Hi all,l i have a 2005 1.9 TDI AVF engine, the electric condenser fan (driver side) will cycle off and on to a high speed as necessary with the AC turned on but as I understand it the fan should run at a lower speed with AC on and cycle up to a higher speed when required for cooling, (ie always on when the ac is on). has anyone come across this, looks like the low speed function is not working, I have come across some info on Passat forums but not sure how much applies to the Superb. The AC works and has just been serviced with no leaks in the system.With the low speed not working it is cycling to the high speed more often and obviously not working as efficiently as it should putting extra stress on the components, any feedback is appreciated, has anyone had to replace this fan?

thanks

G

Edited 5 June, 201313 yr by gfinneran

I had a problem in December / Jan / Feb this year. Mine always ran in full blast mode as soon as you put the ignition key in. I couldn't find anything to help me fix this symptom on the Passat / Audio forums. My problem was the pressure sensor in the front bumper area which tells it to either do slow or fast speed depending on the pressure in the AC cuircut. You can unplug the electrical socket and short the prongs in the socket to check if it makes any difference.

Thanks Nackuk for the reply, I am leaning towards the resistor as the fan is not noisy and spins freely in the high speed mode, mine is cycling ok coming on high speed for approx 30 seconds and then off completely which it should just drop back to low speed operation with the AC on.I found an issue highlighted on the Passat forum with moisture getting into the resistor and failure of the low speed function through corrosion see below.I wonder how many people fail to realise this fault in our cooler climate, car will not be overheating and the AC works but intermittently so harder to spot.

I will update when I find out more but it is easy to check the correct function in a few minutes and could potentially save yourself time and money down the line, I have read one incident of the electric motor burning out literally and catching fire luckily the owner was right there to put it out before it spread. Hopefully this will be of help even if its just for a smoother running AC in our June sunshine (long may it last)!

G

This is from Passat world,

Neutral Join Date Jul 2008 Posts 3

Hello Andy,

UK here as well, Maidenhead Berkshire to be precise.

I've just been through this with my 2002 B5.5 TDI(130) Engine code AWX.

Exactly the same as you, my aircon hissed and cut out stuck in traffic.

No fan movement at all (leccy one).

This is what you need to do (in order);

1, Remove scuttle panel above pedals and check both the 40a and 5a fuses. These are located on the relay panel (the one at the back up under the pedals). If ok, then,

2, Disconnect fan (conntor plug under power steering res cover) and connect direct to battery. It's a good idea to use a fuse to do this. If fan does not spin, tap it with something heavy. It might slowly spring into action. If ok, then,

3, Remove under tray and pull of connector to fan switch on bottom hose. Look at the connector and you should see 4 numbered terminals. At this stage leave fan disconnected. Ignition on, bridge terminals 1&4 to activate high speed circuit / relay, then bridge terminals 2&3 to activate low speed circuit / relay. The purpose of this part is to check the power circuits and relays for the low and high speeds. Carefully listen for the relays clicking up under the pedals (where you checked the fuses) or get the Mrs to listen. If ok, then,

4, Reconnect fan (connector under power steering cover remember) and repeat the bridging of terminals in 3 above. Note if your fan sprung to life when you tapped it, as a minimum you should get the high speed. On mine I got high speed but no low speed, in which case,

5, Get a voltmeter. Look up under the passenger side chassis leg right up at the front near the intercooler. You will see the fan resistor pack up there. This what was faulty on my car due to water ingress. You need to check each terminal in turn for 12v whilst the ignition is on and you have either the hight or low speed terminals bridged on the fan connector. You will note one of the connectors has two cables to it. This one should read 12v / battery volts when the high speed is bridged, less when the low speed is bridged. I got 12v on the two cable connector and nothing on it once the low speed was bridged. This led me to conclude that the fan resistor pack was knackered.

I ended up replacing the fan, the radiator (as it was suffering from the common Passat problem where it weeps on the lower engine side corners) AND the resistor pack. A dear old do, but it all now works perfectly.

The fan itself can be replaced with everthing insitu.

The rad requires removal of the bumper, removal of the bumper iron and setting aside of the aircon rad.

The resistor pack requires setting the lock carrier into the service position.

Not a difficult DIY job but the terminal 'nuts' on the resistor pack on mine were right buggers.

Talk to vagparts about the resistor pack (cheapest)

Piccy of resistor pack (my new one prior to fitting)

IM, Email, and Social Networks in one easy to use application!

IM, Email, and Social Networks in one easy to use application!

http://digsby.com

Also, as far as I'm aware, the fan control system is the same on US B5's as well.

And below the first post in a thread of over a thousand posts on the subject in on www.TDIClub.com!

Check your radiator/condenser fan operation NOW

Now is the time of the year to check that both of your electric fans for the radiator and air conditioner condensor are functioning. Do not needlessly age your Air Conditioning compressor by running it at too high a pressure and temperature.

A4's and A5's (I suspect others, too) have bad problems with radiator/condensor coolant fans not being operational.

There is no DTC or MIL light that comes on for this. No overt warning at all.

Most people do not notice anything until both of their fans have quit completely, and then they might notice that the AC compressor kicks off when at stop lights or in traffic. They may notice their AC is not as cool as normal. This is the terminal stage of this disease.

Here is the usual progression of this failure.

1)One fan slow speed operation fails, no one notices. The AC is operating at higher than normal temps and pressures, but still does a good job.

2) The second fan's slow speed operating mode quits; no one notices. The AC compressor is running even hotter and at higher pressures. When the vehicle is not moving, the pressure builds up to the high pressure point on the refrigerant pressure sensor. The high speed fans kick on, and the compressor kicks off; this lasts about 20 seconds, then the compressor kicks on and the fans kick off (they should be in slow, but that has failed. The cycle repeats about once per minute. Most people will still not notice this, as the refrigerant pressure stays high and they get some cooling.

3) The repeated cycling of the high speed fans, and their very high starting current will eventually cause some electrical connection or component to fail in the fan circuit. All fan operation is lost. This folks usually notice when they are at stop lights or in traffic, as the AC compressor will kick off and on repeatedly. Cabin cooling is usually affected, and many notice, but some think it is normal operation.

To avoid this scenario check your fan operation every time you check under the hood (every refueling, right?)

Manual AC (as opposed to Climatronic AC or Climatic AC -the transmission type is immaterial) cars, push the AC button in, place a fan in slow and leave your key to ON (engine does not have to be running). Both fans should run in slow (unless it is near freezing or your refrigerant pressure is too low.) If your AC light does not come on and your cabin fan does not work, do not proceed until you have troubleshot and fixed this problem; this is the primary signal to turn on the AC system.

Climatronic or Climatic AC cars (includes all A5 cars), with the engine running, select low cabin temperatures for climatronic or AC on fan on for Climatic, make sure you are not in ECON mode, and check your fans. Both should be running at a slow speed condition within about 30 seconds (they are infinitely variable in speed.) Again this is dependent upon not being in near freezing conditions and having adequate refrigerant pressure. Your fans key off of refrigerant pressure signals, so the compressor must be good and be loaded in order for the fans to see a high enough pressure to start.

During the engine output tests with VCDS, if there is a fan test (and there is on BEWs and BRMS) then BOTH fans should run together.

Some links to PDF papers on troubleshooting A4 fans and Manual Air conditioners. Please forward any questions or corrections to me (DanG144).

A4 fan troubleshooting

Sept 98 - May 99 Build date A4 Manual Air Conditioner Troubleshooting

Rev 7 May 99-end of A4 Manual Air Conditioner Troubleshooting.

Fan Repair

pinout of J293 Thanks to wulee

Refrigerant Pressure table vs temperature and G65 pressure transducer This is based solely on reading one (my own) pressure transducer; this is not guaranteed accurate. If you have the real calibration data, or data from your own transducer, please forward it to me.

__________________

Edited 5 June, 201313 yr by gfinneran

Hi, I have noted your problem maybe different but just trying to help as there isn't much out there on the Superb AC.

When I looked the only thing out there seemed to be pointed to this resistor pack too. I was going to check that myself but once I had read the circuit diagram and understood it - it was not likely to be that in MY case.

Anyway the pressure sensor can be unpluged easily with bumper off. Then there are two sets of contacts to short out in the plug while the AC is on. One will bring the fan on slowly. The other two contacts will bring the fan on fast.

If this works by shorting the contacts out - the sensor is no good. If not the fault lies else where - ie the resistor pack.

It is very simple to check with the bumper off.

Read this for help.

http://nackuk.blogsp...at-dam-fan.html

It would be good for us all if you let us know what the outcome is though as on the Superb as I say I couldn't find much help out there.

The sensor is dear so I hope its not that for you.

Update on this reseated the relay 373 behind the drivers kick panel (thanks to Francie) fan started up on low speed and has worked ok since so check fuses and relays first. I think there are more people out there with this problem but haven't noticed it, easy enough to check look at the post above, in short your condenser fan has 2 speeds low should come on when ac is on or auto if you have climate control, the high speed which is loud and you will hear it kick in should come on when high temps require more airflow over the condenser ( possibly in heavy stop start traffic in hot weather) hope this helps. G

As above. 

 

The fan should come on immediately when the A/C is turned on.  If it doesn't then check fuses/relays and failing that it's the internal resistor.

 

Had to do the resistor mod on my Passat (Cost around £29 for all parts from RS Components and took an hour to rewire) and it worked perfectly after that and an absolute bargain compared to the £360 VW wanted for a new fan,