A/C Filtering Screen???

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
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97 Mk3
Do 1996 B4’s have any kind of filtering screen in the A/C system?
You talking about the cabin air filter? I think all B4 cars got the cabin filter that's out under the rain tray cover on the passenger side.

If you've never changed it get in there and do it, I'm sure it's probably full of debris by now. Every one I've seen in the JY's has been ignored.

And here's a tip for the Mk3 owners, all Mk4 cars got the cabin filter setup, and it fits in the Mk3 perfectly. No Mk3 4 cylinder cars came with cabin filter setup, only Mk3 six cylinder cars came with cabin filter.



The above photo shows the B4 cabin filter fitted to the B3V cowl, which is a direct fit.

Steve
 
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mustangmarty

Veteran Member
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Nov 9, 2016
Location
Central Texas
TDI
1996 Passat Wagon TDI
Thanks Steve, but I meant a filtering screen for the refrigerant in the AC system. Turns out there is no filtering screen. Only the receiver/drier which is also the filter for refrigerant. As far as the cabin filter goes, I have the same as in your pic. And your right, they fill up with dirt and leaves all the time.
 

Mongler98

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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
NO. Only a dryer, infact cars that DO have a internal screen, the upgrade is to buy a proper dryer filter and adapt the fittings. Screens often cause more problems then they solve in cases of failure vs protection. Remember that using nitrogen purge when installing a dryer filter is critical and is the #1 reason DIY jobs fail in a few years.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
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97 Mk3
NO. Only a dryer, infact cars that DO have a internal screen, the upgrade is to buy a proper dryer filter and adapt the fittings. Screens often cause more problems then they solve in cases of failure vs protection. Remember that using nitrogen purge when installing a dryer filter is critical and is the #1 reason DIY jobs fail in a few years.
With all due respect, isn't nitrogen purge really for AC system where the brazing on copper leaves scale inside the tubing? Or are you talking about some other product that purges out impurities in the lines? The only time I've heard of that is for testing pressure in the system so that refrigerant isn't wasted.

As for the filter adaptation sure, I doubt that it would hurt anything but if it really was necessary wouldn't the factory have installed a separate filter?

Steve A
 
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Mongler98

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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
With all due respect, isn't nitrogen purge really for AC system where the brazing on copper leaves scale inside the tubing? Or are you talking about some other product that purges out impurities in the lines? The only time I've heard of that is for testing pressure in the system so that refrigerant isn't wasted.

As for the filter adaptation sure, I doubt that it would hurt anything but if it really was necessary wouldn't the factory have installed a separate filter?

Steve A
Your right but it’s for much more.
So the dryer filter has a medium much like the white packets in food to keep them fresh, its job is to absorb moisture and ONLY moisture. In fact the filter dryer’s job is to filter out the contaminants from assembly and such when the system is open. The correct way to install a filter dryer is to have a trickle of nitrogen running through the system and you take off ONE plug and install then the other side so it was never opened to the air for even a moment. Those things are made at the factory with nitrogen in them so when you open it up and pull the plugs off it to install it sucks in moisture and air, this kills the filter.
The only way for a compressor to fail other than a defect is for a non-compressible thing like moisture or refrigerant as a liquid to pass through it, the filter does nothing to filter out debris from a compressor that is dying. Cut a filter open sometime and look at it, it’s actually free flowing. The gasses just pass by the filter medium. Think cherry bomb muffler.
 

oilhammer

Certified Volkswagen Nut & Vendor
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Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Do 1996 B4’s have any kind of filtering screen in the A/C system?

What is the context of the question?

Most any debris that could be damaging to the compressor will be caught up in the condenser (first), drier (second), expansion valve (third) or the evaporator (fourth), before it gets BACK to the compressor.

They do make aftermarket filter screens you can install, but I am not aware of any for this particular application and have never seen a need for one.
 

mustangmarty

Veteran Member
Joined
Nov 9, 2016
Location
Central Texas
TDI
1996 Passat Wagon TDI
I was asking because my AC isn’t working and every other auto AC system I’ve ever worked on always had an orifice tube filtering screen which is always the first thing I check.
 

oilhammer

Certified Volkswagen Nut & Vendor
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Location
outside St Louis, MO
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There are just too many to list....
I would say most cars use an expansion valve system, but there are a few orifice tube systems still out there (the B5 Passat is one such animal).

But that has nothing to do with why your system is not working. Diagnose it and go from there. You've started with Step R, go back to Step A. ;)
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
what pressures do you have at what temps outside, supper cool supper heat values are huge in diagnosing how to correct refrigerant levels. Also do an acid test and for the love of god do not add anything to your system other than 134a, no leak stop or crap like that.
You need a base line. What pressures (from a real gauge set) and how is the acidity of the PAG oil? those things are EASY to test. You should also measure the temps of the hoses coming into and out of the compressor, condenser and dryer. If your pressures are too high and your temps are too low going into the compressor, your running liquid into the compressor. Spend $40 at Harbor Freight for a gauge set, and the $9.00 at R.E. Michael for an acid test and a $5 temp probe for your multimeter, NOT A LASER temp gun. Report back.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
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Location
outside St Louis, MO
TDI
There are just too many to list....
what pressures do you have at what temps outside, supper cool supper heat values are huge in diagnosing how to correct refrigerant levels. Also do an acid test and for the love of god do not add anything to your system other than 134a, no leak stop or crap like that.
You need a base line. What pressures (from a real gauge set) and how is the acidity of the PAG oil? those things are EASY to test. You should also measure the temps of the hoses coming into and out of the compressor, condenser and dryer. If your pressures are too high and your temps are too low going into the compressor, your running liquid into the compressor. Spend $40 at Harbor Freight for a gauge set, and the $9.00 at R.E. Michael for an acid test and a $5 temp probe for your multimeter, NOT A LASER temp gun. Report back.

ROFL.... and there are Steps D through M, LMAO.... :D
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
yea ok, OP has a AC issue, temps and pressures are step A dude. B is an acid test, 12 years of HVAC experience here, in homes and buildings step a Is does it have power!

Whats step A for you? find the car, step B: find the keys???
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
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Location
outside St Louis, MO
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There are just too many to list....
No, Step A is find out what the actual complaint is, then find out if the compressor comes on.

12 years, that's cute. I probably have tools older than you, "dude". :rolleyes:
 

Mongler98

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Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
No, Step A is find out what the actual complaint is, then find out if the compressor comes on.

12 years, that's cute. I probably have tools older than you, "dude". :rolleyes:
congrats on that, im sure there is much more penis measuring you can do against me, but thats 12 years+ my 7 years of education and journeyman years.
 

mustangmarty

Veteran Member
Joined
Nov 9, 2016
Location
Central Texas
TDI
1996 Passat Wagon TDI
Low side is 80. High side is 50. So far I’ve replaced the expansion valve, RCV, filter/drier, and flushed the condenser, evaporator, and all lines. The oil that was in the system still looked new, so no evidence of any debris that I could see from a deteriorating compressor. But that’s the only thing left, so I’m trying that next. Strangest thing, the system would not even take any Freon yesterday. Like there’s no suction at all. And yes, I vacuumed the system down to 28hg and then let it sit for an hour and it held vacuum perfectly. Also, fans are working correctly and the AC clutch is engaging as it should, as are AC controls inside the cabin.

Is there any kind of test I can do with the compressor still in the car determine for sure if that is the problem? What about replacing the RCV with a 13mm bolt and nut? I know about the possibility of freezing the evaporator, but I’m in the heat of Central Texas and i would only run it for a few minutes just to see what it does.

What are the chances I replaced a bad RCV with a defective new RCV?
 
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compu_85

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Joined
Sep 29, 2003
Location
La Conner, WA
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... None :S
The low side is higher than the high side???

Sounds like the RCV is toast. If the compressor is actually turning, but not pumping anything, and the oil that came out looked good that's the only option.

Your car has no freeze switch on the evaporator, so if you defeat the RCV the evaporator will ice up. For a test I suppose it would be ok. But considering how inexpensive the compressors for these cars are I'd not bother.

-J
 

mustangmarty

Veteran Member
Joined
Nov 9, 2016
Location
Central Texas
TDI
1996 Passat Wagon TDI
Ok, I tried it with the m12x1.25 bolt and nut (m13 was too big) in place of the RCV. The AC finally started to cool a little bit. Not great, but at least something. But the fact that it cools somewhat with the bypass and not at all with the new RCV I installed leads me to believe that the new RCV in defective. Sound about right? Part number is EX10067c from UAC (Universal Ait Conditioning)
 

Mongler98

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Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
what is the PH of the oil? Drain the compressor and filter all the oil you can though a coffee filter. What it looks like to me is the compressor is not on, but you say that the clutch engages? at those low pressures? somethings not right. Highly suggest you get an OEM compressor, not some reman or some ebay junk.
 

Steve Addy

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Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Ok, I tried it with the m12x1.25 bolt and nut (m13 was too big) in place of the RCV. The AC finally started to cool a little bit. Not great, but at least something. But the fact that it cools somewhat with the bypass and not at all with the new RCV I installed leads me to believe that the new RCV in defective. Sound about right? Part number is EX10067c from UAC (Universal Ait Conditioning)
It would not be the first time replacement parts were bad out the door, unfortunately. At this point since you have it out it certainly wouldn't hurt to swap in another new one if you can get one in reasonably short amount of time.

Sorry to hear about your problems, here in Iowa we've been pummeled by heat for a few weeks now, AC is absolutely necessary IMO.

Stev
 
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