[supercharged_v6]

Hi,

Well this is my girlfriends 1999 NEW BEETLE... anywho... well yesterday.... her car started to over heat... She pulls over and she says her fans arent working... It has done it before... Were the fans wont work... but then they misteriously do.... Anywho i told her to leave the car were it was and i would pick it up after work... Well we get there and we let the engine warm up and nothing... Fans still arent coming on... I told her to turn on her A/C to full blast to see if the fans would kick in and surely they did.. we were able to limp her beetle quite a distance until about a mile from my house... she was running the A/C and she quickly pulls over and turns off the engine and she tells me the red over-heat light came on... anywho... let the car cool down... and try to start it again with the A/C on full blast and noting... the fans arent spinning anymore... i try to check fuses and nothing... fans never turned on again... any-who we limped the car home that way... and this morning... i warm up the engine and put the A/C on full blast and the fans work... wierd... what can this be? All fuses are okay i even went ahead and cleaned her battery terminals and replaced almost all of them with aftermarket fuses... Can this be the coolant sensor? if so were is it located... is there also a relay that should be changed... thanks...

just her fans arent coming on anymore... atleast not after she has driven it for awhile... this problem was in the past but it went away and now its
back... NO ERROR CODES OR ANYTHING....

 

[prudence]

same troubles

I had my thremostsate preplaced today, at my mechanics request,paid him $100 dollars. 15 min.later I overheat again
No fans and overheating. All the way home the fans were fine. Everytime I take my car in to the shop the fans work all day for them.

Sorry not to help, but I thought to piggies back on your problem rater than start my own.

Prudence

 

[prudence]

more problems

Out of curosity, i just went and turned her on to see what she would do. fans worked, but no headlights.

 

[hannaco]

It sounds like you have the electrical gremlin.
If the fans work with the A/C turned on, and do not work otherwise, the thermo switch may be at fault. A all too common problem. The result is overheating because the fans do not come on.
The thermo switch is located in the bottom of the radiator. A quick test is to unplug the wire harness from the switch, and use a wire to bridge the pins. If the fans start to spin, then your switch is most likely bad.

Other causes can be the fan control module. Also a loose wire connector that goes to the thermo switch, the fan control module, or the fans themselves.

Look at the fuse box on top of the battery. Look under that fuse box, and see if anything has melted. Sometimes the fuse will look good, but the wire underneath will be bad.

Just remember, you can turn on the heater to cool the motor.

 

[supercharged_v6]

okay... i replaced the freaking fan-thermal-sensor, located on the lower driver side of the radiator... and the fans still arent switching on... i have tried jumping the cables before i replaced it and yes the fans did come on... any other sensor i should replace or look at... thanks.. i need to know.. thanks agian..

 

[hannaco]

Now, you have me puzzled.
The reason I ask this question is because I am guilty of doing this. Are you sure you plugged the fan connector back into the thermo switch? I was so happy that I got the thing back in before getting soaked with coolant, I forgot to put the plug back.
By jumping the plug you proved that the fans are working. They are controlled by two things. The thermo switch for heat control, and the fan control module. The fan control module is controlled by the A/C switch.
If you turn on the A/C, do the fans start to spin?
It is possible you got a bad thermo switch out of the box. Very unlikely.

Lets assume that the thermo switch is good. After the motor is all warmed up, feel the upper and lower radiator hoses. Are both hot? Is the radiator nice and warm from side to side, and top to bottom? If the thermo switch is not getting hot, the fans will not turn on.
Possible causes would be bad thermostat or bad water pump.

Where are you located? Know anyone with a Vag-Com? It would be good to know the coolant temp.


Edit to clean up fat fingered mistakes.

 

[supercharged_v6]

well... i have replaced the thermo-switch sensor and the coolant temperature sensor on the upper radiator hose... i think it was blue but the new one is green... anywho... yes the fans do start to spin when the A/C is on full blast but then the car starts to warm up and the OVER-HEAT light comes on... and the fans wont come on after that... I think the FAN CONTROL MODULE is to blame... But i dont know anyone with a VAG-COM system and the dealer charges a pretty penny... I think ima just give in and replace the FAN CONTROL MODULE... If not then off to the dealer... any other guesses...

 

[skimble]

Have you checked for coolant flow?

Any idea if/when the water pump has been replaced? A '99 surely has enough miles to have killed the OE pump. Mine died at 60k, and I know many others have, too. I had similar symptoms when my water pump impeller cracked at the shaft and was able to spin a little bit, but not nearly enough. A quick way to check if you've got good flow is to turn on the heater (no A/C) and see if you get hot air from the vent. You can also feel the upper radiator hose for heat and pressure, and there's an easy way to inspect the water pump on the 2.0.

With a cold engine, remove the thermostat housing and thermostat. You should be able to feel and partially see the water pump impeller to the left side of the thermostat housing. If you see chunks of black plastic, or can move the impeller with your finger, it's dead. Do yourself (and your girlfriend) a huge favor, and use an aftermarket, all-metal water pump. Also, go ahead and change the timing belt and associated parts at the same time, since you have to go through it to get to the pump.

BTW, if this is the problem, the reason you're seeing what appears to be electrical problems is due to poor (or no) coolant flow not getting heat to the fan switch before the engine temp sensor starts flashing that scary red icon at you. Hope this helps.

 

[skimble]

Testing the radiator fan thermo switch

Here's the short version:
There are two types of connectors on the switch; Type A (square) and Type B (triangle). Regardless of type, disconnect, then use a piece of wire to jump the connections to manually make the fans come on. I attached the two plug gifs, which show the pin assignments, and by using the instructions below, you can do the test.

However, if you've got a dead water pump, this test won't mean anything, because the coolant flowing over the switch in the radiator will never get hot enough for the switch to spin up the fans. Additionally, MY1999 has a separate A/C cut-out Thermal switch that sits adjacent to the coolant temp sensor you replaced, which leads me to believe that this sub-system may be responsible for the fans coming on when you turn on the A/C, then kicking back off when the coolant temp gets too high.

Again, I really think you should check the water pump before throwing any more parts at the problem. IIRC, the radiator fan thermo switch is almost as much as a new water pump...
________________________________________________________________
From the Bentley CD:

Test procedure

- Remove 3-pin connector from radiator fan thermo switch -F18-.


Connector type A

- Bridge contacts -1- and -2- using jumper from VAG1594 A or VW 1594 test kit:

Connector type B

Stage 1 for radiator fan -V7- and -V35- must start to run.
- Switch ignition ON.
- Bridge contacts -2- and -3- using jumper from VAG1594 A or VW 1594 test kit.
Stage 2 for radiator fan -V7- and -V35- must start to run.

--------------------------------------------------------------------------------

19-24

If stage 1 or 2 of radiator fan does not run:

- Use Wiring Diagram for troubleshooting and repair:

Electrical Wiring Diagrams, Troubleshooting & Component Locations
If wiring is OK:

- Replace radiator fan -V7- or -V35- as required.
______________________________________________________________

 

[supercharged_v6]

Thanks...

I do believe now that the problem is the water pump... i mean the upper hose is hot.. and lower hose is cool and so is the lower part of the radiator... i am gonna break down and replace the pump and belt... thanks i will keep you guys upto date... thanks again for the diagrams and procedures...

 

[skimble]

Sounds like a plan. I noticed you didn't say you'd replaced the thermostat, which could be the problem, too. Just for fun, you might pop out the thermostat and see what happens. While you're at it, you can do that water pump inspection I mentioned earlier. If you end up doing the timing belt / pump dance, get an all-metal pump, and all of the associated parts to do it right (stretch bolts, belt tensioner, new coolant, etc).

BTW, Prudence, if you paid $100 just to have a thermostat replaced, you got majorly hosed. That's a $10 part at most, and $90 for literally 10 minutes of labor (plus tax, of course). My WIFE could change the thermostat on a 2.0 in 15 minutes, and I'd make sure she used a torque wrench!

 

[dididothat]

I had the exact same problem. I replaced the coolant sensor, thermoswitch, and thermostat and the fans still wouldn't come on (unless I turned the AC on). It turned out the thermoswitch was not sensing the hot coolant. I could hold a lighter to the switch and the fans would cycle on and off. I dumped a quart of super radiator cleaner into the radiator and left it there for 2 days. Flushed it out and filled with the controversial universal coolant. That solved the problem -- no more cooling problems. The fans cycle on and off properly. It turned out the radiator had clogged and was not circulating properly around the thermoswitch. Shortly afterwards I replaced the timing belt and pump. The pump was still good (after 107,000 miles with the original plastic impeller).

Hope this helps.

 

[supercharged_v6]

hmmm... so let me see... the thermostat is on the driver side right... its that thing with the sensors... on the upper radiator hose? right..??? this engine is so wierd.... but anywho... thanks... i will take off the thermostat and see if thats the problem... but i already have the ECS ULTIMATE TIMING KIT on its way... but it still wouldnt hurt...

 

[Porkchop]

hmmm... so let me see... the thermostat is on the driver side right... its that thing with the sensors... on the upper radiator hose? right..??? this engine is so wierd.... but anywho... thanks... i will take off the thermostat and see if thats the problem... but i already have the ECS ULTIMATE TIMING KIT on its way... but it still wouldnt hurt...

Thermostat is on the lower passenger side of the engine... where the lower radiator hose is. What you're looking at is the coolant flange (a.k.a. heart valve) which just distributes coolant from the upper radiator hose.. that's where the main temp sensor is too.

 

[moose]

Have you checked the fuses ontop of the battery? when my cooling fan crapped out last year. I ended up spending 1300$ on all kinds of repairs when it was simply a fuse. Thankfully someone here suggested what I am telling you and my local VW stealership paid me back in full for the unneeded work that they had done.

 

[supercharged_v6]

trust me... the fuses were the first thing i checked... i checked out all of them... but i believe its either the thermostat or the water pump has just crapped out...

 

[skimble]

but i already have the ECS ULTIMATE TIMING KIT on its way... but it still wouldnt hurt...

IIRC, may be the "Ultimate", but the kit lackes the four one-time-use stretch bolts required to re-attach the engine mount, so you might want to order those, too.

 

[supercharged_v6]

okay it turned out to be a faulty thermostat but oh well... i have already replaced the water pump and timing belt... now i have another problem.. there is a tremendous loss of power when u smash on the pedal... it takes forever and now it just doesnt go fast anymore.. what can this be... i used the ALLDATA TIMING BELTS book as a guide... thanks again.

 

[skimble]

Glad you got it fixed. Who knows, you might still be with your girlfriend when the water pump takes a dump in 60-80k, and you can be a hero again.

 

[STDave]

Sounds like your gears got off when you were changing the timing belt. It sounds like it is limp mode.
David