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View Poll Results: Replace ac drier when replacing compressor?
Yes 6 75.00%
No 2 25.00%
Voters: 8. You may not vote on this poll

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Old April 8th, 2020, 13:09   #1
Matthewsz
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Question 09 Jetta AC Receiver Drier

Hey all. My ac was barely working, tried having it refilled at a shop and after vacuuming, it would take even less refrigerant than what was in there before.
So I have the new compressor already, and I know the proper thing is to replace the drier when the system gets opened up. However I've heard several people say, if the compressor didn't fall apart (which I don't think is the case), I should be fine with the old drier. What do you think?
It's not the cost of the drier, I just rather not pull the front apart if the new one won't make a difference. The compressor can be changed without touching the front but the drier is impossible to get to without cutting some of the carrier and that's not something I prefer to do.
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Old April 8th, 2020, 14:54   #2
BuckeyeMan71
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Quote:
Originally Posted by Matthewsz View Post
Hey all. My ac was barely working, tried having it refilled at a shop and after vacuuming, it would take even less refrigerant than what was in there before.
So I have the new compressor already, and I know the proper thing is to replace the drier when the system gets opened up. However I've heard several people say, if the compressor didn't fall apart (which I don't think is the case), I should be fine with the old drier. What do you think?
It's not the cost of the drier, I just rather not pull the front apart if the new one won't make a difference. The compressor can be changed without touching the front but the drier is impossible to get to without cutting some of the carrier and that's not something I prefer to do.

There should be a little filter in the dryer that needs to be cleaned


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Old April 8th, 2020, 17:32   #3
tadawson
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The issue is mainly the dessicant jn the drier getting moisture in it when the system is open to change the comp, and about the only was to even think about that would be to remove, oull a vacuum on, and cap the existing drier, which is more work than replacing it.


On the more practical note, if the system has never dropped to atmospheric pressure, and you can flip the hoses and get vavcuum back on it quickly, you might be OK . . . the downside being that if not, you are doing it all over.


As far as a filter, unless the compressor has physically failed, that would not worry me. There should be no particulates in a *properly working* system. The issue here is that that is not the case, and I don't think the failure is actually known, so crud in the system *IS* a possibility.
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Old April 8th, 2020, 22:23   #4
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I have to disagree with previous assessments.

Beginning 2006, the compressors change from a clutch driven unit to a system that the compressor is run by a variable valve. The variable valve is a well-known failure point. I doubt the compressor needed to be replaced.

There are two types of valves. One has a bolt to hold it in and the other has an internal snap ring. That distinguishes between the two types. There are lots of CRAP replacement valves, but you need to find one with the filter screen. As for the desiccant, it's usually a good idea to replace it, but we have replaced the variable valves without bothering the drier.

The system needs to be evacuated in order to replace the variable valve. Even then, the valve may hold back some pressure, so it needs to be removed carefully.

Since you replaced the compressor, which already has the variable valve, I'd just put it in and vacuum the system. Recharge and move on.
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Old April 9th, 2020, 03:46   #5
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Nitrogen purging while installing the dryer new is the only way to do it. The
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Old April 9th, 2020, 04:44   #6
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Quote:
Originally Posted by Franko6 View Post
I have to disagree with previous assessments.

Beginning 2006, the compressors change from a clutch driven unit to a system that the compressor is run by a variable valve. The variable valve is a well-known failure point. I doubt the compressor needed to be replaced.

There are two types of valves. One has a bolt to hold it in and the other has an internal snap ring. That distinguishes between the two types. There are lots of CRAP replacement valves, but you need to find one with the filter screen. As for the desiccant, it's usually a good idea to replace it, but we have replaced the variable valves without bothering the drier.

The system needs to be evacuated in order to replace the variable valve. Even then, the valve may hold back some pressure, so it needs to be removed carefully.

Since you replaced the compressor, which already has the variable valve, I'd just put it in and vacuum the system. Recharge and move on.
^^^this^^^

Your RCV was likely bad, although I would also like to use the car's own OBD to verify the system's function as well as making sure both fans work.
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Old April 9th, 2020, 06:06   #7
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Of the hundred of AC systems I have repaired I have learned this: slap a compressor on it and see it back next year to do it again (or in the fall if you do it early spring). Replace the drier and flush the system and never see the car again (for AC problems).

First off replacement (OEM) compressors come with a full system charge of oil. You will need to drain off the extra to match how much should be in the compressor.

Most aftermarket AC compressors are sold no warranty if you don't replace the drier.

The compressor may not blow apart and send shrapnel through the system, but it is a moving part and does wear. I have seen plenty of expansion valves absolutely coated in grey residue. A couple were actually failed from the amount stuck in them.

As far as the N280 control valve in the compressor - if it was a 2 year old car with 50k miles then I would slap a new valve in it. But you have a 2009. By this point I would be suspecting worn pistons, week reed valves, and overall worn out compressor.

As far as the drier - a lot of failed compressors appear to be from descant balls when the drier sack bursts and they get lodged everywhere. A drier is cheaper than a new condenser AND compressor. As far as why? The descant bag failures were on unopened systems. No repairs or even a recharge. Your guess is a good as mine why THAT happened.

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Old April 9th, 2020, 17:37   #8
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Thanks everyone. Is there a difference between aftermarket and oem driers? There's also OEM new old stock on eBay for ⅓ the price, is that a bad idea?
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Old April 9th, 2020, 19:37   #9
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when it comes to AC, buy once cry once. 1/3 the price means 1/100 the life of the part when it comes to this sort of thing.
filter dryers do one thing and ONLY one thing. absorb moisture in the system. that's it. nothing else. and it usually is trashed the moment you start up the system. if you take the plugs off it for more than a like a minute, its trash. they come filled with dry nitrogen. once air gets in, the job it has, has been done but not to the AC system, but to the air. the ONLY proper way to install a filter dryer is to go ahead, do your thing to the system( flush, clean, new parts ect... but leave the old one in place. once ready to take a vacuum, push a charge of nitrogen though the system first, after a nice blast of dry nitrogen, and as its slowly trickling out of the shrader, crack off the lines to the dryer and install it so that the nitrogen flows into the dryer as its installed. hook it all up then turn off the nitrogen and pressurize the system to its MAX PSI with nitrogen and check for leaks and let it rest for an hour and see if the gauge moved at all, if it moved more than 1PSI in an hour, you have a leak. you can save the dryer as long as you leave nitrogen in it and do the repair till no leaks. pull a vacuum with a micron gauge down to 500 micron, 250 preferably. if you have a leak you will never get that low. charge up and your done.
doing anything other than this will mean much less if only a season at best. the rest of the ac system is really easy, replace parts, flush lines with evap purge or a flush kit. new PAG oil measured out into whatever compressor you get (oem is IMO the only way) i don't trust the oil levels in them. easy as cake to drain and fill properly. replace all o'rings on any connection to pull apart.
IMO its worth paying someone to do the job properly with a guarantee. unless you have the micron gauge, nitrogen tank & regulator, vac pump, manifold gauge,
the cost of a micron gauge is more than the service its self. pump and gauge are cheap, about $200 for a DIY once and done job tools. (oh and btw the cheep micron gauges dont ever work, dont waste money on them. $250 buys a decent one that will work.

IMO just take it in. to do a proper job that will last costs more than the service.
all the jobs i have done with AC on cars cost about 2 hours of service to do the job. my first DIY cost me $450 just in tools.

Last edited by Mongler98; April 9th, 2020 at 19:40.
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Old April 10th, 2020, 04:45   #10
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Quote:
Originally Posted by Matthewsz View Post
Thanks everyone. Is there a difference between aftermarket and oem driers? There's also OEM new old stock on eBay for ⅓ the price, is that a bad idea?

The drier on that car is inside the end of the condenser on that car, and do not always want come out.

A condenser comes with a new one already installed, and is not that much more money.

However, you do not need it. You likely never did. You just had a bad RCV. Which means your compressor never "failed", and therefor never send any debris into the system in the first place.

The RCV is old news, well documented here, and literally years after everyone in the aftermarket world knew about it, and had successfully replaced THOUSANDS of these things, Volkswagen themselves finally came out with an official TSB about it. And offers the RCVs by themselves too.

I buy the RCVs usually five at a time, and I probably install 20+ every year, for the past several years. I always have them on the shelf.
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Old April 10th, 2020, 09:27   #11
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I still have the compressor in the box so I might return it if replacing the RCV does fix the problem. Sounds almost like the door latch problem where most people just replace the whole thing when really all it needs is the tiny motor cleaned up for free...
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Old April 10th, 2020, 09:59   #12
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That would definitely be the best plan of attack
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Old April 11th, 2020, 00:36   #13
Matthewsz
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And what's the difference between a $15 eBay and a $70 polar bear? There are tons of positive feedbacks on the cheap ones.
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Old May 21st, 2020, 20:02   #14
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Changed RCV, system struggled to accept the specified amount of gas, compressor would not start to work. I don't know the physics behind it, could it be that I received a faulty new RCV? Supposedly it's OEM but the shape is longer.
Not wanting to waste more time (which I think I still did by replacing the drier that had almost no dirt in it), I replaced the compressor with the rebuilt one, system charged without an issue, AC blowing cold now.
Thanks for all the tips, what should I do with my old compressor and new RCV that I can't confirm if it works?
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