Mk4 bew fans not working

Jay508

Member
Joined
Jun 5, 2021
Location
Mass
TDI
MK4 Golf BEW
Hey guys i am new to the group here. So i just purchased my first TDI it is a 04 mk4 golf BEW engine i beleive. So i have been trying to get my AC to work. I was told to check my radiator fans and see if they kick on with thw ac button on and fan on low speed. I tried this and they do not come on. So i changed the FCM, checked the 30amp fuses on top of battery, check the fuses on the side of the dash and they were all good and fans still dont kick on. So yesterday i bought new radiator fans from advanced auto and just plugged them in and still nothing. What else is there to check? Thanks in advance!

-Jay
 

drucifer

Veteran Member
Joined
Dec 21, 2013
Location
fredericksburg virginia
TDI
2004 jetta sw tdi pd
Oops


From what you said, maybe you don't have power at the plug to the fan module.
 

Lex4TDI4Life

Top Post Dawg
Joined
Jun 22, 2006
Location
NorCal
TDI
2001 Golf-Ute TDI GLS 5spd Manual
Check the fuse block on top of the battery. Your fuse (and everything else) could be fine. To expand, I was having the same problem on my ALH. I bought a new fuse block and everything was fixed. A cheaper solution would be to pull the connections from your fuse block and wire an inline fuse in, bypassing the block entirely.
 

Jay508

Member
Joined
Jun 5, 2021
Location
Mass
TDI
MK4 Golf BEW
So today both fans kicked when i hit the ac button. But no cold air? Also i came back a little later and the fans wouldnt come on again....... any thoughts?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
I’m not 100% sure but if there is not enough pressure in the system then the fans along with the A/C won’t come on.

1. Id at least check to see if you have enough pressure in the system.
2. Check for voltage across the fuse on the fuse block , make sure you have 12v on both side of fuse.
3. With a/c switch on check for 12 volts at the compressor.

You could also have a faulty a/c switch on your panel. Lust trying to give you some places to look.
 

pedroYUL

Veteran Member
Joined
Sep 8, 2011
Location
MI, USA
TDI
2015 Passat CVCA; 2015 GSW CRUA; 2012 wagon CJAA; 2004 wagon BEW
Fans should come on full blast, if I remember the troubleshooting guide correctly, when the AC button is on, AND the speed set to max. Also, temp needs to be above X, a wrong temp reading can confuse the system.

If your resistor pack is bad, and won't set the system to max, the fans up front won't necessarily come on.

Read the whole troubleshooting guide that DanG144 put out, it is very detailed.
 

P2B

Top Post Dawg
Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
Fans should come on full blast, if I remember the troubleshooting guide correctly, when the AC button is on, AND the speed set to max. Also, temp needs to be above X, a wrong temp reading can confuse the system.
Nope. Fans should come on low when the ignition and AC button are on. Speed setting and temperature are irrelevant.
If your resistor pack is bad, and won't set the system to max, the fans up front won't necessarily come on.
Radiator fan operation does not depend on blower motor setting.

Read the whole troubleshooting guide that DanG144 put out, it is very detailed.
This
 

Jay508

Member
Joined
Jun 5, 2021
Location
Mass
TDI
MK4 Golf BEW
Thank you
I’m not 100% sure but if there is not enough pressure in the system then the fans along with the A/C won’t come on.

1. Id at least check to see if you have enough pressure in the system.
2. Check for voltage across the fuse on the fuse block , make sure you have 12v on both side of fuse.
3. With a/c switch on check for 12 volts at the compressor.

You could also have a faulty a/c switch on your panel. Lust trying to give you some places to look.

Thank you! So the other day i got the fans to work by re plugging all the plugs and making sure they were tight. But now the compressor isnt kicking on. I went to a shop and got it charged. So i know it has pressure now. Anything else i should look into?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
You need to see if you have 12 volts at the compressor connector with the switch on , and engine running and fan speed to at least 1.
If you do have voltage there then switch your volt meter to ohms and check the resistance on the coil. It should read maybe 3 to 5 ohms......if it reads open then you have a bad coil and that will prevent it from coming on if bad.
That can be changed separately, you don’t have to remove the compressor and dump the system.

( edited for engine needed to be running.....brain fart and had wrong ohm range)
 
Last edited:

Jay508

Member
Joined
Jun 5, 2021
Location
Mass
TDI
MK4 Golf BEW
You need to see if you have 12 volts at the compressor connector with the switch on , key on but engine not running and fan speed to at least 1.
If you do have voltage there then switch your volt meter to ohms and check the resistance on the coil. It should read maybe 20 to 50 ohms......if it reads open then you have a bad coil and that will prevent it from coming on if bad.
That can be changed separately, you don’t have to remove the compressor and dump the system.
Thank you steve! I am going to try thing tomorow at work! I will reply back here!
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
So much wrong/bad misinformation in this thread, and so much needless shotgunning of parts at this poor car.

DanG144's thread is VERY good, and correct. Use that. Go step by step if you have to.

I will throw you a bone (or several):

Aftermarket cooling fan motors are short lived junk.

Aftermarket fan control modules are short lived junk, and what's worse, lots of times they have some aspect of them inoperable right out of the box.

If you turn the key ON, and press the A/C button, so long as the blower speed setting is not OFF, both of the cooling fans should come on low speed.

You can watch A/C request in the engine data.

The clutch will NEVER get power unless the engine is running. The FCM outputs a brief flash of 12v to engage the clutch, then backs off to around 7-8v. This is known as current ramping. It takes more "juice" to pull the clutch in initially than it does to hold it there. So if you just check that with a test light, or a cheap meter, you may not see anything at all, or just a quick flash.
 

Jay508

Member
Joined
Jun 5, 2021
Location
Mass
TDI
MK4 Golf BEW
Ok so i checked the compressor plug and i have 0 volts going to it. I followed the wire and saw that green wire #3 was broken. So i took battery out and box and found the green wire and cut it back and re wired the green wire. Compressor still doesnt kick on. And now my car has randomly died on me twice while idling?
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
Ok so i checked the compressor plug and i have 0 volts going to it. I followed the wire and saw that green wire #3 was broken. So i took battery out and box and found the green wire and cut it back and re wired the green wire. Compressor still doesnt kick on. And now my car has randomly died on me twice while idling?
Read the AC doc Oilhammer referred you to The link is in comment #3 posted by drucifer. Go step by step, even if you have partially done some of that during this whole episode. You need to be methodical and that way we can help you better knowing what you have eliminated as the problem.

At the end of the first post he has links to updated information too.
 

pedroYUL

Veteran Member
Joined
Sep 8, 2011
Location
MI, USA
TDI
2015 Passat CVCA; 2015 GSW CRUA; 2012 wagon CJAA; 2004 wagon BEW
But randomly dying... I'll say search the term coolant migration, check/clean common grounds (a typical problem one is below the battery tray)...actually, most likely you disturbed that ground connection.
 

Jay508

Member
Joined
Jun 5, 2021
Location
Mass
TDI
MK4 Golf BEW
So when i check the compressor plug for power should it be running? I tested it with ignition on, ac on and blower fan speed on 1. And then should i test the plug on ac compressor for ohm? Sorry i a new to trouble shoot electrical issues. Reallly appreciate everyones input! Thank god for tdi club! Lol
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Yes car needs to be running with ac switched to on and fan switched to 1 or higher, you should have 12 volts on the connector.
If you do have that shut car off and switch your meter to ohms reading and check the coil on the compressor....if coil is good you should have about 3-5 ohms of resistance......if it’s open then coil is bad.
 

Zak99b5

Veteran Member
Joined
Apr 30, 2021
Location
Albany NY
TDI
2003 Jetta TDI
With the car off, you’ll read ~9vdc at the compressor connector, but it’s a low amp “phantom” voltage from the fcm.

Leave the compressor plugged in, and use pins to probe the wires with motor running. When a/c and inside fan is turned on, then you should see the 12v.

Did you ohm out the compressor coil? Or give it straight 12vdc to see if you hear the clutch click?
 
Top