Check your radiator/condenser fan operation NOW

DanG144

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Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
If your AC system refrigerant pressure is too low the Fan Control Module will prevent the clutch from engaging AND the fans from turning on.

The pressure setpoints are located in a table in one of the PDF links in post #1 on troubleshooting AC.
 

Yardstick

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Chandler, AZ
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2003 Jetta TDI
So, provided the A/C is charged, the compressor clutch will engage with the engine off but the ignition on, A/C button on and fan on low? That seems a bit odd.
 

DanG144

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Chapin, South Carolina, USA
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Actually I am not sure if the clutch will engage with the engine off. I never had a reason to check.

What I do know is that low refrigerant pressure will prevent the fans from running and the clutch engaging - with the key on OR with the key off.
 

iamstuffed

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Jan 30, 2005
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San Francisco, CA
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2005 Golf GLS TDI Blue Anthracite
My driver's side fan isn't operating. Good thing I checked before the start of the super hot summer! At least now I have something planned for the weekend.:)

Thanks for the info.
 

iamstuffed

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San Francisco, CA
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2005 Golf GLS TDI Blue Anthracite
Yesterday I repaired the fan. One of the brush holders was melted slightly, and the brush was not moving at all. After scraping some of the plastic away, I got it to move, although not as well as the other side.

So far, the fan seems to be working fine. I ordered a new one and will be replacing this one with the new one when it arrives.

People should definitely try this repair before buying a new one. In my case, I'm just worried that the plastic will prevent the brush from moving freely after some dirt is reintroduced.

Thanks.
 

jun_1.8T

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May 31, 2009
Location
GTA, Ontario
TDI
Jetta
hey guys im new here. good thing i've found this thread because i was searching for some answers regarding with my problem.

here is my problem....

1. first start in the morning around 5-10 mins into the drive with my a/c on the bigger fan turns on low speed only. i turn off the a/c the fan shuts off. when driving only the bigger fan comes on. never saw the smaller fan come on whenever i turn on the a/c.

2. sitting on idle for more than 5 mins with my a/c on the bigger fan stops working and the compressor disengages and i lose a/c. if i sit on idle for more than 10 mins...i will see that my temp slowly creeps up and neither my a/c nor any of the fans work.

3. i drive off then the temp goes back to normal then the a/c starts to blow cold again. the bigger fan starts to come on again. i only get the fan to come on whenever i turn the a/c on. if i drive without a/c at night no fan will turn on. i sit on idle then my car starts to overheat. so what i'll do is to drive off to get the temp back down and turn the a/c on for the fan to come on.

4. this was doing this last fall already but didnt really bother with it as it got too cold up here really fast and i never had the problem with overheating. i actually saw the smaller fan come on last fall intermittently....probably a couple of times


.....so what could be the problem be. i really hope that i could figure this out on my own as my local shop is charging me a fortune for this with no guarantees. i've replaced the t-stat 2 months ago. does the green top coolant sensor play a role too in this??? should both fans come on as soon as i turn on the a/c??? hope you guys could help with this.

thanks!
 

iamstuffed

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2005 Golf GLS TDI Blue Anthracite
jun_1.8T said:
hey guys im new here. good thing i've found this thread because i was searching for some answers regarding with my problem.

here is my problem....

1. first start in the morning around 5-10 mins into the drive with my a/c on the bigger fan turns on low speed only. i turn off the a/c the fan shuts off. when driving only the bigger fan comes on. never saw the smaller fan come on whenever i turn on the a/c.

2. sitting on idle for more than 5 mins with my a/c on the bigger fan stops working and the compressor disengages and i lose a/c. if i sit on idle for more than 10 mins...i will see that my temp slowly creeps up and neither my a/c nor any of the fans work.

3. i drive off then the temp goes back to normal then the a/c starts to blow cold again. the bigger fan starts to come on again. i only get the fan to come on whenever i turn the a/c on. if i drive without a/c at night no fan will turn on. i sit on idle then my car starts to overheat. so what i'll do is to drive off to get the temp back down and turn the a/c on for the fan to come on.

4. this was doing this last fall already but didnt really bother with it as it got too cold up here really fast and i never had the problem with overheating. i actually saw the smaller fan come on last fall intermittently....probably a couple of times


.....so what could be the problem be. i really hope that i could figure this out on my own as my local shop is charging me a fortune for this with no guarantees. i've replaced the t-stat 2 months ago. does the green top coolant sensor play a role too in this??? should both fans come on as soon as i turn on the a/c??? hope you guys could help with this.

thanks!
I think you need to read this thread in its entirety, and read BOTH the fan repair and the testing procedure pdfs
http://pics.tdiclub.com/data/517/A4_Coolant_Fan_testing_Rev_5.pdf
http://pics.tdiclub.com/data/517/Fan_Repair.pdf

Both fans should operate at the same time.
 

DanG144

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Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
jun,
I agree with iamstuffed.

It sounds as if you need to repair or replace BOTH of your radiator/condenser fans.

Going through the troubleshooting PDF's would nail it down, and there is about an 80% chance that the fan repair pdf would fix them and let them run for another year or two.

If the fans will not spin easily by hand, then just replace them.

Dan
 

visionlogic

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Aug 23, 2006
Location
Daphne, AL, USA
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2002 Jetta TDI
Well, my large fan (driver's side) would not run with the A/C button activated, blower on, and ignition on. Disconnected the fan harness connector and tested the fan directly with jumpers to battery. Still no run. So, pulled the fan, dremeled off the back plate, and as luck would have it both brushes are solidly stuck in their melted plastic holders. Time to order a new fan. Thanks for this excellent troubleshooting info.
 

jun_1.8T

Member
Joined
May 31, 2009
Location
GTA, Ontario
TDI
Jetta
thanks guys for those two helpful links.

a couple of questions i have. is the thermo switch same as the radiator fan temperature switch??? and then what would be the easiest way to unplug the plug for the thermo switch??? i wanted to try to test the thermoswitch first before i go any further.

thanks guys for all the help!
 

DanG144

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Location
Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
Yes, the switches you mention are different names for the same switch.

You unplug it like most VW electrical plugs.

You press the outer end of the rectangular protruberance. It is actually a lever that pivots and lifts the far end when you press the outer end.

Lifting that lever moves a catch up and clear. You cannot see any of this happen.

Also like most VW electrical clips, it can be a royal pain. They are often very hard to take off when they have been in place for years. They stick.

Try squeezing the two large sections together, then pressing the lever and trying to pull them apart. Try several times.

You might learn on an easier to get to electrical connector, such as the one on your coolant reservoir. It works the same way, it is just a smaller example.

If you finally resort to a screwdriver to pry on the connector you have a 50% chance of breaking off the clip, in my experience. So try a dozen times without any pry tools.

Even if you break the clip off, it is not the end of the world. MOST of the time friction alone is enough to keep the clips engaged.

Dan
 

Yardstick

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Chandler, AZ
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2003 Jetta TDI
Mine turned out to be something a bit different. Neither of my fans were running. The middle bladed fuse in the fuse block on top of the battery didn't blow, but the side closest to the driver melted! I think corrosion (and demand) caused heat buildup and it overheated on that side. I'm surprised it didn't blow the fuse though. At first just cleaning the contacts worked, but I ended up buying a new fuse block (~$130 at the dealer -Ouch!). After that both fans worked and the A/C came back on, nice and cold!
 

DanG144

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Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
Yardstick,
Thanks for pointing this out. It is actually very common.

I thought I had it covered, and I did. But not in the fan troubleshooting pdf, but the AC troubleshooting pdf.

I will add the photo and notes to the fan troubleshooting pdf.

I hesitate to tell you this, (after your OUCH) but you can often unbolt all the connections on that housing, then split the casing open, and clean up the overheated contact. With an emory board.

Once cleaned up, it works again like new.
 

Yardstick

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Location
Chandler, AZ
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2003 Jetta TDI
Good tip. I went for the new one because it seemed enough different from the old one that I figured it might have been improved. Maybe not, but now hopefully the new owner won't experience the same problem. (Sold the car Monday)

Edit: Here's a picture of the melted spot...
 
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VegBug

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'98 New Beetle

DanG144

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Chapin, South Carolina, USA
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You might split that fuse box and clean up the contacts. Replace if you cannot restore good (read low temperature) contact.

What makes you think the refrigerant pressure is ok? Actual measurements?

Dan
 

VegBug

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Indianapolis
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'98 New Beetle
Saw that and figured would give me a better idea. I'll see if there are any fellow TDI'ers locally that might have one I can use.

thanks

Jerry
 

DanG144

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Joined
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Location
Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
Even a good high and low pressure gauge set is still just part of the story on refrigerant charge.

You need to be sure the proper amount (weight or mass) of refrigerant and oil is in the system.

If you have too much charge, then the high pressure side pressure can be too high, and the G65 turns off the compressor, but lets the fans run. This happens when the high pressure side is essentially full of liquid- no gas space left.

If you have normal pressures that just means there is some liquid refrigerant present. There may not be enough for the system to work properly, or there may be too much.

And then you cannot assume the G65 pressure sending unit is reporting properly. You have to verify that it is sending the proper signal for the pressure that is present.
 

VegBug

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AH! Which brings me to my next question, after reviewing the WONDERFUL & FANTASTIC write up have!
I'm basically trying to follow your steps for troubleshooting and happened to stop at the fuse issue. I do have a question concerning the testing of the G65, I see the safety pin through the white wire but where does the black lead, of the meter, get connected to? Based on your image of the wire harness there seemed to be more than two wires in there but I haven't had a chance to look at mine to see if there were more than two wires.
thanks
Jerry
 
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DanG144

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2005 A4 Jetta 5spd
If two measuring points are not specified, put the common meter lead on a good ground. The battery negative terminal, or a good clean metal bit that has a path through metal back to the negative battery terminal.

Dan
 

jun_1.8T

Member
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May 31, 2009
Location
GTA, Ontario
TDI
Jetta
Hi Dan,

ok...after 2 days of trying to pull the harness from the thermoswitch i've finally was able to. i did the test and nothing came on for both the low speed and high speed tests:( . checked all my fuses in the battery box and they were all good. checked pin 2 on the wire harness for voltage and it was dead....as in no voltage at all. i used my multi meter to check for this. looked closely at fuse#8 as you mentioned and from what i can see everything looks good. so what could be wrong here???

so i just want to clarify some things to be sure. fuse#8 is the last fuse on the right when looking at the battery from the front of the car right? also could i run a wire straight from the battery to pin#1&3 on the wire harness so i can do the test for the low/high speed of the fans?? wont i mess up anything???

im very puzzled here as everything looks good on the battery tray but yet i dont have power on the wire harness. what is the wiring schematics for that harness for the thermoswitch? does it run straight from the battery box to the harness or does it go somewhere else?

thanks for all your help guys....hope that i could get to the bottom of this.
 

DanG144

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Confusingly enough fuse 8 is the green fuse closest to the metal fuses. Open up the Rev 6 A4 troubleshooting pdf in post #1 and you will find a labeled photo.

Quite often the fuse is fine, but the connections below it are bad. That is the first place I would look. Any signs of corrosion or heat, or both? If you unbolt all the connections on this fuse box you can split it open and clean it.

You could put a jumper on Pin 2 of the thermoswitch, but the wiring is very direct, only one splice between the fuse and the thermoswitch. If you did run a jumper to pin 2 you could check your fans on slow speed, but you need power on the wiring harness itself for fast speed.
 

jun_1.8T

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Location
GTA, Ontario
TDI
Jetta
thanks dan...

i didn't know that the fuse box can split into two. so after unbloting all those connections i can actually take it apart...will come apart easily???

and just to make sure....i could just run a fused jumper wire from the positive side of my battery and jump pin#1 on thermo switch?? i want to do this because i want to make sure first that my fans really do work.

anyways...thanks a lot for the help and i'll keep you posted.
 

DanG144

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I think it will split fairly easily. No personal knowledge, a report from someone else.

To test both slow speed fans at once, just jump fused power directly to pin 1 of the thermoswitch connector. This is a definitive test of slow speed operation.

You can try to jump fused power directly to pin 3 as well, to see if the fast speed fans will work, but I have little hope that they will, due to no power being fed to the fan control module. This is not a definitive test.

If you jump fused power to pin 2 of the thermoswitch it should backfeed to the fan control module. Then put power on pin 3 and see if the fans will run in fast speed. This should be a valid test.

But if I want to know the conditions of the fans, I take the individual fan connectors apart and put power directly to the fans. Ground pin 3 of the fan connector, put fused power to pin 1 for fast speed, then take that off and put fused power to pin 2 to test slow speed.
 
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