98 Beetle: Fan/fuse problem - what's the REAL problem?

[12thmonkey]

We have a 98 Beetle, and twice in the last month the "overheat" light has come on, even though coolants levels are fine.

Had someone look at it, and the fuse for the fan was blown. I've read other comments about this model, and it seems there is perhaps an electrical problem related to this.

Is this fixable? What do I need to know in order to make it right, and is it going to cost me an arm and a leg?

thx

[boschmann]

Are you saying one or both of the 30 Amp fuses by the battery bracket or the fuses under the dash were blown?

[12thmonkey]

Originally Posted by boschmann

Are you saying one or both of the 30 Amp fuses by the battery bracket or the fuses under the dash were blown?

The only one that blew (fried actually) was a fuse by the battery bracket.

[boschmann]

It could be a number of causes, most likely is a cooling fan problem. Try spinning each fan to see if one is binding. You can also look at the thermal switch connector located on the lower left of the radiator. Something caused it to pull too many Amps. Have you replaced the fuse?

[12thmonkey]

Originally Posted by boschmann

It could be a number of causes, most likely is a cooling fan problem. Try spinning each fan to see if one is binding. You can also look at the thermal switch connector located on the lower left of the radiator. Something caused it to pull too many Amps. Have you replaced the fuse?

Yep, replaced the fuse and it seems to be working. I'll check the spin of the fan to see if there's a blockage of some sort.

If I "look at the thermal switch connector located on the lower left of the radiator", what should I be looking for?

thx

[boschmann]

Signs of overheating, burnt or melted wiring, corrosion....

[bleedvw]

i have seen and repaired many of these. you may need to replace the fuse holder on the battery also.
install normal sealed fuses too not the open topped volkswagen fuses

[dirpnirptik]

I have a similar problem currently, but it's a little more complicated.

That fuse was blown, the one by the battery box. It was killing my radiator fans and my temperature sensor was fried. The car didn't get a temperature signal at all, so it always threw the low coolant/high temp light right off the bat. Replaced the fuse, and the Temp sensor...problem slightly better. Now at least the car knew how fast it was actually overheating...meaning that light came on *slower* now...but it was still overheating on me. Did some hunting.
A housing on the right side of the engine was cracked, and leaking coolant and steam all over the place. Replaced that, coolant system works slightly better. There are no coolant leaks. Car still overheating, though.

Now, here's the REAL killer: The car is overheating because it is not properly using the radiator to cool the system. It's getting bad signals. My radiator fan works...one of them...but ONLY IF the AC is on at the time. If my AC is off, the fans never start in the first place. I thought it was because one of them was stuck, bad wire, etc....not the case. The wire is transmitting signals just fine when you pass a current through it...moreover, If you jump a signal straight to the radiator fan, bypassing the original signal source, the fan comes on....not stuck or damaged...just not coming on.
Okay..So I run the AC, sortof like a manual turn-on-my-fan switch.
Stop at a light. Car starts to heat up. NOW when the car starts to warm up to the "hey, we're getting hot now" temperature...the radiator fans turn *off*.

Yeah. Weird, eh? Here's the recap:

Conditions What should happen What does happen
-----------------------------------------------------------------------
Start Car, No AC No Fan No Fan
Warm Car, No AC Trigger Small Fan No Fan
Hot Car, No AC Trigger Large Fan No Fan
Overheating, No AC Trigger Both Fans No Fan

Start Car, AC One Fan Small Fan
Warm Car, AC Trigger Small Fan Small Fan
Hot Car, AC Trigger Large Fan *Kills Fan*
Overheating, AC Trigger Both Fans *Fan still dead*


Now, I've been told there's a Fan/AC ECU module that can short, and cause this sort of issue. It is either a 14 or a 10 pin connector, depending on what was available the day they built the car...it's the Coolant fan control module. After some wiring diagram meditation, I've pinned down a few conclusions:

#1: This ECU is connected to the AC thermal cut-out switch.
#2: This ECU is connected to the fuse that *melted* itself in the battery box
#3: This ECU controlls which of the Fans comes on.


Now: Has anyone else encountered this problem, and if so, am I runnin off the wrong end of logic here? My theory is that replacing the 14 pin Coolant fan control module is going to ensure the proper electrical demons get excersized before my car blows up at every red light. (Problem complicated by my residence in the middle of the Arizona desert.)

Cause I really dont wanna have to run it off a bridge.

[veedubmechanic]

The problem on theese are the fuse/relay bracket on top of the battery. Replace it with a new one. Also the fan control module under the battery tray (located upside down) also are a common problem on 98-2001 vehicles especially 2.0