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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 July 25th, 2018, 14:32   #1831
dremd
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Quote:
Originally Posted by crashtested View Post
Why? It won't be working any harder then if the main cooling fan were running.

Completely false.

Higher temperatures cause high side pressure to spike, ideally the fan control module detects the high pressure and shuts off the compressor, but with one fan it will probably just make the compressor work 2x as hard.
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Old July 27th, 2018, 21:24   #1832
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Thanks to this thread being a Sticky, I discovered that the fans were both fried, before cooking the AC system, on the bargain beetle I just recently purchased. Saved me a pile of headaches! Replaced the fan assembly this afternoon (with a Chinese Ebay setup for $80). I guess I got what I paid for, as the RH condenser fan made it about 10 min before there was smoke coming out the hub....like the shaft is spinning inside the fan hub and melting the plastic. Yes, they both spun freely after install, and worked as they should in the test. Ebay seller is sending out a new (free replacement) set tomorrow, so hopefully it was just a freak happening.
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Itís not the fan that dies. The low speed resistor in the fan is too small. Vw designed it wrong and nobody ever put a larger resistor to handle it.
This one was not the resistor. The fan mount on the cheap Chinese fan set, was weak; which allowed the running fan to come into contact with the shroud. This effectively friction welded the fan to the shroud and the shaft spun in the hub of the fan.

I replaced the fan and shroud set with another set that the seller sent me at no charge. They made it until last week...when the resistors cooked.

Any chance anyone has used these? Might be a good option as the resistors are outside the motor housing and where they can receive airflow from the running fan....

https://www.amazon.com/Condenser-Rad...ords=1c0959455
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Old August 3rd, 2018, 18:42   #1833
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Heres one I need help with...

I keep burning up AC clutches. First I changed the clutch with loud bearing failure but everything worked.

Second clutch lasted about a week. One long drive and it was toast. Coil failed (due to heat I believe) and had infinite resistance.

This time I replaced the entire compressor with a new unit that had a new coil/clutch preinstalled. Filled 28g by weight all was well. Lowside low 30s, highside 200-230s if anyone is curious.

One long drive over an hour on a 90 degree day and it started blowing warm air. Got out and looked and the new clutch was slipping and had a ring of heat-discoloration. Caught it in time and after cooldown the clutch still engages but I am afraid to run it before fixing the root cause.

Do I need to replace the fcm or the high pressure sensor next? I tested the voltage without load and receive 9.6 at the plug going to the coil. Both radiator fans run fine and strong. Fuses are fine and not melted.

Observations are the ac doesnt cycle when parked but under heavier loads it feels like it cuts off and on but i thought that the ecu normally shut off the clutch under high loads (i.e. WOT). Seems like its not grabbing as hard as it could and longer drives are causing too much heat.

Any ideas? Was going to replace the FCM and high pressure sensor next.
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Old August 6th, 2018, 11:02   #1834
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Uh, did you check to see if the new compressor already had oil in it? The ones we install have full system charge already. Unless you flushed the system there was still oil remaining. 28g of oil or Freon? Normally takes 700g Freon on a MkIV.

First thought I had was to verify the air gap on the clutch. Then check the force required to turn the compressor. Also check the wiring to the clutch while you are there - if full current is not reaching the clutch then the coil can't pull tight enough and it slips.

WOW! 230PSI?! I'm seeing low 30s low side and 150-180 high side. Unless it has been running a while in 94F+ and high humidity weather. Even then I rarely see 200+ high side. BTW - I spent 7 years in Florida, never saw that unless something was broken/restricted.

Our cars don't cycle the compressor clutch. They are variable displacement and don't cycle unless pressure limit is reached or you turn AC off.

Sorry about the random burps of info,

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Old August 6th, 2018, 13:21   #1835
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I did fill the compressor with pag oil prior to install. I think I meant to say oz instead of g. We looked it up when i bought the freon and i did indeed refill this on a nearly 100 degree day that was rather humid. Pulled vacuum to purge before filling as is recommended.

I think the voltage is too low at the plug. But i need another weekend to get under and test it again. I wasn't hitting over pressure so I'm now thinking that the high-pressure AC sensor is indeed the cause of my cycling. That and the voltage means I probably have multiple issues going on.
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Old August 7th, 2018, 07:06   #1836
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So you filled compressor with PAG oil, but was there any oil already in the compressor when you bought it?

230 PSI is still a bit too high, IMHO.

Question on the high pressure sensor - is it not reading? Why do you think it's the cause of the cycling? If its a 3 wire sensor then it "talks" to FCM and it sends actual pressure, not just a switch that closes at a high or low limit. Most common failure is leaking out the sensor or just total failure which would mean no AC at all.

I think you may have a couple issues. A possible mechanical issue causing too high of pressure and electrical supply to clutch. But this is all Internet diag, so....

Jason
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Old August 7th, 2018, 20:31   #1837
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Originally Posted by Rinderle_77 View Post
This one was not the resistor. The fan mount on the cheap Chinese fan set, was weak; which allowed the running fan to come into contact with the shroud. This effectively friction welded the fan to the shroud and the shaft spun in the hub of the fan.
I replaced the fan and shroud set with another set that the seller sent me at no charge. They made it until last week...when the resistors cooked.
Any chance anyone has used these? Might be a good option as the resistors are outside the motor housing and where they can receive airflow from the running fan....
https://www.amazon.com/Condenser-Rad...ords=1c0959455
Update: I ordered these fans, they came in as a standard set of fans with enclosed resistors. Also, the small (passenger side) fan motor protrudes ~1.5" past the mount spider which will allow it to come into contact with the line off the back of the AC compressor.

Emailed the company with my concerns. They replied that the fans I was after are out of stock, and not sure when they'll be back in stock. Therefore, they have sent a return shipping label and will refund....

At this point, I wish I could just wire in a relay using the low speed power for trigger to send power to the high speed side of the fans and just run them on high speed any time the low speed is called for. I'm just not sure what that would back-feed on the high speed side of the FCM, etc.
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Old August 8th, 2018, 09:01   #1838
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Originally Posted by Rinderle_77 View Post
Update: I ordered these fans, they came in as a standard set of fans with enclosed resistors. Also, the small (passenger side) fan motor protrudes ~1.5" past the mount spider which will allow it to come into contact with the line off the back of the AC compressor.

Emailed the company with my concerns. They replied that the fans I was after are out of stock, and not sure when they'll be back in stock. Therefore, they have sent a return shipping label and will refund....

At this point, I wish I could just wire in a relay using the low speed power for trigger to send power to the high speed side of the fans and just run them on high speed any time the low speed is called for. I'm just not sure what that would back-feed on the high speed side of the FCM, etc.
Surprised you even got that far with Amazong, often they won't divulge 3rd party sources.
You should be able to rig the fans to operate that way, you'll need to "engineer" the new configuration to provide proper current where needed. Electrics are a bit more than just connecting wire, you may need a resister, capacitor or some such a thing. You may even need to change conductor size. Normally it's easier to just fix it as designed.
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Old August 8th, 2018, 21:40   #1839
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Surprised you even got that far with Amazong, often they won't divulge 3rd party sources.
You should be able to rig the fans to operate that way, you'll need to "engineer" the new configuration to provide proper current where needed. Electrics are a bit more than just connecting wire, you may need a resister, capacitor or some such a thing. You may even need to change conductor size. Normally it's easier to just fix it as designed.
Yeah, I was surprised to get this far... As far as wiring in the relay, I get by ok with most minor electrical repairs, but I'm like you in thinking that there would have to be a diode or two in there somewhere. I just hate the idea of tearing apart brand new fans to remove/relocate the resistors and effectively throw away what "warranty" they might have.....

Maybe Dan will chime in with yet another bit of wisdom. Like I said before, I know there has to be a way to make the fans only run on high as if the low speed wiring and resistors aren't even there.

And yes, I did look into the PWM controller from the fellows across the pond, you still have to have functional low speed fan motors (including the resistors) for the controller to work. It just manipulates the voltages and signal to alleviate stresses of constant load on the resistors.
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Old August 10th, 2018, 10:33   #1840
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Hi folks. 2012 Jetta issue.

I was having intermittent cooling fan operation, noticed by my a/c kicking on and off in city driving/red lights.

So i replaced the main large fan with new. seemed to work flawless for a day (probably coicidence) and im right back where i started.

I thought maybe i didnt connect the main electrical connector all the way so i jacked the car, pulled the lower cover off and right before i stuck my hand on the connector my fans randomly kicked on for the after-run function. I thought that was very odd.

Perhaps its the a/c pressure switch? as in the pressure had changed while it sat for 10 or so minutes while i was jacking the car and removing the cover?

any help would be greatly appreciated. I dont have a vag com and plan on getting some help later today but its not a guarantee i'll be able to do it.
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Old August 10th, 2018, 10:40   #1841
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Yea, Dan's been out since December. Hope he's O.K. I know he does take some long vacations.
I can tell you he's answered about every question imaginable on things AC. Do some advanced searching, include the term DanG144 and of course your issues.
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Old August 10th, 2018, 10:53   #1842
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There is just so much to go through, it would take me hours! I just really do not understand why this NEW damn fan isnt coming on, so its gotta be non-fan related. And on such a newer car.... i mean its 6 years old now. Frustrating since its not even paid off before its starting to go to ****. I expect this kind of crap on my 03....
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Old August 10th, 2018, 12:35   #1843
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Starting with Post#1, Dan covers fan diagnosis complete. Not sure what's different for 2012. But a quick read says adequate refrigerant pressure and proper signal from the high pressure sensor.
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There is just so much to go through, it would take me hours...........................
You can trim that down to minutes using advanced search. Must be frustrating on such a new car!
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Old August 10th, 2018, 17:40   #1844
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So I found my new fan must not have seated in the main plug all the way. I got a nice little burn spot around the pin for the ground. In fact the new mk6 plug is a terrible design. After a few years in the heat it won't hold together at all any more. It's just held together by friction. Tab is in tact but barely has a grab. Will zip tie.

Hope it was just burning from being loose and not any other problem.

Also, my fan will go from low to high and back to low... But my ac will also only get to 60 degrees, and when the fan goes to low it will only go to 65 degrees. This is sitting in the driveway and it's currently 100 degrees outside. I feel like it should be blowing colder.
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Old August 10th, 2018, 18:04   #1845
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Can't figure out how to post pics from my phone and Photobucket doesn't work anymore but the connector is burning up at the large ground pin.

I'm at a loss of what to do next. I'm starting to hate this car. What a ****ty engineered plug.
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