Golf IV / Jetta IV :: Overheating - Fans Not Coming On
Aug 10, 2014
As the title says, car is overheating. Car gets to 190F within a couple miles drive. Temperature fluctuates between 190F and 225F.
Water pump was replaced ~2 months ago. Was not overheating prior. Temp reached 190F and stayed. Currently has the "black top" coolant temp sensor.
I noticed the coolant fans are not running after I turn the ignition off. This time of year they would usually be running after turning the engine off. If car is overheated and with AC off the fans do not run while engine is running.
I used the guide below to try diagnosing the cause: [URL] ....
Remember both fans should come on in slow speed any time the key is on and the AC is on - if the temperature is above about 32 F (0 C). Both fans run with key on and AC on
S180 (fuse 8, 30 amps, green plastic, above battery) must be good for slow speed operation.
Fuse and holder look good: no melting, no discoloration.
S164 (fuse 3, 40 amps, metal strip, above battery) must be good for fast speed operation.
fuse looks good: unbroken.
To ensure the AC circuits and the Fan Control Module has power check:
Fuse 5 on the cabin fuse panel.
Fuse 16 on the cabin fuse panel. When this fuse is blown the radiator fans will often run unexpectedly.
Fuse 25 on the cabin fuse panel.
All three fuses look good: unbroken
For the first test of the slow speed fans from the radiator thermoswitch have the key off.....Both fans should run in slow speed.
Passed test: both fans run slow
The second test is for the fast speed fans, key on, AC off.... Both fans should run in fast speed.
Passed test: both fans run fast
If the fans run in the tests above, then you should be good to go. No further tests are needed.
If you have been seeing high coolant temperatures and the fans have not been running, then you may need a new thermoswitch.
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So my friend, ignoring my advice that this generation seems to be riddled with electrical problems, decided to purchase a seemingly nice 99 Jetta, with a junkyard AEG swapped in(AEG is written on the intake and block like a JY would do). Sun roof doesn't slide back, gets jammed, evidence shows water has built up previously and run down the A-Pillar to the fuse box.
I just got the fans unplugged and verified that the fans with power applied, both have their low/high speeds. The fuses on top of the battery are in-tact, no visible melting, looks like the thing is in ok shape(haven't taken them off to inspect the contacts yet).
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So i have a 2002 1.8t that i got in december. Everything has been great so far untill the other day the car overheated on me in traffic. It was a bit warm out maybe 75-80 degrees. I saw the needle start to climb and then the light went on so i through the heat on full blast and it dropped the needle a bit and turned the light off long enough to pull off the highway. I let it cool down and checked things out. I am not low on fluid, an the fluid was changed within the last year with the vw recommended stuff. The radiator hoses are pressurized so i believe that the pump and thermostat are working. I am thinking it could have something to do with my fans. I tested them in my driveway by supplying them with 12v and the spun perfectly. It only happens when the car is standing still for a period of time. Driving at any speed is fine. Is there some sort of switch that tells the fans to turn on?
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I have a 2004 volkswagen jetta, and it has started overheating. At first my problem was the thermostat. After that was changed out the fans stopped working correctly. It kept blowing fuses in s180 slot.
I read somewhere in another post that this is due to the fact the resistor in the low speed fan go bad, and for your car's radiator fan to go from zero to high speed, causes the fuse to blow. Also I read that when the fans start up it draws the most current, and then after it's running the current is considerably less.
This is my solution, I went to napa, and got a circuit breaker for a car, and Yes, to my surprise they make them. I picked up several a 10amp, 15 amp, 20 amp, and a 30 amp. First, I tried the 30 amp circuit breaker and it didn't trip the circuit, but when I put a regular fuse in the slot, it did trip the circuit, when I did the fan test at the thermostat switch. Next, I put the 25 amp in there and neither did it trip the circuit. When I put the 10 amp in the s180 slot, it tripped the circuit, just as the regular 30 amp fuses do. So that confirmed that the amps that were being drawn from the fans were not enough to trip a 30 amp circuit breaker.
What I did next, is I took a 20 amp circuit breaker and put that in the s180 slot. Then I hooked up vag com on my laptop to check and see how it performed with the 20 amp circuit, and these are the results.
Car Temperature in celsius
at 111 degrees the gauge was moving past the halfway point
at 115 degrees the gauge was one notch past halfway going towards the red zone
at 120 degrees the gauge was two notches past halfway going towards the red zone
at 122 degrees the fans kicked on high speed for about 30 seconds, and knocked the
temperature down to 105 degrees.
In conclusion, if the high speed on the fans work, you don't have to take those out and go and buy an expensive new fan set. Just stick a 20 amp circuit breaker in the slot, and keep using the fans that you have.
Part no: 782-3154................ Name: Circuit Breaker, 20 Amp; Blade
Note: I take NO responsibility for any damage you do to your vehicle from any information you obtained from this post. Do this at your own risk! I am not a mechanical expert but this is my solution to the overheating problems.
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I don't understand what is going on I noticed smoke coming from my fans radiator fans and I'm pretty sure that it was motor being fried I've gone to the junkyard and bought a used assembly hooked it up and still nothing could be a possibility that when the motor fried it fried the control module for the fans
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I have a V8 engine, and I have been getting the coolant overheating warning come on once in a while.
The engine fans go crazy, and the temperature needle on the small round gauge climbs all the way to red then the coolant overheating warning comes on in dash screen.
This can happen right after I turn the car on, or on occasion, it can happen as I am driving around the city.
I stop, switch the car off, and I turn it back on after a minute, and the car is just fine. So, basically, it doesn't seem like the engine coolant is actually overheating, but the fans and warning systems seem to think that they are. The fans are pretty loud, and its noticeable when they go on, and when this happens, I know that the needle will go all the way up and the warning will go off. I also know that if I turn the car off for a minute, and it will be just fine.
The conditions are random for when this happens. So its not when its particularly hot or cold or anything predictable. Could this just be a sticky thermostat? Is it a bad water pump? Bad battery?
The trouble is that now I am afraid I cant take a real drive. Around the city I can just pull over, but I am afraid to take the car two hours out or something.
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2005 Dodge Neon SXT 206XXX
Long story short on a trip (about a 1 hr. drive) got about a block away from destination and gauge showed it was over heating. Stopped the car started up after five min. just fine. Got home replaced the thermostat and cap (old cap was junk). New cap was junk aftermarket so yesterday I took the same car on a half hour drive to get a Mopar cap ran just fine up again until a block away, pulled off the road turned it off let it set a few min. then didn't even show it was over heating. Let the pressure off and replaced the cap and added in a bit more coolant ran fine all the way back (even pushed speed in a few spots).
The above is just what seems to be the mechanical side of the issue. After noticing the gauge was going a bit above the normal spot I noticed my cooling fans are not coming on. Checked fuse and tested relays out to be fine. First thought is to check voltage to the fans but also tempted to check coolant temp sensor with bench test. Will be going over to my dads to do voltage testing later today.
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So I noticed my temp gauge was starting to rise when I was on the freeway. I figured my fans were out but I just opened my hood and both fans were spinning. When I turned the car off both fans turned off but the temp gauge was almost into the red.
In the morning I turned on my AC and only the passenger side fan was working.
So I am not really sure what my next diagnostic step should be. The engine was not radiating any heat so I am not sure that it is even actually running that hot. Could it possibly be the temperature gauge? If I got a vagcom would I be able to check the actual temperature from there?
I am also concerned on how to find out if the fans are running at both speeds at the appropriate times.
Not sure if this is related but my cruise control stopped working a few weeks ago also.
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I have an 04 gti 1.8t and last night it started over heating. I pulled over and checked the coolant and the oil but everything looked good. I let it cool down and drove it home. When I popped the hood there was a little steam coming from the coolant overflow tank but I saw no leaking. I decided to vent the pressure off the system and then I got a little drip on the passenger side close to where the inter cooler is. I can't pinpoint the leak though.
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As it was such a matter of time, my fans on my 24v gave up during winter, no big deal as it was a pretty cold winter but now that spring is around the corner, I gotta fix this issue. To they change for the same OEM unit that will die in the next 30k miles.
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I have a 1.6 8v mk4 Golf, and my fans started staying on all the time. There are 2 coolant sensors on this model, one is the green one, and the other is the black one which seems to be hardwired into the thermostat housing. Anyway, I changed the green one, and that didn't solve it, so changed the whole thermostat, which obviously came with a new sensor build on....Hey, it worked, for 2 weeks, and then the fans started coming on again as soon as you turned the ignition key...and the temp needle doesn't move much, as before.
My suspicions have moved to the sensor wiring loom, that was fiddled with, while changing the thermostat...I hear they can become brittle over time, and so behave as if the sensor is unplugged, i guess.... Do these wires unplug anywhere in there so I can test the loom properly?
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Compressor does not engage, and my fans do not come on when I turn on the A/C. They do come on low speed when I jumper pins 1 and 2 on the temp switch plug, but they do not come on high speed when I jumper pins 2 and 3.
I have replaced the FCM with a new one, as well as a guaranteed working used one; neither one changed anything. I assumed right away that it was the fcm because my original one has a hole eaten through it from battery acid.
Compressor clutch ohms out within spec, and it will engage if jumpered.
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So I just got a 2002 1.8t, everything was fine until the fans and ac stopped working. After poking around the forums a bit I changed the following:
1. Fan Control Module. Result: nothing
2. Radiator Cooling Fan Switch Temperature Sensor. Result: nothing.
all fan components have the correct voltage going to them. Fuse 16 for the AC clutch is not blown and has power going to it. The AC compressor has power going to it. The fuses on the battery box have power going to them specifically S180.
My question is what am I missing? is it possible that the fans themselves could be bad? car is not overheating, the after run coolant pump kicks on. But the AC clutch is not spinning nor are the fans. btw AC clutch is not seized up.
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I have a quick question, I got a 2005 mk4 gli, and when the cooling fans go on, only one works, the other one does not, I checked the fuse and its fine.
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I went out to my car this morning and the fans were both running full speed. That's before I even got to it then they carried on doing so when I started the car and still ran after I shut it off. I have stopped them by pulling the 30A battery top fuse for them but what has caused it and how I can fix it? Preferably not too expensively as I am moving house next month typically.
The car is a 2003 1.8t GTI with climatronics ....
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A few days ago I was driving around. I get back in my car and when i turn it on no air blows and the radiator fans aren't working at all. My car hasn't overheated but have stopped driving until I can figure the issue out. I have since replaced the fuse box on top of the battery to no avail. I was thinking that it could possibly be the fan control module but in all the posts I am reading not one says that theirs don't work, they just keep running. So is there something else i should be looking at?
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I'm having an issue with my fans on my radiator. They don't turn on when the engine gets warm and the A/C is off. I've replaced the crack pipe, water pump, and belt tensioner. I've replaced the fans not to long ago because the low speed wasn't working. I tested low speed at the fan connector and it wasn't working. After replacing fans I tested and it was working when jumping the pins on the thermo switch connector. I got both low and high speeds to work during that test. I've since replaced the thermo switch to see if it would fix the issue but the fans still won't come on without turning the A/C on. Any other tests I could do or should I just try to get another thermo switch.
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My 03 Golf ac is not working and i am looking for a wiring diagram/ troubleshooting chart. the cooling fans turn on low and I hear the engine surging like the compressor is trying to cycle but it is not.. When I jump the low pressure switch the fans go to high and no power to the compressor. I get a flash of power to the compressor but just a blip every ten seconds. I am trying to check continuity of the ac clutch but having a difficult time getting in there hot. I just bought the car and fixed light body damage on the right front but it was not even bad enough to hurt the washer bottle. Hard to believe the hit caused damage to the ac? AC seems to be charged with about 100 psi static pressure. Why are diagrams so hard to find?
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