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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 April 19th, 2009, 13:47   #46
cwarner
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the speed of the fans looks slow.. Oh and it's about 58 degree's outside. I don't know if that makes a difference.

If there is something wrong, where to I even start to trouble shoot ? I can here a solinoid /relay sound when they are starting/stopping. Could that be bad ? Both fans rotate easily by hand.
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Old April 19th, 2009, 17:01   #47
DanG144
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I really did not figure that it was very warm in Michigan, yet.

Take a look at the AC clutch. What is it doing? See if it is engaging when the fans turn on, or when they turn off, or not at all. Look at the center of the AC compressor pulley, it is engaged when the center (and thus compressor) turns with the outside of the pulley. This may help us figure out what is going on.

I would start with the link in Post #1 that says
A4 fan troubleshooting

And depending upon what I find out go to this document,

Fan Repair

or whichever document below applies to your year car.


Sept 98 - May 99 Build date A4 Manual Air Conditioner Troubleshooting

May 99 - end of A4 Manual Air conditioner Troubleshooting

Last edited by DanG144; April 19th, 2009 at 17:04.
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Old April 19th, 2009, 17:06   #48
cwarner
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Quote:
Originally Posted by DanG144
I really did not figure that it was very warm in Michigan, yet.

Take a look at the AC clutch. What is it doing? See if it is engaging when the fans turn on, or when they turn off, or not at all. Look at the center of the AC compressor pulley, it is engaged when the center (and thus compressor) turns with the outside of the pulley. This may help us figure out what is going on.

I would start with the link in Post #1 that says
A4 fan troubleshooting

And depending upon what I find out go to this document,

Fan Repair

or whichever document below applies to your year car.


Sept 98 - May 99 Build date A4 Manual Air Conditioner Troubleshooting

May 99 - end of A4 Manual Air conditioner Troubleshooting
Cool,
Thanks for the links. Looks like I've got some work to do.
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Old April 19th, 2009, 18:02   #49
DanG144
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I tried to upload a new rev of the AC troubleshooting PDF, and something is not working. It ruined the old document, and did not replace it.

I am not sure what is wrong. I have done this before, so I suspect I know how. The site just does not seem to be working. It is past my bedtime now, so I am signing off.

If anyone needs the May 99 and later A4 AC troubleshooting guide, send me a PM with an email address, and I will send you the document.

Dan
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Old April 20th, 2009, 10:08   #50
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Here is a new link to troubleshooting A4 air conditioners for cars built after May 99.

http://pics.tdiclub.com/data/517/A4_...ing_Rev_41.pdf
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Old April 22nd, 2009, 18:35   #51
Jarmstrong
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Am i correct in understanding that these fans only run when the AC is on? so if i only have one working at idle, i can not use the AC until I find the time to fix it?
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Old April 22nd, 2009, 18:52   #52
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The fans will run from radiator thermoswitch signals, from AC signals, and from ECU signals.

If only one fan is running from your AC signal, then it is likely only one fan will run from all of your slow speed signals. You may have two fast speed fans running, when you get a FAST speed requested, or you may not.

Your AC will work a bit harder, at higher temperatures and pressures with only one fan running. The AC compressor will age a little faster, but it will cause no short term problems.
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Old April 28th, 2009, 09:57   #53
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Dan-thanks for all the pdf's-and the fact that they contain pictures-they always help a LOT!!!

The AC on my A4 is working fine-at the moment-but the AC on BOTH of my B4's is not. One may just need a recharge-but the other one I have already tried that.

I realize the AC systems are probably different on the A4 versus B4-but I assume a lot of the troubleshooting/basic concepts would be similar-correct???

In my experience there are a quite a few people that know quite a lot about TDI's........but even a lot of the "TDI gurus" often know very little about the AC........and usually if you take a non-working AC to a local AC place or a dealer for that matter the bill will be HUGE........and I'd suspect that often that is because they "replace parts"-instead of just getting it to work/really troubleshooting the problem.........

So this is especially needed-and yeah this should definitely be a "sticky" or put in the "how-to" area permanently-thanks again!!!
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Old May 1st, 2009, 07:09   #54
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any idea what the resitance should be on the plug for the driver side fan?

how about for the wires on either side of the resistor inside the fan motor.

thanks
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Old May 1st, 2009, 07:29   #55
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Look at the photos and captions near the end of the fan troubleshooting guide in post #1 of this thread. It covers the fan resistances.

Here is a copy of a photo caption:
"This is a shot of the drivers side fan connector. Note the spade connections. In this shot pin 1 is bottom, pin 2 middle, pin 3 top. These are 1/4" spades. The resistance on my good fan was 1-3 0.6 ohms, 1-2 0.8 ohms, 2-3 1.2 ohms."

You will have to be more specific on what you are asking for about the resistances on the internals. (And I would have to go and measure one.) The important internal resistances should be the same as those measured from the plug. You are essentially measuring:
pins 1-2 across the resistor.
pins 1-3 across the fan winding.
pins 2-3 across both the fan winding and resistor in series. (I know they do not quite add up, but that is life; not perfect but good enough.)


The resistances across the brushes should be on the order of 0.1 or 0.2 ohms.

Does that help?


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Old May 1st, 2009, 14:35   #56
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thank you. my resistances read alot more than that but it works so i'll call it good. and i couldn't even get a good reading from one end of the resistor to the other.

thanks
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Old May 6th, 2009, 17:40   #57
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I am having an issue with my A/C were it works first thing in the morning, but when the car has been sitting outside all day in the sun (I live in Florida, so the outside temp is between 88F to 100F deg) the A/C will not come on for about 10 minutes or so. I did some investigating. Both fans come on just as described in the above posting. I noticed that the compressor was not running. After about 10 minutes sure enough the compressor started and the A/C was working. I went out and bought a Freon re-charge kit to see if the Freon was low. It was not the case. The pressure measured around 48 PSI on the low side. According to the directions on the side of the Freon can the PSI should be between 45 and 55 PSI when the ambient temperature is around 95F.
I am not sure why the compressor is not turning on right away and waiting 10 minutes before turning on. It only seems to happen when the car has been sitting out in the sun for long periods of time. Any help would be greatly appreciated.

Thanks,
Daryl

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Last edited by dmorrell; May 6th, 2009 at 17:43.
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Old May 7th, 2009, 02:46   #58
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Freon?

Our air conditioners should not be using Freon, but R134A, and I am pretty sure the pressure should be about 110 psi for 95F. This is in equilibrium, if it is 95 out, but the refrigerant is boiling out of your can, then the pressure would drop, and the can cool off.

some people have published that some pressure gauge fittings will not open the schrader valve on the A4 VW - that they can be problematic.

The low pressure cutout should actuate at about 14.5 psig, and reset about 70 psig (as sensed on the high pressure side of our systems). So even with 45 psig you would be above the low pressure cut off.

All that being said, it sounds as if the most likely problem is a faulty ambient temperature sensor. This is located in the plenum under the windshield for most A4 cars with manual AC, on the left side. I do not have a tech manual, or any experience with the A5 cars, or for climatronic AC.

Do you have climatronic AC?

The only way to tell for sure what is going on is to do some troubleshooting. The A4 troubleshooting would probably work fairly well if you have manual AC, but not if you have climatronic.

Let me know what type of AC you have. I may be able to look into it.
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Old May 7th, 2009, 03:09   #59
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Thanks for the correction, It would be R134A and not Freon. I assumed that R134A was just another form of Freon.

I do have the climatronic AC.

The system was reading about 100PSI (that was about as high as the gauge would go) with the compressor off and 48 PSI with the compressor on.
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Last edited by dmorrell; May 7th, 2009 at 03:13.
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Old May 7th, 2009, 05:04   #60
DanG144
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Thanks for the update. That all sounds normal.

If you can get someone with a CAN bus VCDS, the diagnostics and trouble codes for a Climatronic read pretty good. (I have never done it, just read about it.) So a VCDS inspection may show what is holding out your clutch.

Dan
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