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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW MKIV-A4 TDIs (VE and PD)

VW MKIV-A4 TDIs (VE and PD) This is a general discussion about A4/MkIV Jetta (99.5-~2005), Golf(99.5-2006), and New Beetle(98-2006). Both VE and PD engines are covered here.

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Old March 22nd, 2009, 18:59   #1
DanG144
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Default Mk IV Manual AC electrical & cooling fan troubleshooting and repair

Now is the time of the year to check that your pair of electric fans that provide cooling for both the radiator and air conditioner condensor are functioning. Do not needlessly age your Air Conditioning compressor by running it at too high a pressure and temperature.
(Now being spring, with temperatures above 35 F. There are interlocks that prevent operation below freezing.)
A4's and A5's (I suspect others, too) have bad problems with radiator/condensor coolant fans not being operational.
There is no DTC or MIL light that comes on for this. No overt warning at all.
Most people do not notice anything until both of their fans have quit completely, and then they might notice that the AC compressor kicks off when at stop lights or in traffic. They may notice their AC is not as cool as normal. This is the terminal stage of this disease.
Here is the usual progression of this failure.
1)One fan slow speed operation fails, no one notices. The AC is operating at higher than normal temps and pressures, but still does a good job.
2) The second fan's slow speed operating mode quits; no one notices. The AC compressor is running even hotter and at higher pressures. When the vehicle is not moving, the pressure builds up to the high pressure point on the refrigerant pressure sensor. The high speed fans kick on, and the compressor kicks off; this lasts about 20 seconds, then the compressor kicks on and the fans kick off (they should be in slow, but that has failed. The cycle repeats about once per minute. Most people will still not notice this, as the refrigerant pressure stays high and they get some cooling.
3) The repeated cycling of the high speed fans, and their very high starting current will eventually cause some electrical connection or component to fail in the fan circuit. All fan operation is lost. This folks usually notice when they are at stop lights or in traffic, as the AC compressor will kick off and on repeatedly. Cabin cooling is usually affected, and many notice, but some think it is normal operation.
To avoid this scenario check your fan operation every time you check under the hood (every refueling, right?)
Manual AC (as opposed to Climatronic AC or Climatic AC -the transmission type is immaterial) cars, push the AC button in, place a fan in slow and leave your key to ON (engine does not have to be running). Both fans should run in slow (unless it is near freezing or your refrigerant pressure is too low.) If your AC light does not come on and your cabin fan does not work, do not proceed until you have troubleshot and fixed this problem; this is the primary signal to turn on the AC system.
Climatronic or Climatic AC cars (includes all A5 cars), with the engine running, select low cabin temperatures for climatronic or AC on fan on for Climatic, make sure you are not in ECON mode, and check your fans. Both should be running at a slow speed condition within about 30 seconds (they are infinitely variable in speed.) Again this is dependent upon not being in near freezing conditions and having adequate refrigerant pressure. Your fans key off of refrigerant pressure signals, so the compressor must be good and be loaded in order for the fans to see a high enough pressure to start.
During the engine output tests with VCDS, if there is a fan test (and there is on BEWs and BRMS) then BOTH fans should run together.
AC troubleshooting:Folks, a reminder. This thread is for solving electrical control problems in the Mk IV Air conditioning systems. If your clutch is engaging, and your fans are running, then you will not find your answer in this thread.
If your clutch is engaging and your fans are running, check out the Refrigerant Control Valve threads and the lost-foam-on-the-temperature-control dampers or flaps or doors threads. If your pressures are normal, look at the flapper doors, if the differential pressure is lower than it should be, then look at the RCV threads.
Some links to PDF papers on troubleshooting A4 fans and Manual Air conditioners. Please forward any questions or corrections to me (DanG144).
A4 fan troubleshooting
Sept 98 - May 99 Build date A4 Manual Air Conditioner Troubleshooting
Rev 7 May 99-end of A4 Manual Air Conditioner Troubleshooting.
Fan Repair
pinout of J293 Thanks to wulee
Refrigerant Pressure table vs temperature and G65 pressure transducer This is based solely on reading one (my own) pressure transducer; this is not guaranteed accurate. If you have the real calibration data, or data from your own transducer, please forward it to me.
A very kind anonymous user has generated a set of schematics for the MK IV (May99 to MY2005.) The first is one piece for easy viewing, the second is two pieces for easy printing. Thank you Anonymous.
http://pics.tdiclub.com/showphoto.ph...ematic&cat=517

http://pics.tdiclub.com/showphoto.ph...-mk-iv&cat=517

Last edited by DanG144; August 20th, 2016 at 16:51. Reason: added links to pdfs for fan and AC troubleshooting
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Old March 22nd, 2009, 18:59   #2
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reserved.
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Old March 22nd, 2009, 19:16   #3
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Quote:
Originally Posted by DanG144
Manual AC cars, push the AC button in, place a fan in slow and leave your key to ON (engine does not have to be running). Both fans should run in slow (unless it is near freezing.)

Climatronic AC cars, with the engine running, select low cabin temperatures, make sure you are not in ECON mode, and check your fans. Both should be running at a slow speed condition within about 30 seconds (they are infinitely variable in speed.) Again this is dependent upon not being in near freezing conditions.
This is a good advice! Thanks Dan! I just ran out the garage and tested both fans run without starting the engine. Just pushed the AC button and set the fan speed to the lowest setting and checked under the hood.

Also found out where the 5 to 10 second SCREECH that I heard the other day when my wife started the car came from. I am happy to say that I am sure that it did not come from one of the belt tensioners now! I heard the exact same screech this time when the fans started but it only lasted .5 seconds. I will keep my eye on this. Thanks again! Very cool that this can be tested with engine off. Very timely also.
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Old March 22nd, 2009, 21:39   #4
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I wish that I had the opportunity to use my AC. It was -5 and snowing all day here. But when it does finally warm up, I'll definitely check it. I think that I might have this problem, because last summer it sometimes took quite a while for it to blow cool air. Then again, I rarely use my AC and I'm perfectly happy rolling down the highway or in town with the windows down. I'll still look into it though, I like it when things work and my dad loves the AC.
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Old March 23rd, 2009, 06:28   #5
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guess Ill be checking this later today.

Thanks!
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Old March 23rd, 2009, 14:26   #6
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Checked. Both fans ran, one screeched very briefly but I couldn't get forward quickly enough to determine which.
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Old March 23rd, 2009, 15:10   #7
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Checked mine on my 2001 Golf GL.

key on, fan on low, AC button pressed.


2 fans running. Thanks for the heads up.
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Old March 23rd, 2009, 16:56   #8
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Last November, at the Georgia GTG, of the first 6 cars I checked, NONE of them had two good fans.
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Old March 24th, 2009, 18:48   #9
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Default Bad Fan?

I checked my AC fans today and saw that (1) was running. the passenger side worked but the drivers side was not working.

Should they both run with the test that is for the M/T A4?
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Old March 24th, 2009, 19:01   #10
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Yes, both fans should run together, every time, in every A4 or A5.

While it could be a bad controller, it is very likely the fan itself.

Dan
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Old March 24th, 2009, 23:38   #11
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So I just went out and tested my fans and suprisingly they both work. The reason I'm suprised is because I have all the symptoms of the a/c cutting out all the time. I've been trying to figure this issue out since I bought the car. If there is anyone in this thread that can point me in the right direction that would be great.
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Old March 25th, 2009, 01:17   #12
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Those of you with an A3 or B4 should also check your fan belt... yes, there is an eeeney weeney little belt connecting the two fanwheels. I've yet to see one broken, but I've seen many that were looking sad enough to need replacement. PN 1H0119137A for Jettas and 3A0119137C for Passats.

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Old March 25th, 2009, 05:05   #13
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Quote:
Originally Posted by egibbys
So I just went out and tested my fans and suprisingly they both work. The reason I'm suprised is because I have all the symptoms of the a/c cutting out all the time. I've been trying to figure this issue out since I bought the car. If there is anyone in this thread that can point me in the right direction that would be great.
The first thing I would do would be to check the AC pressures. Yours is old enough to have lost some of its charge. If they are good, then it could beyour high/low pressure switch, your ambient temperature interlock temperature switch, your wiring or your clutch coil going bad. I listed them in the order I would suspect them.

The link below will lead to a PDF with some technical info in it that will help troubleshooting.

A4 1999.5 air conditioner check
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Old March 25th, 2009, 05:48   #14
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Should this become a sticky?
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Old March 25th, 2009, 11:28   #15
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Checked mine and surprisingly they still work on a 6 yr old car. The passenger fan is squeaking pretty good though. Anyone have any suggestions on what to do about that? Should I attempt to lubricate it?

Thanks,
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