Check your radiator/condenser fan operation NOW

[BettyWhite]

Fixed

Your immediate problem is a lack of power on T14/4.
Check the wire by piercing it, to see if it has voltage.
The most common fail point, after the fuse, is the electrical joint right at or inside the T14.
If that is the problem, you can buy a repair wire at VW and replace that section of wire and the connector.

Pierced the wire with the connector hooked up and the voltage read around 1.12 volts. T14/Pin 4 it is.

Though, I wasn't feeling too confident about cutting the section of wire out, I took the car to a local shop. The mechanic added in the new section of wire, I hit the AC button and now my AC works! My pocket is $50 lighter for his labor, but I'm glad the job is done.

Thanks for the help Dan and everyone

 

[BobnOH]

Yea man Dan is awesome! The tiny wires on our cars do give trouble as they get older.
All sorts of hard to find issues. It's easier to diagnose a current supply wire, many of the others you can only check resistance, easily. And some will test fine for continuity but fail when called upon.

 

[commanderjjones]

After 2 summers of dealing with intermittent AC issues, I have finally traced the problem to a sketchy connection at the AC pressure switch. The switch itself is fine but it seems to be a problem with the connector. Anyone know where I can get a new plug end? That doesn't seem to be something that the auto parts store sell.

 

[DanG144]

You can get repair wires from VW and splice them in. You can remove the existing wires from the connector, if you study up on it. Or VW will sell you a new connector as well.

Or you can go to a salvage yard and get one.

 

[Jesterking]

Hello out there,
First post here..new to the group..
Just bought a 2005 (built 06/2004 ) Jetta GLS TDI, 5 Speed...it has 296,000 miles on it..but is in pretty decent shape..seems to run decent..I drove it back and forth to work the last couple of days, 133 miles a day...and according to my math, I am getting 52.5 MPG..that's the good part, the bad part is, I am trying to figure out why my AC doesn't work...It appears I need to move close to Dan, as he seems to know an awful lot about this subject..what I do know, is the test of turning on the key and pushing in the AC button and blower to low, gives me an AC light, but looking under the hood reveals no fans rotating... I attempted to get the fan switch connector off of the switch, but I am unsuccessful, as the engine was pretty warm, and I kept burning my arm as I reached down there, it started pouring rain, and I was a little timid in breaking something off as I am not so sure of the release mechanism on that connector. Both fans will rotate when turned by hand, one of them ( Driver's Side looks very new ) A/C compressor Rotates when turned by hand. Gauges show presence of gas pressure...Just need to figure what link is missing..
Fuse block on top of the battery appears to have been replaced..doesn't show the same age as everything else under the hood..wires look very new...

Any suggestion would be greatly appreciated.

Jesterking

 

[cbman18j]

Jesterking,
You should check to see if you fans are see 12 Volts from the FCM. A quick way to see if your fans are good is to provide 12V momentarily to the fans in order to verify that the fans operate. Just because it looks new doesn't mean it is a working part. If your fans work then you can find out why they aren't see 12v. One time I had a bad fan another time a wire going to my FCM under the battery had corroded thru so no power going in or out.
Chris

 

[DanG144]

Jester,
practice on the coolant system level sensor connector on the reservoir. It is similar to most of the ones on your car.
You have to push down the axis of the connector, as if pushing it deeper into the socket. Then squeeze on the lever tip radially, to lift the far end of the lever off of the catch, then pull outward axially.
Even when you are certain you know how they work, they can be tough to work with. Patience helps, as does wiggling it sometimes. Putting tools on the lever usually breaks it. If your lever is broken, you can sometimes insert a dental pick in under the edge furthest from the wire and lift it up.

I guess you are trying to do the fan troubleshooting in post #1?

 

[Jesterking]

Jester,
practice on the coolant system level sensor connector on the reservoir. It is similar to most of the ones on your car.
You have to push down the axis of the connector, as if pushing it deeper into the socket. Then squeeze on the lever tip radially, to lift the far end of the lever off of the catch, then pull outward axially.
Even when you are certain you know how they work, they can be tough to work with. Patience helps, as does wiggling it sometimes. Putting tools on the lever usually breaks it. If your lever is broken, you can sometimes insert a dental pick in under the edge furthest from the wire and lift it up.

I guess you are trying to do the fan troubleshooting in post #1?

Yes, I am...not having much luck...between leaving for work at 4:30 am and not getting home until after 7:00 most nights...not a lot of time to chase this rascal..I appreciate the suggestions...
Attempted disconnecting the connectors again...am not able to get the fan switch connector to move... not having much luck with the individual fan power connectors either..coolant sensor appears to be rectangular...fan switch 3 prong triangle..

 

[DanG144]

The three prong triangle is the radiator thermoswitch. The fan connectors are flat three conductor, stacked next to each other.

All of them have latches that work the same as the coolant sensor - there is a lever protected in a housing that protrudes from the side, despite their overall different appearance.

 

[ymz]

All of them have latches that work the same as the coolant sensor - there is a lever protected in a housing that protrudes from the side, despite their overall different appearance.

The coolant tank connector on the older cars is different: its release levers need to be pushed in from both sides... the fan connectors are similar to the ones on the MAFs, backup switch, front brake wear indicator, etc...

Yuri

 

[DanG144]

Good point, thanks.

 

[Jesterking]

Well.. I will attempt to get underneath the car using a set of ramps...maybe that angle of approach will be more productive?!
I really appreciate all of the points of information and suggestions !!

JK

 

[DanG144]

If you try to look at it from the bottom, you will have to remove the belly pan (lower engine cover) Takes a 25Torx and a 30 Torx, I think.

You can see it from the top.

 

[michaelbailey777]

question towards the original post of this forum. i was recently driving with my AC on and it just went out all of a sudden. i went home and looked and the compressor clutch isn't kicking on nor the fan working. i did all the troubleshooting and replaced both CTS and thermo switch along with the thermostat, still have nothing i also went to a junkyard and picked up 2 fan control mods for like 5$ and neither of those worked. today i went and tested the fans (with ac and fan motor in car running) jumped from the thermo switch connector and also individual fan connectors and this is what i got at the thermo switch i can jump it to get both fans running on high speed but no low speed on the AC fan from either connector.

went and tore apart the motor of the small fan and it looks like it started on fire lol. the plastic looks like charcoal. the brushes looked fine. so my question is if i replace the low speed fan will this solve my problem of my fans and ac not working do you think? i'm sure someone on here has had this problem. and why would the fan even though its burnt up like it is still work when i put power to it for high speed? any feedback would be nice. this is the first time dealing with these electric motors on vw fans. also how well do the ebay fans hold up? i mean the oem fans are almost 300$ compared to 86$.

 

[DanG144]

It sounds to me as if you have a bad AC compressor electric clutch, and bad low speed fan circuits. This is just a guess, on the clutch. I would put 12 volts and ground to the clutch coil and see if it would engage. When you hear your opening statement "i was recently driving with my AC on and it just went out all of a sudden" it is often the clutch coil failure.

The fans have two circuits. Slow speed goes through a resistor to drop the voltage (which also puts tremendous heat inside the fan), this circuit can fail, often at a solder joint or crimp, but the high speed circuit which puts 12 volts directly on the brushes will still work.

Additionally the full 12 volts will often pass enough current through poor brush contact enough to spin the fan, where the lower voltage will not provide enough current.

The plastic brush holders melt to the brushes and prevent them from having adequate contact pressure on the commutator. When trying to run in slow speed some current still flows, producing heat, but there is no air flow, so the heat stays inside the fan motor housing.

The Dorman fans fail very often - quite often within a few months. You will need to watch them and test them often, and replace them often. The VDO fans are better, but still have too high a failure rate to make anyone happy. I wish I had better news for you on the fans.

 

[DanG144]

Michael,
if the clutch coil is good, look at your electrical connectors on the FCM. The wires and connectors often corrode and fail where you live.

 

[Jesterking]

https://www.rockauto.com/en/catalog...163,cooling+system,radiator+fan+assembly,2181

I have found the prices here are pretty reasonable...a lot of times they offer the OEM parts and an upgrade option as well ( Brake rotors and Pads for example)
Just my $0.02

JK

 

[Jesterking]

Jesterking,
You should check to see if you fans are see 12 Volts from the FCM. A quick way to see if your fans are good is to provide 12V momentarily to the fans in order to verify that the fans operate. Just because it looks new doesn't mean it is a working part. If your fans work then you can find out why they aren't see 12v. One time I had a bad fan another time a wire going to my FCM under the battery had corroded thru so no power going in or out.
Chris

Here is what I have found so far..

Driver side fan will run in slow and high speed

Resistance checks:
Pin 1-2 1 Ohms
Pin 1-3 1.6 Ohms
Pin 2-3 3.4 Ohms

Passenger side fan will NOT run at either speed

Resistance checks:
Pin 1-2 1.2 Ohms
Pin 1-3 16.5 Ohms
Pin 2-3 21 Ohms

Key on, AC on, blower on low, AC lights up,

NO voltage present at either Fan connector.

Am still having some difficulty trying to figure out how to disconnect the the fan therm o-switch..I can see it..I can put my hand on it..just not sure what I am supposed to be doing with the latching mechanism to release it. I believe the mechanism is on the underside of the switch. There appears to be a tabs on the upper area..I have pulled, twisted , pried ( as much as I can with one hand), I am unable, so far, to get it off...

 

[DanG144]

There is a lever on the side of the connector that has to be pushed in to lift its far end. Very similar to the fan connectors.

http://pics.tdiclub.com/data/516/A4_Coolant_Fan_testing_Rev_7.pdf shows end views and sketches of the connector. The end of the lever in the square housing on one side of the triangle has to move away from centerline (lets call that 'UP") , in order to do that you must push down on the other end of the lever.

So what did you determine from your readings?

Do you know if your AC electric clutch is engaging? Does the face of the clutch and the center shaft start turning with the outer rim of the pulley when the AC is turned on?

 

[DanG144]

Have you gone through the fan troubleshooting and AC system troubleshooting guide in post #1? Checked all the fuses listed in the guides?

 

[Jesterking]

There is a lever on the side of the connector that has to be pushed in to lift its far end. Very similar to the fan connectors.

http://pics.tdiclub.com/data/516/A4_Coolant_Fan_testing_Rev_7.pdf shows end views and sketches of the connector. The end of the lever in the square housing on one side of the triangle has to move away from centerline (lets call that 'UP") , in order to do that you must push down on the other end of the lever.

So what did you determine from your readings?

Do you know if your AC electric clutch is engaging? Does the face of the clutch and the center shaft start turning with the outer rim of the pulley when the AC is turned on?

I have disconnected just about every other connector under the hood, practicing to master this...I FINALLY got it off...WOW..what a pain!!!

What did I determine??
Passenger side fan is dead...It won't work when jumpered..
Driver side works in both slow and high speed

I wasn't getting any voltage to the Fans, when I had the key on, AC on, and blower to low...so I would tend to believe that the FCM isn't doing it's job either..

Now that I have the fan switch disconnected, I will jump it to eliminate it from the list of suspected parts..

I am not getting any clutch action..I can rotate the compressor by hand...there is some minimal resistance, but the gauges show pressure in there, so not sure if that is what I am feeling

 

[Jesterking]

Have you gone through the fan troubleshooting and AC system troubleshooting guide in post #1? Checked all the fuses listed in the guides?

All fuses and connections on top of the battery look clean..( actually they look new...) no signs of corrosion..connections are tight..fuses look good, no corrosion in the sockets..

 

[DanG144]

Sorry, but this is not good enough. Check all the fuses listed in the PDF's in the first post, for your car. Start with the simple stuff, sometimes you get lucky and can avoid hours of thought and work.

 

[DanG144]

In my opinion you can stop trying to test from the thermoswitch. Now that you know one fan is good, and the other needs repair or replacement, you can go on to AC troubleshooting. Once you have finished checking the fuses. You do know there are lots of them in the cabin, on the side of the panel by the driver's door?

Ensure that the power from your good fuses are getting to the proper pins in the FCM.

I will stick with you.

 

[BettyWhite]

New battles on the AC frontier two weeks after fixing the fans and the T14/Pin4 wire on the FCM connector, but I'm ready for the fight. Thanks for the help in the past Dan!

Today, I noticed while idling at a stoplight with the AC on the air temperature from the vents started to become slightly warmer. Still cool, but not as cool moments prior. When accelerating or cruising at any speed (30, 40, 60 mph) the air temperature with the AC on felt perfect (by that, I mean very cool).

In my driveway, I verified that the passenger and driver fans engage when the AC is turned on and an interior fan speed is selected. I noticed at full blast (state 4 on the interior fan dial), the AC clutch isn't always engaged, as a matter of fact, its rate of engagement isn't predictable at all. I'm not sure if this behavior of the AC clutch is commonplace, but I'm wondering if the AC Compressor Clutch or Coil is going bad.

While driving I can feel a actuator being engaged/disengaged while the AC is on. I'm fairly certain this is the AC Compressor's coil. The frequency of the coil engaging seems to be a lot more present now than before.

Anyone know if this intermittent engagement a sign that the AC Compressor clutch or coil is failing?

Thanks everyone

 

[Jesterking]

In my opinion you can stop trying to test from the thermoswitch. Now that you know one fan is good, and the other needs repair or replacement, you can go on to AC troubleshooting. Once you have finished checking the fuses. You do know there are lots of them in the cabin, on the side of the panel by the driver's door?

Ensure that the power from your good fuses are getting to the proper pins in the FCM.

I will stick with you.

I do appreciate that!!

So, out to the car i went, and i attempted to short the radiator fan switch with key on, ac on, and blower low...NO Fans turn..I checked the for 12 volts on the red wire ( pin2) ...NO 12 volts...verified i had 12 volts at S180..it is GOOD, took off the 3 wire connector, checked for 12 volts coming out of connector..good.
jumped 12 volts to radiator fan switch pin 1...FAN WORKS...

Also turned Key off and tested Pin 2 of thermo switch...NO 12 Volts..

checked fuse 5, 16, and 25...all are good

 

[Jesterking]

Sorry, but this is not good enough. Check all the fuses listed in the PDF's in the first post, for your car. Start with the simple stuff, sometimes you get lucky and can avoid hours of thought and work.

Speaking of fuses...
I can look at the ones on top of the battery and check them with a VOM, as well as the ones in the cabin, however, I have no idea what ones are supposed to be where.. Here is what I have:

TOP Row left to right
Fuse 8 = empty
Fuse 12 = 7.5 amp
Fuse 16 = 10 amp
Fuse 20 = 15 amp

2ND ROW
Fuse 5 = 7.5 amp
Fuse 9 = 5 amp
Fuse 13 = 10 amp
Fuse 17= empty
Fuse 21 = 15 amp

3RD ROW
Fuse 1 = 10 amp
Fuse 3 = 5 amp
Fuse 6 = empty
Fuse 10 = 10 amp
Fuse 14 = 10 amp
Fuse 18 = 10 amp
Fuse 22 = 5 amp

4Th ROW
Fuse 2 = 10 amp
Fuse 4 = 5 amp
Fuse 7 = 10 amp
Fuse 11 = 5 amp
Fuse 15 = 5 amp
Fuse 19 = 15 amp
Fuse 23 = 5 amp

5TH ROW
Fuse 24 = 20 amp
Fuse 21 = empty
Fuse 30 = 15 amp

6Th ROW
Fuse 25 = 25 amp
Fuse 32 = 30 amp
Fuse 39 = 15 amp

7TH ROW
Fuse 26 = 25 amp
Fuse 33 = empty
Fuse 40 = 20 amp

8TH ROW
Fuse 27 = empty
Fuse 34 = 10 amp
Fuse 41 = 15 amp

8TH ROW
Fuse 28 = 15 amp
Fuse 35 = 30 amp
Fuse 42 = 25 amp

9TH ROW
Fuse 29 =10 amp
Fuse 36 = 15 amp
Fuse 43 = 10 amp

10TH ROW
Fuse 30 = 20 amp
Fuse 37 = 5 amp
Fuse 44 = 15 amp

 

[DanG144]

I do appreciate that!!

So, out to the car i went, and i attempted to short the radiator fan switch with key on, ac on, and blower low...NO Fans turn..I checked the for 12 volts on the red wire ( pin2) ...NO 12 volts...verified i had 12 volts at S180..it is GOOD, took off the 3 wire connector (which connector are you speaking of here? This is a bit confusing, checked for 12 volts coming out of connector..good.
jumped 12 volts to radiator fan switch pin 1...FAN WORKS...

Also turned Key off and tested Pin 2 of thermo switch...NO 12 Volts..

checked fuse 5, 16, and 25...all are good

So the next check is to see if there is voltage on the 4 pin heavy wire connector on the FCM, T4a/3 (supply from S180-30 amp for slow speed - which as you seem to know supplies the pin 2 of the radiator thermoswitch) and T4a/1 (supply from fuse S164-40 amp for fast speed).

It sounds as if you have a wire broken in there somewhere, it will help to know if the conductor is good to the FCM or not. There is a splice -k20- in the wire from S180-30 amp where it splits to go to the two places - FCM T4a/3 and Fan thermoswitch pin 2.

 

[DanG144]

New battles on the AC frontier two weeks after fixing the fans and the T14/Pin4 wire on the FCM connector, but I'm ready for the fight. Thanks for the help in the past Dan!

Today, I noticed while idling at a stoplight with the AC on the air temperature from the vents started to become slightly warmer. Still cool, but not as cool moments prior. When accelerating or cruising at any speed (30, 40, 60 mph) the air temperature with the AC on felt perfect (by that, I mean very cool).

In my driveway, I verified that the passenger and driver fans engage when the AC is turned on and an interior fan speed is selected. I noticed at full blast (state 4 on the interior fan dial), the AC clutch isn't always engaged, as a matter of fact, its rate of engagement isn't predictable at all. I'm not sure if this behavior of the AC clutch is commonplace, but I'm wondering if the AC Compressor Clutch or Coil is going bad.

While driving I can feel a actuator being engaged/disengaged while the AC is on. I'm fairly certain this is the AC Compressor's coil. The frequency of the coil engaging seems to be a lot more present now than before.

Anyone know if this intermittent engagement a sign that the AC Compressor clutch or coil is failing?

Thanks everyone

It could be the clutch coil, or it could be something else. But it is definitely NOT proper behavior. In the VW MK IV, the fan clutch should engage when the AC is turned on, and never disengage until you turn off the car or the AC, when the system is working right.

Do you think the wiring repair is good to the T14 pin 4? If this is intermittent you can get this behavior.

Also if the T14/ power to the AC clutch from the FCM or T14/ ground for the AC clutch is intermittent.

The FCM ground must also be good. This is one of the grounds under the battery. While you are there there are three grounds to pick up, clean and replace.

Your clutch coil resistance should be between 3 to 5 ohms.

 

[Jesterking]

So the next check is to see if there is voltage on the 4 pin heavy wire connector on the FCM, T4a/3 (supply from S180-30 amp for slow speed - which as you seem to know supplies the pin 2 of the radiator thermoswitch) and T4a/1 (supply from fuse S164-40 amp for fast speed).

It sounds as if you have a wire broken in there somewhere, it will help to know if the conductor is good to the FCM or not. There is a splice -k20- in the wire from S180-30 amp where it splits to go to the two places - FCM T4a/3 and Fan thermoswitch pin 2.

"Which Connector are you speaking of, this is a bit confusing.."
I was talking about the 3 wire connector that comes off the back of the Fuse block that sits on top of the battery

I will test T4a/3 and T4a/1 and attempt to narrow this down...