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I have a 2003 VW Jetta 2.0 and my fans won't turn on and…

Customer Question
I have a 2003...

I have a 2003 VW Jetta 2.0 and my fans won't turn on and there's no power to the ac compressor as well. I've replaced the thermo switch, radiator, thermostat, ac pressure switch, top battery fuse box, checked all fuses, replaced new fans, replaces FCM, tested AC Compressor by applying 12v directly and it engages, when removing fuse #5 both funs runs in low speed. I simply cannot find the issue and can't drive the car otherwise it would over heat w/ no fans working.

Mechanic's Assistant: Is the power loss consistent, or does it fluctuate?

What do you mean?

Mechanic's Assistant: What confuses you?

Fans simply won't turn on

Mechanic's Assistant: Are you fixing your Jetta yourself? What have you tried so far?

Yes I have a 2003 VW Jetta 2.0 and my fans won't turn on and there's no power to the ac compressor as well. I've replaced the thermo switch, radiator, thermostat, ac pressure switch, top battery fuse box, checked all fuses, replaced new fans, replaces FCM, tested AC Compressor by applying 12v directly and it engages, when removing fuse #5 both funs runs in low speed. I simply cannot find the issue and can't drive the car otherwise it would over heat w/ no fans working.

Submitted: 5 years ago.Category: VW
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Answered in 2 hours by:
6/5/2017
VW Mechanic: kyle swart,
 replied 5 years ago
kyle swart
Category: VW
Satisfied Customers: 1,456
Experience: Certified Technician at Redding Volkswagen
Verified

Hello, my name is ***** ***** thank you for using just answer. First, I would like to separate the fan systems that this car has, since you have already done quite a bit of work. The car turns the fans on in a couple different ways. There is a thermal switch in the radiator that turns them on when the engine exceeds normal operating temperature, then turns back off once it is cooled down to a certain point. Anytime you turn on the a/c (even with the engine off, but key on) the fans should run on low speed. there is 2 safety overrides, there is a second switch inside the thermal switch in the radiator for high speed fans if the low speed fans arent doing the job. The ecm can also trigger high speed fans if it see's the coolant temp sensor is too hot. If you have a way of monitoring the temperature via a thermal gun, or scan tool, i would let the engine idle and monitor the temperature. If low speed fans do not come on and the engine gets to 100 degrees Celsius with no fans, we will address that first. If the low speed fans do cycle with temperature, but do not work when you turn the a/c on, then we will address that. Also, please let me know if this is a manual heat/ac system or climatronic, and what transmission the car has, ( standard, auto, or tiptronic) Let me know, thank you.

Kyle S.
A.S.E. certified master auto technician
licensed smog technician, test and repair, L-1 advanced engine performance certified
Certified Volkswagen technician, 2003,2004,2013,2014,2015
Volkswagen and Audi independent 12 years

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Customer reply replied 5 years ago
Hello Kyle, Thank you for your reply. Yes, I've replaced the thermo switch that goes on the radiator. When I turn the key to the ON position and turn on the AC (button) either fan are not engaging at all. I have a 2003 VW Jetta 2.0 Automatic, w/ Climatronic AC I even turn the engine ON and made sure I'm not on ECON mode on the climatronic, waited for car to get it to 190 degrees F but fan still does not engage. I used VCDS from Ross tech to check temperature and the temperature goes from 87 to 90 degrees Celsius which I think its normal, that's like 190 degrees Fahrenheit which is how its supposed to be unless I'm wrong. Either fan still doesn't engage. I checked for codes and there are not fault codes. Like I said when I put 12v directly to the ac compressor it kicks on, I even checked the fans, I disconnected the thermo switch and jump the connector and both fans run on low speed and high speed. If there's no fault code for the ECM, can the ECM still be malfunction? Will replacing the ECM fix this issue? I'm out of ideas NOW! I don't know what to do anymore? I disconnected the big connector (4 thick wires I think) from the FCM and jump them and both fans runs on low and high speed. I even replaced the big black wire the goes to the AC compressor and alternator. When I checked w/ a multimeter the AC compressor connector there's no voltage at all. Finally I replaced the coolant temp sensor as well.
VW Mechanic: kyle swart,
 replied 5 years ago

Thank you for that information. So, if you let the engine run, with the a/c off, will the engine start to overheat or will the fans come on? you need to let it run past 98 degrees celcius. If it wont, you may have a stuck open thermostat. You may also have to raise rpm to get it hot enough. I just want to know if those fans will come on with the thermal switch. That part of the system is all hardwired, the ecm and a/c has no control over it.

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Customer reply replied 5 years ago
Ok, so I let the engine run w/ the a/c off even if I try to turn it on it won't because there's simply no power to the a/c compressor and after letting the engine run for a while and pass the 98 degrees celsius the car doesn't overheat I mean the temp needle only moves a little bit past the 190 degrees fahrenheit but the fan will not engage at all. I already replaced the thermostat for a new one as well. This is very strange, I'v searched everywhere and it seems that no one has encounter this type of issue, most just say its the fuse box because the fan (green) fuse melted and after replacing the fuse box it fixed the issue. Mine is completely different. I tested the connectors for the thermo switch and it works so it must be something else.
VW Mechanic: kyle swart,
 replied 5 years ago

The only other thing I have seen that has caused a similar issue, is the the coolant temp sensor had failed to the point that coolant was getting inside the electrical connector, then the coolant wicked all the way to the engine computer and soaked that too.

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Customer reply replied 5 years ago
This makes no sense. Ok, so I tried posting another question but it says its the same question even though its for a different car. Same year and and model though, could this also be the ECM as well? 2003 VW Jetta 2.0 Automatic w/ Manual A/C there's also no power to the A/C compressor, I've replace the FCM, fans, coolant temp sensor, thermo switch, A/C pressure switch, applied 12v directly to the compressor and it works, blows cold air the only different issue w/ this car is that both fans engages no matter if the A/C is off or engine is cold and keeps running for 10-15 mins. When turning the car to the on position the fans immediately start to run, both fans in low speed, I even replaced the resistor that's under the glovebox. Engine doesn't overheat, I know this sounds funny but one of my car's fan doesn't work at all while the other keeps running after turning the engine off. I replaced all the same stuff that I replaced on my other Jetta. I did everything that I did on the other Jetta and I can't find a solution to either of my Jettas.
VW Mechanic: kyle swart,
 replied 5 years ago

Bolth fans are supposed to run together whenever the fans are commanded on. With the key on, engine off, if the a/c is on, both fans should come on even with the engine off.

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Customer reply replied 5 years ago
but both fans comes on when a/c button is off and engine is cold. I know that both fans should come on even if the keys is switch to the on position and a/c is on but this is not the case, as soon as the key is removed from the ignition and engine is cold fans should be off but instead they keep running.
VW Mechanic: kyle swart,
 replied 5 years ago

Do you have a scan tool capable of reading value blocks in the engine computer?

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Customer reply replied 5 years ago
I'm using VCDS and I do see an option for "value blocks"
VW Mechanic: kyle swart,
 replied 5 years ago

Ive tried to help you as much as possible, but i think this one is just too hard to diagnose via forum communication. Im going to opt out and let others assist you.

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VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago
Wolfgang
Wolfgang, VW Master Technician
Category: VW
Satisfied Customers: 6,718
Experience: Senior VW Master Tech 15 yrs
Verified

Thanks for choosing Just Answer . I'm Wolfgang here to help!!

I am confident we can resolve your problem together. Please
understand that I don't know your skill level. In most cases when you have a problem
with the way the vehicle performs, specialized tooling is required to acquire computer
data/information or engine testing results. We didn’t build these complicated vehicles; we
just diagnose and fix them. Also understand that I can't see, smell, hear, or touch the
vehicle either, so it may take a few replies to get to satisfactory results. Note there may be an issue where the complexity of the issue will require a Premium Service. This service will be an addition to the normal question cost. Usually it does not come down to this but keep in mind!! I am also going to direct you with the fastest, easiest and most common things to check first. Please be
patient and permit me to do what I do best.
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
through it.
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail.

ok first thing vcds will not help you on this issue. you will need a voltmeter to check this out .

I do need a vin # of the vehicle to get the factory information.

was the vehicle involved in a front end collision?

please do let me know!!

Thanks

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Customer reply replied 5 years ago
Hi Wolfgang,
Here's the VIN of my of vehicle 3VWSK69M33M158116 No front end collision whatsoever and besides VCDS I also used a multimeter to see if there's any present volts on the A/C compressor connector and there's any power to when either when the engine is off or on. Where else do I check for power w/ the multimeter? Thanks
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

i need you to check fuse #5 and make sure you have 12 volts at both sides of the fuse with the fuse still installed car running.

if that is on then on the fan control module measure voltage with the connector still in the fan control module pin 9 of the 14 pin connector .

let me know

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Customer reply replied 5 years ago
Ok, so I checked Fuse #5 and both ends have 12v when car is running. I will check pin 9 of the 14 pin connection from the FCM later today and let your know the results. Thanks.
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

ok got it!!

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Customer reply replied 5 years ago
I checked and double checked Fuse #5 again, and also Pin 9 of the 14 Pin from FCM while connected w/ key in the ON position and also w/ car running. When switching key to ON Position I get 12v on fuse #5 and Pin 9 of the 14 Pin and when engine is running I get 13-14v on both Fuse #5 and Pin 9 of 14 Pin. What's the next step? Thanks
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

i was trying to get back with you on this but you opted me out !!!

with the key on do you have power pin 4 to ground and pin 5 to ground of the 14 pin connector?

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Customer reply replied 5 years ago
Hi, sorry. I thought you opted out like the previous technician since I hadn't heard from you for a few days that's why I went ahead and asked for anther technician. I will check for PIN 4 & 5 of the 14 PIN and let you know if there's power w/ the key ON. Thanks again.
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

yep!!

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Customer reply replied 5 years ago
I checked for voltage on PIN 4 & 5 and theres no voltage present.
Customer reply replied 5 years ago
I haven't heard from you. What should I test next? Thanks.
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

ok fuse 16 of the fuse panel is the fuse good?

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Customer reply replied 5 years ago
fuse 16 from panel is ok. 12v when car is off and 13v when on.
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago
You need to unwrap the wiring of the FCM to find the break in the wire.
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Customer reply replied 5 years ago
Does this mean unwrap everything all the way to the fuse panel?
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago
No but in the area of the fan control module and from the radiator switch down. I have seen splices go bad.
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Customer reply replied 5 years ago
Ok, so I unwrapped the wiring of the FCM and everything is intact. Is there another step I should considered? At this point I'm considering replacing the whole FCM wiring but it seems like a lot of work so is there another way of testing each wire or something? Also I try posting another question but it says its the same question so it gets cancel. I have the exact same car, 03 VW Jetta 2.0 GL w/ manual A/C, this is funny because on this car the fans stays ON all the time even when car is cold, as soon as I turn the key to the ON position the fans starts to kick in even when the engine is cold and they run for about 15 mins, no power to A/C compressor also so A/C doesn't work at all, I've replaced everything just like my other 03 Jetta we're discussing here.
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

ok the ambient temp switch at the cowl area under the black cover . i need you to check if you have voltage at one of the terminals

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Customer reply replied 5 years ago
there's voltage, a 4v on the connector.
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

do you have continuity at the switch itself?

and what is the voltage at pin 14 to ground of the FMC when the connector is plugged in ?

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Customer reply replied 5 years ago
How do I test continuity at the switch itself? disconnect the switch and connect probes to it or? or test wiring connectors? does PIN 14 goes to one of the terminals of the ambient temp switch? I'm still getting 4 volts
VW Mechanic: Wolfgang, VW Master Technician replied 5 years ago

measure the switch at the 2 terminals of the switch make sure that the resistance is less than 2 ohms.

so pin 14 has 4 volts correct?

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