Check your radiator/condenser fan operation NOW

DudaEnergy

Well-known member
Joined
May 4, 2015
Location
Madison, AL
TDI
2003 VW 1.9L
No.​
Designation in Wiring Diagram
Nominal Value​
Function/Component
Terminal​
F1​
-​
S1 ‐Fuse (on fuse/relay panel)
10A​
Washer nozzle heaters, glove compartment light
-​
F2​
-​
S2 ‐Fuse (on fuse/relay panel)
10A​
Turn signal lights
-​
F3​
-​
S3 ‐Fuse (on fuse/relay panel)
5A​
Fog light relay
58​
F4​
-​
S4 ‐Fuse (on fuse/relay panel)
5A​
License Plate Light
58​
F5​
-​
S5 ‐Fuse (on fuse/relay panel)
7,5A​
Comfort System,
Cruise control,
Climatronic A/C,
Heated seat control modules,
Automatic day/night interior mirror
15​
F6​
-​
S6 ‐Fuse (on fuse/relay panel)
5A​
Central locking system
-​
F7​
-​
S7 ‐Fuse (on fuse/relay panel)
10A​
Back−up lights,
speedometer vehicle speed sensor (VSS)
15​

I don't have a VIN so this is best guess based on the car listed on your profile info. S11 is listed at ignition switched power to cluster, S15 is listed as battery constant to cluster.

109 relay is switched (ground control) by the ECM and gets its power from the same circuit that provides battery power to ignition switch. Ironic but fuse for radio comes from same source.

BTW - Double DIN radio has no switched power, just battery and ground. It waits for CAN buss signal from Cluster to turn on.

ECM can command AC off and depending on exact year AC and/or cluster can command AC off. Also depending on exact year cluster or ECM can command fans on for engine cooling. I don't remember if the earlier cars like these do it, but newer cars the fan control module will command fans on if the module looses communication with ECM.

Jason
VIN: 3VWRP69M73M027013

" fuse for radio comes from same source. "
Well my radio isn't powering up so maybe this is the culprit. Not sure if this is a fuse issue though? I probably need to pull open the ignition switch and see what kind of nasty corrosion is in there. I actually ordered a new one figuring it could be related to the relay109 issues. 3 weeks and counting waiting for it from idparts.

I believe my cluster is still good btw. When I got the dashlights working I used a flashlight to stare right into the mileage/clock and I could barely make out some numbers. I think they are just super dim from water damage on the LCD or whatever lights that up. I've seen that happen with other electronic devices. Not sure if that's something I can repair, prob not. I'm probably looking at getting a new cluster and having to go through all that fun immo coding stuff. But at least I know it's probably working.
 

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
Stock radio?

I think you have a more serious issue from what you have posted so far. Almost need to take every connection apart, clean it, put it back together if it all got wet like you said. Cluster may be dying a slow death and part of the reason functions are sporadic. Also concerned what the inside of the relay panel looks like if water got in there.

109 relay gets battery power directly from S176 (strip fuse on top of battery) by way of the cable bolted to the bottom of the relay panel. This circuit splits off at the relay panel and feeds the ignition switch, the 109 relay, and the fuse for the battery power to the radio (as well as a bunch of other things). ECM then grounds the relay, which then sends power to the solenoids for the engine (like N75 and cold start solenoid).

Relay 109 and numbered pins - pin 2 is 30 power from battery, pin 6 is switched power to engine solenoids and such, pin 9 is where engine provides the ground to activate the relay. Remove the 109 relay, check pin 2 for battery voltage. Turn ignition on and check pin 9 for ground. Jump battery power to pin 6 and you should hear at least one solenoid click. Those relays had a reputation of failing internally, too.

Radio should have battery voltage at the 2 red/yellow wires(the big ones) and ground at the ground.

So S5 feeds power (through a splice in the harness) the recirc button (along with a dozen other things). S225 feeds the blower fan switch - the power for the AC button comes off one of the wires at the blower switch (fans have to be on for AC button to work). The AC button sends power to ECM and Fan control module (just a signal, not the full load needed). Another fuse S16 gets its power from same place as 109 relay and powers up the fan control module. Now the fan control module, G65 AC pressure sensor, AC compressor clutch, and both fans all go to same ground engine left. G65 AC pressure sensor sends signal to ECM and the fan control module. Also the cluster has a dedicated wire to fan control module - this is important because if the cluster is messed up it could be sending a signal to fan control module to switch off AC.

Jason
 

DudaEnergy

Well-known member
Joined
May 4, 2015
Location
Madison, AL
TDI
2003 VW 1.9L
Kenmore radio. Installed by the prior owner. There's a wire added to the fuse box that appears to run to the radio.

I did verify that relay109's pin 9 isn't getting the ground when the ignition is turned to on. I've been jumping my car from pin 6 to pin 2 for a few weeks now just to drive it. Does the ECM directly ground this pin, as in, I can go check the ECM pins to see whether the cable is loose?

The relay panel doesn't look too bad. A few connections are a bit rusty. A metal fuse looked horrendous which I replaced with a standard fuse. It's getting power but no idea what it runs.

I think at this point I need to get the cluster replaced. The major concern here is the immo. I need to get the pin to be able to change the cluster and I read a professional with the right equipment needs to get it? Who should I be looking for for this? Is it going to be local people or am I taking the cluster out and shipping it off to one of the few that can do it?

So in summary, a connection to the ECM is likely bad for running relay109. The cluster is malfunctioning which could be the cause of the AC not turning on. But the ECM also has to do with the AC and with it being a problem for running the relay, could also be the problem with AC. So sounds like my main objective now is to go checking pins on the ECM. Is it possible to disconnect the harness and check the ECM pins directly? I guess I'd have to rig up something to power it to do so? I know I did see a pin-out in one of the forums so I should be good there. Just not 100% sure how much fun this is going to be trying to find out if it's the ECM itself or the connection between the ECM and whatever component it's trying to run.
 

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
ECM directly grounds the 109 relay. Maybe simple like a broken wire? Or maybe the transistor driver is fried?

Rust?! ANY rust and corrosion and I would be suspect of that relay panel. You'd be surprised what the insides look like.

I have seen a few places online that rebuild clusters. Some specifically for MkIV so you have more modern MFI added. Immo can be deleted at that time so its no longer a problem, if that's your thing.

Extra wire for radio is normal. VW did not have a switched wire to radio anymore so have to add a wire for aftermarket radios.

Jason
 

hopcarolina

Well-known member
Joined
Jan 20, 2012
Location
Huntersville, NC
TDI
2000 Jetta, 1990 Corrado TDI
Hello all,
Here is my scenario...

2000 Jetta TDI.AC temps went warm. Checked fan operation and nothing. AC clutch not engaging. I was hoping for low pressure. Hooked up the blue hose and can to top off and the low pressure side was in the red. Sorry I don’t have actual pressures.
I checked all the fuses and they are good. I got wired the fans and each one works fine. Slow and fast. I will be checking power to the FCM and compressor next. But, something triggered this. Could it be a stuck expansion valve? The compressor went bad? Curious if I should hot wire the compressor to check it?

thanks for any insight.
 

Nevada_TDI

Top Post Dawg
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
When my fans died, the smaller one had melted around the contacts, and the larger one quit turning.
A quick trip to P&P netted me the two fans for $30.00.
I did not know why my A/C was not cold, and thankfully it was the fans.
 

hopcarolina

Well-known member
Joined
Jan 20, 2012
Location
Huntersville, NC
TDI
2000 Jetta, 1990 Corrado TDI
Hello all,
Here is my scenario...

2000 Jetta TDI.AC temps went warm. Checked fan operation and nothing. AC clutch not engaging. I was hoping for low pressure. Hooked up the blue hose and can to top off and the low pressure side was in the red. Sorry I don’t have actual pressures.
I checked all the fuses and they are good. I got wired the fans and each one works fine. Slow and fast. I will be checking power to the FCM and compressor next. But, something triggered this. Could it be a stuck expansion valve? The compressor went bad? Curious if I should hot wire the compressor to check it?

thanks for any insight.
Yes Dan's checklist is an AWESOME resource! Still using it!!

update: I traced power to the fan control and good there. I decided to just jump the thermoswitch and let the fans run. I started the engine and turned on the AC and everything worked!! Possibly a bad thermoswitch. more research to follow. I thought the switch only worked for water temps and the fan control operated the AC condenser fan... back to check list...

Thank goodness the compressor didnt blow!!!!
 

Figit090

Veteran Member
Joined
Jun 21, 2015
Location
Northern California
TDI
Lifted Unicorn! '03 Jetta GLS TDI Wagon, 5spd, Candy White, Black leather.
Thanks to this sticky, I fixed my driver's side fan. I don't think I knew it was dead the entire time I've owned my car! After turning on the car and A/C, only one fan would run. When I fiddled with the fan on the driver's side, it tried to spin with pressure on it, but died if I let go; that solidified the notion it should be running, so I placed an order with FCP Euro and replaced it within the week. A/C functions much better now! I didn't bother opening it, but I'm going to guess the brushes/armature were quite dirty and worn.

 

Marchena

Member
Joined
May 6, 2021
Location
Norway
TDI
Skoda Octavia Scout 2.0 TDI BMM, Volvo S40 1.6 D4164T
EDIT: The issue is solved. I hooked up VCDS and found error codes on fan control module. Another observation was that the HVAC module asked the radiator fan to operate but it didnt. Swapped out the complete fan assembly with both fans, and the fan control module integrated in the main fan.

Fans are running and condenser and cabin getting cooled.

I guess 15 years and 240k km can wear out that control module 👍

———
Hello everyone,

I realise I have the "wrong car" but the systems seem very similar and it looks like there is a lot of competent people in this thread.

I have a Octavia Scout 2007 BMM engine that has a new compressor, G65 sensor, condenser and expansion valve. Today it was in for a vacuum and regas. The garage told me it was blowing cold air for 10 seconds and then no more. The condenser gets extremely hot and the fans are not turning on. The fans did however turn on and the AC worked fine when they forced the fans to run via diagnostic equipment.

They did find the fault code P01274 - but they dont know of this is related to the Condenser Fan(s) not turning on.

They suggested I could maybe wire in a switch to manually turn on the condenser fans to get the AC working, but I'd rather find out what is wrong, and I'm not even sure this would work.

Some history:
I have also seen the fans running after I changed the high pressure N65 sensor and regulating valve on the old compressor and recharged the system with a DIY gas. This was in a cool evening, and the AC worked. The day after, when it was pretty warm outside, the fans did not run and the compressor pressure relief valve blew. It gets very hot and high pressure when the fans are not running.

After this I decided to replace the compressor, condenser and expansion valve because I thought there was something wrong with the pressure not engaging the fans via the N65 sensor, but it seems like the fan operation is the problem, or atleast part of it.

After a lot of stupid decisions (should have gone straight to a dealer with proper AC gauges and diagnostic equipment first) I now believe something is wrong with either the fans or the electrical system before the fans.

I am posting here while still having troubleshooting left to do - but with limited time available before a road trip through Europe I decided to post here and see if someone can point me the right direction.
 
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OlyTDI

Veteran Member
Joined
Dec 18, 2007
Location
Olympia, WA
TDI
'04 Golf
My '04 Golf drive's side (DS) fan stopped working on low per the regular check procedure outlined in DanG's first post. The PS one works as it's supposed to but sounds gritty. I'm up for replacing both but am hoping for a little direction before doing that.

The AC still works fine. The PS fan works. The DS fan doesn't but will try ever so slightly to turn if I bang on the housing with a tool. Than makes it look like a brushes issue as outlined as the most common problem. And why wouldn't it be after 200K miles and 17 years?

I would assume that this means that just replacing both may very well solve the problem. Would the brain trust agree? I have far less time than money right now and since both have an issue, I think just replacing them is a low risk proposition.

My other question has to do with OEM vs either the Nissens fans or TYC duel cooling fan assembly found on IDParts. There is a huge price difference between the VW and the others. Are these aftermarket fans reliable or do I have to choke down the price for OEM?

Any info appreciated!

BTW, where's DanG? Looks like his last post was in June?!?

Thanks up front! - Eric
 

Figit090

Veteran Member
Joined
Jun 21, 2015
Location
Northern California
TDI
Lifted Unicorn! '03 Jetta GLS TDI Wagon, 5spd, Candy White, Black leather.
My '04 Golf drive's side (DS) fan stopped working on low per the regular check procedure outlined in DanG's first post. The PS one works as it's supposed to but sounds gritty. I'm up for replacing both but am hoping for a little direction before doing that.

The AC still works fine. The PS fan works. The DS fan doesn't but will try ever so slightly to turn if I bang on the housing with a tool. Than makes it look like a brushes issue as outlined as the most common problem. And why wouldn't it be after 200K miles and 17 years?

I would assume that this means that just replacing both may very well solve the problem. Would the brain trust agree? I have far less time than money right now and since both have an issue, I think just replacing them is a low risk proposition.

My other question has to do with OEM vs either the Nissens fans or TYC duel cooling fan assembly found on IDParts. There is a huge price difference between the VW and the others. Are these aftermarket fans reliable or do I have to choke down the price for OEM?

Any info appreciated!

BTW, where's DanG? Looks like his last post was in June?!?

Thanks up front! - Eric
I bought Nissens, seems good so far. Wire was extra long compared to OEM but tucked away nicely. Nissens is a good brand I believe. IDparts is OOS but looks like FCP Euro has them available:


The photo I posted above is a Nissens fan. I only replaced one because the small one was fine. To verify fitment (should be fine I checked) enter your car and go to Cooling System->Cooling fans

Good luck!
 
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energyflux00

Well-known member
Joined
Jun 22, 2015
Location
Syracuse, NY
TDI
Manual 5-Spd 2000 mk4 1.9L Jetta 187,000mi ALH
Hey folks,

2000 TDI Jetta -- 190,500miles. 6-7 years ago I replaced the magnetic A/C clutch, and both fans (as only one fan was running, AND the magnetic clutch was shot). The compressor is still original and the high and low side pressures have always been within a healthy range.

Earlier this summer in July, when the compressor WAS working (but the temp blend doors weren't doing their job as the foam on them failed) my pressures were about 35psi on the low side and about 150psi on the high side WITH the compressor running. Both radiator fans were also working at this time.

Earlier this summer in August (only 2-3 weeks after testing low and high side pressure), I tore apart the center console and taped the temperature blend doors (the foam failed on them). At this point the fans had stopped working for about 2 weeks and the compressor no longer kicked on.

Here is the current puzzle I am working with:

All fuses and terminals are good.

The light on the A/C switch on the dashboard turns on/lights up. If I am not mistaken, if the magnetic clutch is bad, it wouldn't light up, am I correct?

I am getting about 4.5 volts that go to the A/C compressor with the A/C button on the dash turned on, and the car ignition/key turned to "on" as well (at the plug directly off of the compressor). And I am also getting 1.0-1.1 ohms reading here. From my understanding, if I am not getting power at all at the compressor, fingers get pointed at the FCM. And that more than 4.5 volts (i.e. 12 volts?) are needed to kick on the compressor, which is determined whether or not the fans are spinning as a safety switch.

Neither of my radiator fans are working. I have read that usually one dies first and then the other dies after it (which was the case when I replaced both of them 6 years ago). But this time they both just stopped working within the same 2-3 weeks of them both working. So I am not sure if the problem is the fans or not, and am unsure of how to make sure it isn't due to low side pressure being too low and locking out the fans and magnetic clutch if the compressor isn't working. Considering I am getting power to the compressor (just not enough to kick it on??) AND the fans aren't spinning, AND when I tested low and high side pressures mid-summer they were good, I am thinking that the problem are the fans.

The FCM was replaced 6 years ago as well, but with one I pulled from a junk yard (which also turned out NOT to be the problem back then).

If the FCM is bad, would power still be going to the compressor?

My understanding is that if the neither of the fans are working, they won't spin at all and the compressor won't turn on as a safety. But again, this could also be a lockout due to low pressure on the low-side of the refrigerant system.

Before I start throwing parts at this, does this sound like bad fans to any of you? I have read the articles in this thread but am getting a little stumped here.

Is there a way to test the low side pressure without the compressor running to make sure it isn't low side pressure locking out both of the fans and magnetic coil? From my understanding, the compressor needs to be running to get an accurate reading of low and high side pressures.

Thank you! This forum is awesome.
 

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
4.5V sounds like the FCM self test voltage. That's how the computer tests to see if there is open circuit. Put a regular test light on that and I bet the voltage goes away. More likely there is a fault and the ECM or FCM is disabled the AC. And first on the list is low Freon or bad G65 (pressure sensor), though on 2000 it may be the older pressure switch instead of pressure sensor. If the car was gas I would say go to ECM and check AC shut off code, but on a 2000 TDI I'm not sure if that MVB exists. May be someone from Ross Tech can jump in on that one.

Jason
 

noob_tl

Veteran Member
Joined
Mar 30, 2012
Location
Central Indiana
TDI
2003 NB
2 Fans, 4 Failure Modes

When my daughter said her AC wasn't working well in town a few weeks ago, I knew where to look thanks to this thread. In short, both fan motors had failed. They seem to be the originals (Valeo and VW logos on them), 18 years old and 276,000 miles, the 2003 NB in my sig.

Having nothing to do on a rainy Sunday, I tore them down to see exactly what failed. One was what I expected, the other was quite a surprise!
When I pulled the cover off the large fan, it looked normal:

The small fan, however, was quite unexpected:

I've never seen a commutator slide down a shaft, I'm not even sure how it happened.


The brushes on the large fan are worn out (right) but the ones on the small fan still had a lot of life left. That fan must have failed quite some time ago.

The resistor on the large fan had eroded and failed, so the slow speed operation must have failed before the brushes wore out.

Likewise, the slow speed resistor failed on the small fan, but not in the same way. The solder joints near one end of the resistor fractured. Not just fractured, but the solder itself is missing, so I'm guessing it got hot enough to melt and run off, leaving a weakened joint.

Just thought I'd share a result I found surprising.
 

lardope

Veteran Member
Joined
Jan 16, 2018
Location
Pennsylvania
TDI
MKIV
Bad Fan?

Without reading through all 67 pages of responses (lol), one of my fans is not working. I put the key in the ignition in the on position, turned on my AC, and set the blower to low. I then tried all the blower settings. I have an MK IV.

This is a problem, yes? What should I replace? Thanks!
 

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
Probably the low speed portion of the fan failed…….so yes it’s the fan…..
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Yep, typically the low-speed portion. Its a resistor inline and it burns up. Change it, however, as over time if you don't the extra stress on the A/C system in the summer months will likely destroy the compressor.

As pressure rises with the TXV controlling flow of refrigerant through the evaporator the bypass percentage via the RCV goes up and the means of getting the heat out of the compressor is the circulating refrigerant. Thus if the condenser is not getting adequate airflow (e.g. dead fan(s)) and the temperature is high the compressor cooks, the oil in it cokes and that's the end of the show.
 

MVP

Veteran Member
Joined
Feb 15, 2015
Location
Litchfield Park, AZ
TDI
2003 Jetta Wagon, GLS 5-speed, Baltic Green Past: 2001 Golf 4-door, GLS 5-speed
Bad Fan?

Without reading through all 67 pages of responses (lol), one of my fans is not working. I put the key in the ignition in the on position, turned on my AC, and set the blower to low. I then tried all the blower settings. I have an MK IV.

This is a problem, yes? What should I replace? Thanks!
Post 1 and post 10 told me everything I needed to do. I replaced my fan a few years ago and problem solved. YMMV.
 

Searcher2

Veteran Member
Joined
Oct 9, 2014
Location
Bossier City La.
TDI
'98 Beetle tdi
I'll admit I haven't read all 67 pages of this thread, but I need some info. My manual is supposed to cover 1998 to 2008 Beetles. My wiring diagram is for a T14 FCM and the 98 is a T10. Are the wiring colors the same on the T10 and T14? How is the connector numbered for the wiring positions? More questions coming later. Thanks for any help.
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
The connector itself will have numbers stamped or embossed on the connector housing itself. Somewhere.
 

Searcher2

Veteran Member
Joined
Oct 9, 2014
Location
Bossier City La.
TDI
'98 Beetle tdi
Thank you Nuje. I will take a look later this morning. I'm sure that somewhere in the checklist I'm going to find a disconnected plug. It would be strange if a component decided to fail at the same time I had the compressor and fans disconnected and manipulated to allow for r and r of the alternator.
 

flan

Veteran Member
Joined
Jul 3, 2014
Location
On my couch
TDI
04 tdi jetta
My 04’s ac has faded from last summer time, so I checked the fans and found both mine work on low key on, ac on, engine off. I’ll have my friend with ac machine take a look for leaks and charge if good. I have had my car since 13 and never added refrigerant so I wouldn’t be surprised if it was a tad low.
 

Richy_T

Veteran Member
Joined
Apr 18, 2007
Location
Dickson, TN
TDI
2000 Jetta
Just to follow up on my situation, it was the fuse. It's still intermittently a problem. It seems it will settle into a position where the contacts don't properly touch the fuse. Moving it slightly will make things work again for a while. Typically I only get to find out when I'm several minutes into a journey and things aren't getting cold, of course. I'm probably just going to try and bypass the fuse with an inline fuse holder. I did try and squeeze the contacts back together but that didn't seem to help much.
 

CantWrite

Veteran Member
Joined
Jun 8, 2021
Location
Placerville CO
TDI
2005 Passat Wagon (BHW/5-spd conv, 03T). I keep in touch with the (2) ALH's I sold.
@Richy_T, what about "tinning" the spades of the fuse before bypassing all together? Not sure if you can build up enough solder to account for the relaxed socket.

I am no expert, and do not wanna give bad information, just a thought before you go cutting the factory harness.
 
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