AC Noise after DIY AC repair - Jeep Commander Forums: Jeep Commander Forum
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post #1 of 3 (permalink) Old 06-23-2014, 03:23 PM Thread Starter
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AC Noise after DIY AC repair

2010 Jeep Commander Sport
3.7L/NAG1 QT1
AC system has the rear AC in addition to front

My evaporator developed a leak, then the compressor seized.

I did the repair myself on the cheap, using a pretty weak set of AC tools.

Replaced the evaporator and compressor (rebuilt), as well, the recommanded parts after a Compressor seizing, the Condensor, both front/rear expansion valves and the filter/drier. Flushed out all oil/debri, added the spec amount of oil, vacuumed down in excess of 1/2 an hour, and added the spec R-134a charge. The rebuilt compressor instructions stated to add the spec amount oil to the compressor in addition to the 1.5 oz of Cool32 already in the compressor from the factory, which I did, so there may be an extra 1.5 oz of oil.

The first day, I got a DTC for AC pressure to high, I monitored it with my Autoenginuity and it did seem higher than spec, released an oz R-134a and the DTC never came back and the pressures read within what the FSM says for the conditions. Might be because of the extra oil in the system forced me to reduce the R-134a charge an oz, or maybe I overcharged an oz more than I should, remember I improvised with some pretty cheap and old tools. Eitherway that does NOT seem to be a problem now. The AC blows very cool, it seems to be holding pressure and NOT leaking.

But the AC system is making noise now, every once in a while I get a fluid rushing through a tube noise and/or a creak/moan for a second or two. Its only when the AC is on and has built up some pressure. It most likely happens when the car shifts its weight, accellerating/decellarating, going around a turn. It has only happened once from the front of the AC system, every other time it is near the rear. I.e. Only once from the front evaporator/expansion valve and all the other times it seems to come from the long tubes running to the rear and/or the rear evaporator/expansion valve. Turning on the rear AC seems to reduce how often the noise happens.

I suspect it might be extra oil collecting in the long lines to the rear, that it built up and got pushed through the system like a shot, maybe force its way past the expansion valve. I was hoping the oil hadn't circulated all over the system yet and I was getting some build up pushed through making noise, until it got more evenly spread through the system. Anyone have enough AC repair experience to confirm that?

The rushing fluid sound in the lines seems to have gone away now, and I've been operating the AC enough, to include running the rear AC, over the last couple of days that it has got have fully spread out by now. Its just seems to be a creaking/moan from the rear expansion valve every once in a while. Is this the sign I may have a bad expansion valve out of the box? Or maybe damaged it with a slight overcharge or a little extra oil in the system?


-------Extra Details------
All the new parts were Four Seasons, except the condensor which was Spectra. They looked to be good quality, but NOT as good as the OEM parts they replaced.

Four Seasons recommend to add the full amount of oil to the 1.5 ounces of Cool32 lubricant that was already in the rebuilt compressor. So if anything I have extra oil in the system, but no more than 20% over the spec amount of oil, we're talking an extra 1.5 onces. I did NOT have an accurate way of measuring the R-134a weight, but the spec amount is 2 oz shy of 3 cans, and there seem to be 2 oz left in the last can before I stopped charging.

Yes, I flushed all the lines and remaining parts, heck even the new parts just to be sure. But, since this is a DIY repair on the cheap, I used 99.1% Isopropyl Alcohol and then Non-Chlorinated Brake Cleaner as the degreaser/solvent/flush with compressed air, NOT to mention giving them a full day open to low humidity air to make sure everything evaporated out. NOT the approved flush, but both evaporate quickly with no remaining residue and the compressed air helped. I also vacuumed down the system, reapplying vacuum several times for 2 hours in case there were fumes of these flush materials still left.

My gauges were cheap to begin with 10 years ago, they leak slightly and I'm NOT 100% confident they are fully accurate. I could NOT get the system to hold a vacuum, I was pretty sure because of the cheap gauges connected to the system was leaking, but I keep the vacuum at 20-30" for an entire 2 hours by continuing to reapply vacuum on the system. The fact its been two weeks now and the standing pressures and operating pressures seem to be the same is pretty good evidence what I hoped was right and it was the gauges and their lines leaking the vacuum and NOT the AC system.


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post #2 of 3 (permalink) Old 06-26-2014, 10:22 AM Thread Starter
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An update, in case someone with a similiar problem searches and finds this thread.

Since this is a more generic AC question, than it is a specific Jeep Commander question, I also posted it that www.allpar.com forums. That should be a resource for everyone on this sight. Might NOT be as good for Commander specific advice, but if you've got questions or problems with more general things that all Chrysler/Jeep/Dodge have in common, like engine/trans/AC, etc, you can ask them there as well and get a bigger pool of knowledge.

Some knowledgeable people have confirmed for me, that too much oil in the AC system can cause these noises.

But, first thing recommended is to do an accurate measurement of the high/low side pressure of the AC according to the procedures in the FSM and check those pressures against the FSM specs. This is best indicator to tell if the system is over/under serviced with R-134a or if there is some sort of malfuntion with the parts in the AC system. Once that all checks out, then the following are possible causes.

To much oil in the AC system (I know there is at least 1.5oz more than spec in the system, either Four Seasons instructions for the rebuilt compressors is bad advice or the instructions are so vague, I misunderstood them). I guess the lesson is, if the spec is 7.5oz of oil for the system, then have 7.5oz of lubricant in the system, NOT more or less.

There is no oil drain on the AC system, I will have to open the lines to drain some oil (remember you have to properly remove the regrigerant from the system before opening it) If you open an AC line under pressure (and they are under pressure even when the system is off) it will burst open (with risk of injury) and tons of refrigerant will rush out spraying everywhere carrying lots of the oil with it, and then you have no idea how much oil is left in the system. And everytime you open the lines, you're suppose to replace the filter drier, which the filter drier should have some trapped oil in it that you have to replace when installing a new one. I have to look up the specs for the trapped oil, but just replacing the filter drier should get me close to proper level of oil in the system.

Finally, if that does NOT work, then I must have gotten a bad rear expansion valve and its noisey, so I will have to then replace the rear expansion valve.


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Last edited by Mongo; 06-26-2014 at 02:00 PM.
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post #3 of 3 (permalink) Old 07-08-2014, 08:18 AM Thread Starter
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I replaced the Filter/Drier this last weekend. The FSM spec is that the Filter/Drier traps 1 oz of oil in it, thus if I replaced it dry and do NOT add oil, I should have reduced the oil charge in the AC system by 1 oz.

Unfortunately, the lines and rest of the system are just too difficult to disassemble, I tried to turn the compressor by hand, with the discharge hose disconnected at the condenser, hoping to pump out a little more oil, but it didn't work. The pressure hose has an upward bend in it and that doesn't allow for compressor oil to have a full downward path to drain.

The noise improved, less frequent and less sever, but its still there.

By my calculation I am still 0.5 - 0.75 oz over the specified amount of oil in the system.

Since I did NOT drain the oil out of the rebuilt compressor and went with their word in the instructions that it had 1.5 oz of ICE32 in it, I may have even more oil in the system. The manufacturer is "4 Seasons".

I'd only suggest for anyone else, follow the universal instructions. When you replace a compressor, you're suppose to drain the oil out of it, that came with it, and then add the recommended amount of oil in the FSM. "4 Seasons" instructions said, it has 1.5oz of ICE32, don't drain it and add the FSM specified amount of oil. Which is rather vague, I assumed it meant add the FSM Spec amount of oil already ontop of the 1.5 oz of ICE32 already in it. I think its suppose to be add the spec amount of oil minus the 1.5 oz already in the Compressor.

As well, I may just have a faulty expansion valve, either bad out of the box or I damaged it with too much oil in the system.


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