Check your radiator/condenser fan operation NOW

hevster1

Vendor
Joined
Nov 14, 2005
Location
Columbia NJ
TDI
98 NB
DanG144 said:
hevster,
They came directly from the Bentley manual chart for normal operation.
I, personally usually see more like 25 psig on the low side on my own cars and up to 35 psig on others.

I have tried (not very successfully) to keep this thread on the electrical control side of things. So I gave a simplistic answer to a question that obviously came from a novice at AC work. Perhaps I should have ignored the question.

Knowledgeable folks know that the refrigerant cycle pressures and temperatures vary depending upon the conditions - and how they vary, and why they vary. I refuse to attempt to try to address these issues unless I am in a one on one situation. I simply am not up to the task via a written media.

Now if someone else would attempt a troubleshooting guideline thread on the mechanical side of things...
I thought i did one a while back. I will have to see.
 

scidav87

Veteran Member
Joined
Jul 16, 2009
Location
Kansas City
TDI
2001 Jetta 5-speed 1980 Rabbit 1.5L
Found out more about the car today. I unpluged the FCM an jumped the 1-2 terminals on the Thermoswitch. That is supposed to activate the low speed fans, it didnt'. Instead of 1 wire (low speed wire) being hot, all 3 were at 13 volts and lite the test light brightly at both fans. So, i plugged in the FCM, and same result, all 3 wires had 13 volts, but this time, my interior chime went off, the air bag light, abs, check engine and ac lights were all on, even with the key out of the car, so i put the key in to cycle the ignition, no effect. So, i then started the car, started fine, but when i shut it off, the car stayed running, even with the key out of the car, and all those lights were still on, i had to put the car in gear and pop the clutch to shut it off. Now, with the FCM unpluged, the lights are off and it shuts off fine. Plug it back in and the lights go back on and the car won't turn off. Same thing happens on the road, when the engine gets hot enought to turn the fans on, the fans wont come on and when you try to turn off the car, it stays running. My A/C never works, and the fans never work.
 
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DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
scidav,
This means that your main problem is almost certainly your grounding wires for the clutch, fcm, fans, G65. One common grounding wire path, as mentioned above.

Good luck finding and fixing it.

Please take photos for us to define the grounding locations.

There are grounds underneath the battery box, but on top of the mounting plate. But I do not remember any of them being a 4.0 mm wire. The only large wire I remember seeing there was the huge main ground.
 

SheeB

Veteran Member
Joined
Jul 8, 2007
Location
Ottawa, ON
TDI
2001 Jetta GLS Manual
DanG144 said:
I never hear mine either. Never, unless the AC is on.

Perhaps the fan will fix it.
Well I originally decided to change the left fan, but I am going on previous experiences of only doing 1/2 of the job, and the other 1/2 always seemed to die not long afterwards so I ordered the right side fan as well. ;)

If that does not fix the issue, I will replace the high pressure switch. At least it seems easy to swap out and locally its only about $50 which is not a back breaker :cool:
 

scidav87

Veteran Member
Joined
Jul 16, 2009
Location
Kansas City
TDI
2001 Jetta 5-speed 1980 Rabbit 1.5L
DanG144 said:
scidav,
This means that your main problem is almost certainly your grounding wires for the clutch, fcm, fans, G65. One common grounding wire path, as mentioned above.

Good luck finding and fixing it.

Please take photos for us to define the grounding locations.

There are grounds underneath the battery box, but on top of the mounting plate. But I do not remember any of them being a 4.0 mm wire. The only large wire I remember seeing there was the huge main ground.
The battery was removed, and there was 2 small wires, i think brown, that were grounded right under the battery tray, the ground were fine at that location. I don't see, however, how a bad ground would make the ground wire turn into a positive wire, which all 3 wires at the fans have 13 volts.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
If a ground wire is lifted from its ground, it normally goes to +12v when the first load is turned on. G65 is always turned on with the key, so if you lifted the ground from ground 12, the wire would read +12v anytime the key was on (and maybe even before, through the FCM.) There are many items grounded through ground 12.

I was trying to say earlier, that some grounds were under the battery (on top of the tray), but I did not think they were the ones you were looking for, as they were too small.
Were any of the wires you found 4 mm wires? medium to medium large?

I suspect the wires you are looking for are UNDER the battery mounting tray, under where the battery box bolts in.

But I do not know for sure.

Your best bet to find this is a very close visual inspection. Use a good light, pull the wires out of the loom, cut the protective tape or heat shrink off.

I can only tell you what I would do. There is no guarantee of success.
 

scidav87

Veteran Member
Joined
Jul 16, 2009
Location
Kansas City
TDI
2001 Jetta 5-speed 1980 Rabbit 1.5L
If it makes any difference (I still haven't looked at a diagram :/) All 3 wires are positive, with or without the key on AND with or without the FCM, but with the thermo switched jumped between 1-2. I'll continue to check grounds when the wife gets me the car back again.
 

efb91

Well-known member
Joined
May 16, 2008
Location
NY
TDI
2003 Jetta TDI
There's 9 volts going to the compressor, so it can't be the fan module, and it was that the compressor's shot, like the dealer said. The coolant fan is repaired. The only thing that remains is to drain the coolant and swap out the compressor. My only question is why 9 volts goes to the compressor even if the engine isn't even started? Could someone explain that to me? What the hell trips the clutch then?
 

scidav87

Veteran Member
Joined
Jul 16, 2009
Location
Kansas City
TDI
2001 Jetta 5-speed 1980 Rabbit 1.5L
I would think for sure that if it wasn't grounded it would be just like a loose wire, with neither ground, nor power. In order to have the 12 volts, wouldn't the positive wires and that ground wire have to contact somewhere? Thanks for responding all the time :)
 

efb91

Well-known member
Joined
May 16, 2008
Location
NY
TDI
2003 Jetta TDI
Wow. Look at those post times. Responded in less than a minute. God bless you, Dan. You've really helped a lot of people on this board. You make it worth being in this TDI community.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
efb,
I was not replying to you, but to scidav.

let me go back and read your saga, to see if i can get caught up with you.

I can possibly answer one of your questions off the top. Unless you have some current drain (load, resistor, lamp - even a tiny one) on the clutch circuit many of the FCMs (but not all) will show 9 volts all the time. If you have the clutch (or any other load) hooked up to it, it will drain the voltage to zero. This is because there is some transistor-type component used as a switch and not a hard wired contact. It effectively stops current flow, but with an open circuit it will slowly rise to source voltage. Even a 1 milli-amp drain is probably more than enough.

So when making determinations on clutch circuits, you must always have a load on the FCM. One of the easiest ways is to have the clutch hooked up, and stick safety pins through the wires to measure the voltage. Just paint a little sealant over the hole when you are done.

I learned this the hard way.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
efb,
You have fixed your fan? Both fans now work?

Do they still come on as soon as you turn the key on?

What do they do when you unplug the high pressure refrigerant sensor?

Can you catch us up in your story?
 

Strider199

Veteran Member
Joined
Mar 15, 2010
Location
Canada
TDI
1999 Golf TDI New Body Style
Sorry to interupt on the problem at hand. Since the temperature is getting warm here in Ontario, I decided to read this thread. I tried out the fan check as metioned in the opening. After 10 years the fans both came on silent when the manual A/C button was pushed. Thanks for the info. I've never heard the fans come on before while driving. Always wondered if they even worked. :)
 

scidav87

Veteran Member
Joined
Jul 16, 2009
Location
Kansas City
TDI
2001 Jetta 5-speed 1980 Rabbit 1.5L
Must be nice, apparently my fans haven't been working in the 2 years i've owned my TDI, and the fix is being a P.I.T.A.
 

WhiteBox

New member
Joined
May 27, 2010
Location
Ohio
TDI
Jetta 2002 1.8T
First sorry to bust in since i don't own TDI but i been to dealer service already few times about same problem and every time they just seams like skip over my problem and do zillion other things.

Anyway while ago while trying to get out of traffic after 4th July firework my temp gauge started rising. Kind got worried there for second but just before temp vent into red i was able to get out traffic and hit highway, as soon as i started gaining some speed temp vent down. I think that was like 3 years ago. So ever since every time i vent to service i would complain about that and they would "like" do something but same problem still exist. I drive to work 20 miles after about 10-15 miles driving if i get stuck in traffic where it would be bumper to bumper my temp would start going up.

So i did your little test with push the AC button in, place a fan in slow and leave your key to ON, small fan is truning in what looks like slow speed big fan not at all.
I checked that fuse on top of battery and it seems ok as well the connection where fuse goes in.

AC seems to be working ok, i get enough cold air that will cool down inside in no time.

P.S. i own 2002 Jetta 1.8T and can't wait to pay of that car so i can go get big gun and shot the car.
Thanks,
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
WhiteBox said:
First sorry to bust in since i don't own TDI but i been to dealer service already few times about same problem and every time they just seams like skip over my problem and do zillion other things.

Anyway while ago while trying to get out of traffic after 4th July firework my temp gauge started rising. Kind got worried there for second but just before temp vent into red i was able to get out traffic and hit highway, as soon as i started gaining some speed temp vent down. I think that was like 3 years ago. So ever since every time i vent to service i would complain about that and they would "like" do something but same problem still exist. I drive to work 20 miles after about 10-15 miles driving if i get stuck in traffic where it would be bumper to bumper my temp would start going up.

So i did your little test with push the AC button in, place a fan in slow and leave your key to ON, small fan is truning in what looks like slow speed big fan not at all.
I checked that fuse on top of battery and it seems ok as well the connection where fuse goes in.

AC seems to be working ok, i get enough cold air that will cool down inside in no time.

P.S. i own 2002 Jetta 1.8T and can't wait to pay of that car so i can go get big gun and shot the car.
Thanks,
So you are going to repair or replace the big fan?
 

WhiteBox

New member
Joined
May 27, 2010
Location
Ohio
TDI
Jetta 2002 1.8T
DanG144 said:
So you are going to repair or replace the big fan?
Is there anything else that i can check before i do that just to be sure that something else is not wrong and not the big fan?
 

SheeB

Veteran Member
Joined
Jul 8, 2007
Location
Ottawa, ON
TDI
2001 Jetta GLS Manual
SheeB said:
Well I originally decided to change the left fan, but I am going on previous experiences of only doing 1/2 of the job, and the other 1/2 always seemed to die not long afterwards so I ordered the right side fan as well. ;)

If that does not fix the issue, I will replace the high pressure switch. At least it seems easy to swap out and locally its only about $50 which is not a back breaker :cool:
Well lone behold when I got home the left side fan arrived, still waiting for the right side to arrive Monday. I installed the left side fan in about 1/2 hour with the car on ramps. As soon as I tested the fans with the car not idling, the new fan sounded like a whirlwind compared to the old fan :eek: I could now hear as well that my right side fan is dying too, and does not spin as fast as the new fan. That will be taken care of shortly :)

So I started the car, and the fans initially went to high speed but maybe a minute later kicked down to slow speed :D Seems like I am on the right track here, so I will swap the other fan next week and report back with some new (hopefully final) results.
 

GD

Veteran Member
Joined
Jun 11, 2002
Location
Toronto
TDI
2011 Jetta TDI Highline DSG
Hi,

Anyone know why the power to the Ac compressor pulsates and not provide steady voltage for the clutch to kick in?

The refrigirent is full and both cooling fans cycle when AC switch is on.

I recently replaced the large fan as it seized up and the small fan was replaced due to it operating at one speed. Also replaced the large strip fan fuse on top of the battery.

Thanks
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
GD said:
Hi,

Anyone know why the power to the Ac compressor pulsates and not provide steady voltage for the clutch to kick in?

The refrigirent is full and both cooling fans cycle when AC switch is on.

I recently replaced the large fan as it seized up and the small fan was replaced due to it operating at one speed. Also replaced the large strip fan fuse on top of the battery.

Thanks
When you say the fans cycle, do you mean they start and stop, or change speed? If so check the fuses listed in post #1 in the documents linked. If they are all good, (and the fans do cycle) then this is often caused by a failed pressure transducer.
 

GD

Veteran Member
Joined
Jun 11, 2002
Location
Toronto
TDI
2011 Jetta TDI Highline DSG
DanG144 said:
When you say the fans cycle, do you mean they start and stop, or change speed? If so check the fuses listed in post #1 in the documents linked. If they are all good, (and the fans do cycle) then this is often caused by a failed pressure transducer.
Fans are good they come on together (and stay on) when the AC is switched on but the power to the AC compressor is not constant it comes and goes and not enough for the ac clutch to kick in.

Is the transducer the same as A/C Thrust Sensor 1K0959126B
 
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DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Yes that is the high pressure sensor or transducer for A4 cars after May of 99.

But since the fans are behaving properly, that is not likely to be your problem. If it was bad the fans would be cycling when the voltage to the compressor does.

Are you sure your clutch coil resistance is 4 ohms?
 

GD

Veteran Member
Joined
Jun 11, 2002
Location
Toronto
TDI
2011 Jetta TDI Highline DSG
DanG144 said:
Yes that is the high pressure sensor or transducer for A4 cars after May of 99.

But since the fans are behaving properly, that is not likely to be your problem. If it was bad the fans would be cycling when the voltage to the compressor does.

Are you sure your clutch coil resistance is 4 ohms?
Haven't checked the clutch coil resistance just the voltage to the compressor.

As soon as the AC is switched on both the fans come on at the same speed. But power at the compressor pulsates at the same time.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
I understand that the voltage to your AC clutch is pulsating.

Assuming the fans are operating in slow, not fast, that would seem to rule out the High pressure sensor or thrust sensor.

It could still be the FCM, or the FCM responding to a cutoff signal from the ECU, or a clutch coil that is too low in resistance (shorted) and drawing too much power.

What voltage are you seeing to your compressor? And are you measuring it with the clutch coil hooked up? Or with some other resistive load on the circuit?
 
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