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VW MKIII-A3/B4 TDIs This is a discussion about MKIII-A3/MkIII Jetta/Golf (<99.5) and B4 Passats (96,97) TDI's. Non TDI related postings will be moved or removed.

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Old September 13th, 2017, 13:38   #1
ejallison1
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Default AC Questions B4

Am repairing AC since radiator sprung a leak.

Putting in new:

Condenser
Air Drier
Expansion Valve
New seals on above

I've heard about the "black death" but this is my first go around with AC system other than using gauges to charge the system. The little bit of old PAG 46 oil I see draining from the old condenser is black but I am not seeing any aluminum flakes or streaks in it. Is that normal? The whole system was changed out by previous owner about 6 years ago and car has had little AC use since then.

AC compressor has never made any funny noises. Would not charge up completely earlier this summer. Low was a little high at high 30's and high side would go to 150. Although it did cool better it was still not cold enough.

Thanks
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Old September 13th, 2017, 14:03   #2
Windex
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Define "would not charge up"

The low side of an A/C system can more than accommodate a proper charge and then some. If the car would not take a full charge, then something is not quite right.

I have seen black AC oil - not great. If you are going to the extent of replacing all those parts, it would be a good idea to remove the compressor from the car, and tilt it upward to drain as much of that blackish oil out as you can, then replace with new PAG oil.
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Old September 13th, 2017, 15:27   #3
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Thanks Windex. Just got off the phone with PolarBearinc.com and am having a new aftermarket compressor shipped. They warned to thoroughly clean the lines with the non-mineral oil based cleaner. Said the good stuff was highly flammable. According to them if oil is black it is not good as you mentioned.


I could not get the ac system in the 20's on the low side and 200's high side and I patiently waited to empty the can(s)-just wouldn't take a charge. Ambient temp was in high 80's F.
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Old September 15th, 2017, 08:24   #4
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Quote:
Originally Posted by ejallison1 View Post
Am repairing AC since radiator sprung a leak.
so this is your engine radiator or your AC 'radiator'(youd mean condenser)
from what your saying youve got problem(s) you need to trace down. new parts may do it. it may be compressor, or any one or more parts. you have quite a few. of course finding why you have contamination,black oil will help, perhaps be your (underlying) problem..?.
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Old September 15th, 2017, 23:55   #5
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The engine radiator sprung a leak so since I had to take the front end off to replace it I decided to fix the AC as well. AC has been out for a year or better. Awaiting new compressor arrival and flammable AC Flush. Have in hand the expansion valve, air drier/accumulator, new condenser, new hi low switch.
Have tested the fan and the fan control module which are working correctly. Will need to flush lines and install.
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Old September 16th, 2017, 05:56   #6
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In addition to the lines, flush the evaporator and the new condenser.

-Todd
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Old September 21st, 2017, 21:26   #7
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This is my first rodeo with the AC so am a little curious as why to flush a brand new condenser-just to make double sure it is clean??
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Old September 22nd, 2017, 12:42   #8
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I didn't flush anything on the B3V but that's a risk I was willing to take given that all the AC systems that donated parts were sealed when I pulled the parts and ends were capped immediately.

The other reason I didn't flush was that the flushing chemical I looked at said do not use on condenser or evaporator or lines with accumulators so in the end my feeling was why bother since I would have been able to use on just two lines only, so I passed. It's also expensive as chemicals go.

In the end I replaced all the o-rings and the drier but settled for used bits for everything else.

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Old September 22nd, 2017, 17:06   #9
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Quote:
Originally Posted by ejallison1 View Post
This is my first rodeo with the AC so am a little curious as why to flush a brand new condenser-just to make double sure it is clean??

Although new, I doubt that condenser was built in a super clean facility. There's always the chance that swarf, dirt, flux, etc are in it.

If you're changing the compressor, drier, TXV and condenser, the system will be almost completely disassembled... you have the chance to clean to bare metal.

It's a lot of work, but sometimes it's worth it to do it once and not worry about it for a while.


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Originally Posted by Steve Addy View Post
It's also expensive as chemicals go.

Very true, which is why I chose to use acetone. When I dove in head first, I did a lot of reading. A lot of techs were recommending brake clean, xylene, acetone, etc.

I split the gallon and use the first half for the initial flush. It gets the main filth and oil out, and it gets dirty fast.

The next half also gets split... first half is the 2nd purge and the last is the final. If it's still dirty flush again. Follow up with compressed air.

If you want to be super meticulous, follow up with denatured alcohol and compressed air, to pull the moisture. You should deep vacuum, but the alcohol will give you a head start.

-Todd
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Old September 22nd, 2017, 23:41   #10
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Quote:
Originally Posted by ToddA1 View Post
Although new, I doubt that condenser was built in a super clean facility. There's always the chance that swarf, dirt, flux, etc are in it.

If you're changing the compressor, drier, TXV and condenser, the system will be almost completely disassembled... you have the chance to clean to bare metal.

It's a lot of work, but sometimes it's worth it to do it once and not worry about it for a while.





Very true, which is why I chose to use acetone. When I dove in head first, I did a lot of reading. A lot of techs were recommending brake clean, xylene, acetone, etc.

I split the gallon and use the first half for the initial flush. It gets the main filth and oil out, and it gets dirty fast.

The next half also gets split... first half is the 2nd purge and the last is the final. If it's still dirty flush again. Follow up with compressed air.

If you want to be super meticulous, follow up with denatured alcohol and compressed air, to pull the moisture. You should deep vacuum, but the alcohol will give you a head start.

-Todd
I bet you meant to qualify the compressed air as filtered compressed air, correct?

The reason I ask is I can't see much benefit to using standard compressed shop air to clean lines when there's oil and/or moisture in it?

Most of us don't have access to paint booth quality compressed air, but I'm sure that's what you mean?

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Old September 23rd, 2017, 15:36   #11
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Somewhat.... I priced all that fancy stuff and realistically, it was too much for my needs.

My compressor is mounted high in the garage. I've got the main drain on a 6' dirt leg, with purge valve. From the leader, it goes to a water separator, then through (4) 4' vertical runs, each with a dirt leg and purge valve, then to the reel.

I blow out everything, then run a disposable filter at the end when I'm doing stuff that matters. FWIW, I've never seen junk make it through when I'm painting, never seen fish eye, etc..

I've considered installing another dirt leg and water separator at the reel, but I really haven't seen the need.

I think it's working...

-Todd
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Old October 21st, 2017, 22:30   #12
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Finally getting around to finishing this project on the AC on this B4. Have been flushing the AC lines and the evaporator-everything else is being replaced. I have a question regarding the Pag46 oil and where it should be added. Should it all be added to the compressor or distributed to the different components as described below. Several threads state that the correct amount of PAG 46 oil is 4.6oz. so that seems correct but also found this info in a thread: http://forums.tdiclub.com/showthread...light=ac+pag46 Post #7
From the Bentley, the total amount of oil needed in the system in 135cc plus or minus 15cc (4.6oz plus or minus 1/2 oz).
When you discharge an AC system, the oil falls out of suspension (so to speak) and is distributed in the various components of the system.
Per the Bentley, oil is distributed as follows:
Compressor 50%
Condenser 10%
Suction line 10%
Discharge line 0%
Evaporator 20%
Receiver-drier 10%
When you replace a component, you lose the oil that was in that component. You should add back into the system whatever oil was lost.

When rereading this it seems the oil should only be added to the compressor but just that if a particular component is replaced to only add back the oil normally found in that component. Since I need to add the whole 4.6 oz it all should be placed in the compressor-right?
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Old October 22nd, 2017, 05:53   #13
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Distribute the oil.

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Old October 22nd, 2017, 17:07   #14
iluvmydiesels
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thats an old A/C installers problem. have a new compressor, it can be full with all the systems oil, the a/c will still have oil in it. as you run it it will have that much oil in it, later you wonder why it blows.
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Old October 22nd, 2017, 17:52   #15
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OK Thanks-will distribute the oil by percentage to each component as listed above and then pull vacumn for 2-3 hrs after getting everything reconnected-last thing to connect will ne the receiver/dryer. Everything has been flushed that is not brand new and the new compressor has been emptied of oil it came with.
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