
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Reman compressor could be bad. Any chance clutch is making the noise and not the compressor itself in your opinion? The yellow/green would be dye and was used in some GMs from new. Not so sure about this descrition of "Styrofoam" as the O tube is a very fine mesh screen but could have just be oiled up. What you don't want is metal, pepper like particles or black colors = "black death" which requires a total system flush out and I don't know if this condenser will flush out as some don't.
I think this is a "variable" rate compressor and pressures are elusive diag info on those and they will stay engaged at very low, low pressure side and I think it also senses temp thru perhaps a "thermistor" ..
Oil: Seems like you are within a couple ounces of when this system was operating properly before anything was touched - correct? That's good. I was worried about the chance this was choking on oil.
Notes: Compressors make noise when oil isn't getting to them, low charges sometimes, refrigerant overcharges (not the problem as I see it for this), plain worn/defective and could with choking on oil which isn't an exact science but thought that most will toss extra oil to accumulate in condenser and reduce performance and give strange operating pressures.
When adding refrigerant, just how are you doing that? 12oz cans or something else? If something else please say what's in it and the listed weight of contents.
I'm confused about this noise as you are. Worried that this one could have made a debris field that original apparently didn't - dammit! You observed 60F vent temps while you are pretty sure you still weren't fully charged which could be just momentary while adding refrigerant. When adding refrigerant it's best to get what you can into the vacuum first which can be perhaps 1/3 of the charge depending on how done. From there you add in spurts and watch pressures even with knowing amounts added along the way. It takes a short while for system to stabilize. There's a direct pressure/temp ratio with output temps and low side pressure observations. To see 60F at a vent suggests low pressure was at mid/low 40s at the moment that occured.
Gotta ask as this may be a different set up - Does this use a low pressure, two wire cut out switch which normally would be on or near the accumulator on return side? Need to know that but it still doesn't explain the noise - for the moment I just don't know why that's happening,
T
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teb65
Novice
Sep 7, 2008, 9:15 AM
Post #7 of 14
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Re: ac compressor problem
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Its very hard to tell what is making the noise. I see nothing external that it could be (yet). I know it starts and stops with the compressor. I checked the air gap and that was fine. It really sounds like a loud valve tap actually. It increases and decreases with RPM.
oil should be closed to original but I have no way of knowing actually. Afraid to add more oil, don't want too much but I also don't want too little.
I have heard that ac systems do wierd things when under charged. General consensus was to fully charge to see what happens.
I am adding refrigerant by 12 ounce cans. The first one goes in under vacuum or most does. I have read that the first can should go in as liquid, although I did not do this because of being uncertain. I just kept the can upright.
You are correct, the pressure was about 40 when I had the 60 temp. High side was about 200 or so, can't remember ambient now.
The reason I said I did not have full charge was I am expecting about 3 12 ounce cans to go in. I have only gotten about 1 and a half cans before the noise starts. When the compressor first comes on during charging it is very quiet. It will act normal until the high side gets around 180 or 190 psi.
There is a swith near the accumulator (2 wire) not sure if it is temp or pressure.
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Tom Greenleaf
Ultimate Carjunky
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Sep 7, 2008, 9:54 AM
Post #8 of 14
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Re: ac compressor problem
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Ok: The switch is a LPCO and this a CCOT system as best I can tell. That switch will disable compressor when pressure is too low - indicative of temps too low to need compressor or low charge - it's basically that simple.
So far your work seems careful and right on. Agreed - counting 12oz cans for this system takes out the guesswork or weighing which is handy. I wanted to rule out sealers and other stuff some larger cans use that cause more troubles than they could ever fix.
I don't think you are low on oil nor too full to be the issue??!!??
Note in here: High side pressure should end up about 2.2 X ambient temp in front of condenser in F. It's curious that you are so high with this short of a charge but it's also fan related which must be on and idle should be raised for readings to about 1,200 to 1,500 RPM. Misting water over condenser is like a more effective fan for testing.
Sorry this is getting elaborate so quickly - I'm trying to envision what you are doing and using for equipment. Air in system will mess up a show like a f*rt in church during a moment of silence!
I'm hoping you are using a can tap with a yellow hose that will go thru your gauges. With each time hoses are removed or if you are switching between gauges and can there's air getting into hoses of the tap line and gauges if disconnecting + connecting all the time. If something like that you must spit just refrigerant thru the lines where there's any chance air could have entered. That's enough to mess it up fairly fast - still doesn't explain the noise but could explain early high side pressures which I'm about to say is a bad compressor getting higher on the possibility list - arggh!
Mid note: You can add liquid to the vacuum by holding can upside down with engine off. It will just evaporate instantly. Cans get cold when giving up their gas and they do need to be kept warm. Water not too hot to handle will warm cans ahead of time and during charging. Warmth from your hands can do - things do slow down as pressure of suction side is equal to can pressure when nothing exchanges.
I'm a bit undecided on suggesting you run this again with the noise right now as if there's a defect it might be early enough to not have a disaster.
It was quiet at first start up and low charge which is reassuring for now. As the compressor works harder it would aggrevate itself if a problem or any other reason for the noise like if it's mounted properly will all brackets in place and tight. Belt tension proper should be known and sometimes belts can be the noise and sound like real mechanical problems. A spray of WD-40 on a noisy belt - when it is the belt or pulley shinniness or whatever causing the issue will shut them right up for a while and I don't mean with a belt slipping which if a lube is used should cease slipping quickly. While on that subject - is belt properly on, on every pulley?
Hey - Can you tell I'm concerned about the noise!? I'm still worried about running it again to even test as I'm not there listening to it myself to know if it's worth risking again.
Look for a PM (private message) coming soon,
T
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teb65
Novice
Sep 7, 2008, 10:13 AM
Post #9 of 14
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Re: ac compressor problem
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I am using a set of manifold gauges with a center yellow hose and being extremely careful to purge the lines prior to connecting to the ac, hoping this eliminates all possibility of air. The last time I evacuated the system and performed another try at it I had everything connected low side to the car yellow hose to the can with valve and high side hose to the vacuum pump. after evacuation I closed the high side valve and monitored the vacuum, then released refrigerant into the system. I am pretty sure there is no air in the system. If I leave the system partially charged then the noise is only made about the first few seconds until low side is pulled down and system stabilizes. Worse case scenario I will have to take the pump back and get another one. I just keep reading that most compressor problems are misdiagnosed.
Thanks for your help so far!
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Tom Greenleaf
Ultimate Carjunky
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Sep 7, 2008, 11:15 AM
Post #10 of 14
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Re: ac compressor problem
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Ok: You seem to have a good grip on this. I don't want to add my name to blaming it on a compressor so fast either. What really stinks is if you get another that does the same thing and then really have to question the diagnostics of it really being the problem.
In this 35.5oz system with a low charge and all other things operating properly a compressor should actually show a near zero or even a vacuum on low side with it forced to engage. Forcing can be done by jumping a TWO wire LPCO at its plug but don't leave it on that way. Compressor running that low on charge is running dry or will soon which is why the pre spin with oil is always a must. I suggest going back and letting the cut out switch do its thing when at all possible.
There's a whole lot of what the pressures are telling you. If it can pull low on suction side and make substantial pressure on high side it isn't the compressor by itself not pumping. The noise is the tricky part. Why, Why, Why??
If O tube was plugged you'd see a high pressure on high too early and very low on low side. Both sides running too high suggests there's no evaporating going on like if O tube was missing or the pump just can't do squat and you are really just reading static pressures flailing with a failed pump.
If you are up to continuing with it as it is then just be ready to stop. Things should improve as it gets near the correct charge. Your call but if it's making noise try to get the pressures while it's doing that as important but risky information.
If you need or think this needs oil and without an injector it is available in 2+2 cans which is 2 oz oil and 2 oz 134a. About now only you can guess if it's possible to be way too low. My wild guess is that it wouldn't be making noise if only 1/2 of the 9oz listed capacity - that from a known empty system, deviod of all oil.
Keep at it and do let us know what you may find,
T
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teb65
Novice
Sep 7, 2008, 11:26 AM
Post #11 of 14
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Re: ac compressor problem
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I can continue adding refrigerant and watch the pressures, today it is only 78 outside so the pressures may be a bit lower. I would add some oil but what happens if you get too much? How much would be safe to add? as a guess!
the puzzling thing is the compressor only makes noise when the pressure is above 180 or 190. (high side):)
I just checked the static pressure (engine off and cool) the pressures are equal at about 75 psi - remember the outside temp is about 78 degrees. Could be a little cooler in the garage which puts my static pressure pretty close to normal.....
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Tom Greenleaf
Ultimate Carjunky
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Sep 7, 2008, 4:22 PM
Post #12 of 14
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Re: ac compressor problem
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You should be able to add what the system calls for and have kept fair track of so far. System should really operate with spikes of pressures over 300 at times with no explosions! Remeber - high side guess pressure is 2.17 up to 2.5 max of the ambient temp coming in thru condenser measured inches in front of it.
Note on static pressure and equalizing pressures: Pressure of 134a will be close to the temp when contained - in the car or in the can. ie: If the temp is 75F the pressure is about that. It deviates from that exact cross line coincidence when warmer or colder. Figure in some engine heat also effecting pressures. High and low sides are not perfectly sealed from each other and should equalize. Don't let a few psi worry you though and some take more time.
You really can get the pressure and know that state of the gas with an infrared thermometer on lines and parts and for that matter that tell the pressure of the little can as it gets colder you could calculate its exact pressure.
"Fun facts to know and tell, amuse your friends and appaul you neighbors if you will" 
T
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teb65
Novice
Sep 21, 2008, 2:22 PM
Post #13 of 14
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Re: ac compressor problem
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OK, I got another compressor, added the oil, and installed it. I put the system under a vacuum for a while then checked for leaks. Added refrigerant and the same noise came back! Looks like the compressor is not the problem. I have a full charge now, pressures are fine and air comes out of the vents cold.... but the clicking/knocking noise is back. It really sounds like a card in the spokes of a bicycle.
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Tom Greenleaf
Ultimate Carjunky
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Sep 21, 2008, 10:05 PM
Post #14 of 14
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Re: ac compressor problem
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http://www.autoclimas.com/...igerant%20charge.php
Bookmark that link as it's jammed with good info.
This compressor is a nightmare and I just am at a loss as compressor two makes this noise but seems to work properly. One sure would think that even if defective again it would at least have the courtesy of being defective in a different manner.
***********
As I see it from this long thread and history:
Symptoms of compressor unable to pull from low side and and cooling quit. O tube was clear, compressor replaced with two ounces of oil out and two put back spun in. Noise was noted early in charging as it began to cool.
Belt, mounting, clutch or another belt driven item seem to be ruled out.
Another new compressor installed and pressures and performance are right on (is this so?) but this "flapping" noise like a card in spokes persists when operating.
************
What are the current pressure at what temps and RPMs? Are you confident in the method used to weigh in the correct charge? Is there a bouncing needle on the gauge set now and was there before?
_____________
Hey - the chances of two bad compressors is unlikely but not impossible and it gets worse with freak problems and a third could do the same. At times like this with all the king's horses and all the king's men in order you would try another brand of reman or another brand of new.
I strongly suggest taking the car whole as is now to a shop that routinly does A/C so see this first hand themselves for a second opinion with the best history you can provide much of which is here. I don't know what I'm missing that might make itself apparent if I was witnessing this first hand.
If there's a chance that a muffler in hose has a flaw or a hose itself with an unseen flaw that doesn't leak and performs well with correct pressures and no odd pressures or bouncing needle on gauges seen this is a first for me personally.
Oil if wildly overcharged would cause issues. Usually poor cooling and quiet IMO then up to hydraulically locking compressor as would an overcharge. Under oiled makes noise at first much like the one noted! It doesn't seem to be a possibility with what I've seen so I'm relying on you.
There are possibilities of contamination by sealers (none mentioned) or perhaps dessicant blown loose from failed drier. This hasn't seemed to show up with the pressure which confuses the situation.
I don't know what I could have missed with this in assisting you to find out why this persists and again as said would like you to seek a hands on second opinion,
T
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