Check your radiator/condenser fan operation NOW

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
You verify that you have the right amount of refrigerant. It is installed by weight. The only way to be sure is to remove the charge, then insert the proper weight.

Then verify the clutch is working.
Then check system pressures. If the high pressure is too low, and the low pressure is too high, the compressor is not pumping OR the Thermal Expansion valve is stuck wide open. It is essentially impossible to tell the difference in these two failures, which is why most professionals always replace the TXV and the compressor, and the drier.

You can also verify that your filter drier is not plugged up by checking the temperature of the pipe before it and after it. The temperature should be the same. If it is cold and sweating downstream of the drier, then the drier is plugged up. If the drier is plugged up (on the Mk IV) then you would have normal suction pressure and low high pressure (since the high pressure gauge is hooked up downstream of the drier.)
 

aslspiderman

Veteran Member
Joined
Jan 9, 2011
Location
Lexington NC
TDI
98 Jetta
This is a fantastic thread!!! Thanks DanG144. I pulled the drivers side fan and found a brush stuck because of crude. Cleaned it out, put it back together and viola! it works again. For those who do not have a dremel tool, I was able to bend the tabs back with a chisel and hammer. It worked very well and I was able to bend the tabs back the same way.

Dan, I'm trying to understand your terminology. Your mention the "filter dryer", is that the same thing as the "receiver dryer" in the bentley book? Checking the receiver dryer, it feels warm on both sides. It also has a Parker/Hannifin sticker on it, so I'm assuming that it is not original equipment. the Damper and piping on both sides are cold and sweating with the a/c on. I now have both fans working and I can see the compressor clutch is engaged when the a/c is turned on in the car.

Is there anything else that I can do without proper gauges and special tools. Or is it time to take it in and have it professionally checked? Thanks for all your help.

Found the problem--bad fan took me in the wrong direction. Turns out it was the flapper in the dash was stuck on the heat side. So I did have two problems, the fan being one. The other being much less expensive than a compressor.
 
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DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Post 607. Guess I will jump in too. I had a Fan Control Module fail to activate the clutch on AC and reverse engineered it to see why it failed. If anyone wants to send me their old FCM I will add it to my failed pile and IF it gets repaired, send it back to you. I get the knowledge of various failure modes and you get the chance that it will be repaired as a spare. Sorry, no returns unless I am successful with yours. And please don't wait for a prompt return if fixed. This is an experiment like our early work on the MAF sensors. It is not a business (yet).

I am thinking of adding a circuit that will PWM the high speed motor connections in place of the series resistor low speed circuit. To slow the motor with the resistor places a lot of heat in the motor and is probably responsible for the brush holder melting we all experience. The MKV PWMs the low fan speed so why not the MKIVs?

PM me if you have one to donate. I will send you the forensic results when I get to it.

Charlie
In fact someone in the UK is selling a PWM module (one for each fan, I think) that did work well. It was expensive, and slow to arrive. I know one guy that put one in and ran it for years - until his car was totaled.

Since the slow speed fan is designed to work from either the FCM or from the radiator thermoswitch, I think it would have to at least be a unit separate from the FCM, but I do not see why one PWM unit could not function for both fans.

Now, if someone could just get rid of the pesky brushes in DC motors...

Folks, I know Reference Design. Please send him any failed FCMs; there is a fair chance he can fix it and return it to you. This may help the community here.
 
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Ramseyfish

New member
Joined
Sep 28, 2011
Location
fort lauderdale, fl
TDI
jetta 2001
cooling problem

Dan, hi! You have helped me before and i really appreciate it. I didnt know how to find you without just doing a search in the forums so if there is a better way to reach you please let me know. Sorry for butting into this conversation...

I have a 2001 Gas Jetta with cooling problems.

I have replaced the thermostat but same problem exists.

For the past several months the level in the expansion tank would fluctuate sometimes causing the low level/temp to come on. Occasionally i would add just a little bit of fluid but there were no aparant leaks.

Now, the water starts rising in the tank after you shut off the engine and within 5 min is blowing out the overflow port. The expansion tank eventually POPPED and water would flow around the threads on the cap and the cap didnt fit tight. I replaced the expansion tank and it still over flows.

The temp gauge on the dash NEVER goes over 190. When the engine is cold and after you start it it will rise slowly to 190 then stop like it always has but when you stop it is gurgling under the hood and then eventually spews out.

WHen i had the thermostat out i put my finger in the hole to where i could feel the fins of the pump (something i learned to do online) and tried to turn the pump trying to detect if the impeller was spinning on the shaft but it was solid.

I flushed the whole system and water freely flowed through the radiator.

I am baffled.

another jetta owner friend suggested that maybe some of the fins have broken off. Or maybe the radiator is not fully cooling even though water flows through it.

Why would the temp never go over 190? WHen the engine has been running and i stop and leave the engine running the water in the tank is fluctuating rhythmically up and down by about a 1/2 inch. But when you shut off the engine it will eventually over flow.

Any thoughts? I really appreciate it.

Mark (if you want to email me instead markcoleman1964@gmail.com)
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
You can Private Message people by simply clicking on their name, in my case that would give you my email address as well.

The behavior you describe is due to exceeding the temperature at which your system boils, down in the guts of the engine.

You have done a good job of checking your water pump, it is probably ok. But be warned that the grip of the water pump to its shaft can lessen as the coolant temperature rises. It circulates fine at low temperatures, but starts spinning on the shaft at higher temperatures. Check for flow through the small vent line at the top of the reservoir when idling after a highway drive. It should look the same as when you first start the car up.

The dash gauge reads 190 straight up and down until you exceed 225F. When it first deflects from the 190 position by the tiniest amount you are already at 225F. So you can be operating at 224.9 and never know it, unless you use a scangauge or VCDS system to check. You can also use the VCDS system to compare the Engine control temperature sensor to the Instrument panel temperature sensor.

Do you take this car on highway trips of over 30 minutes with no overheating issues?

You have not indicated that you have checked the fan operation. One cause of the condition you describe can be the fact that the whole radiator is full of hot water because the fans are not working.

When you shut it down the local hot spots in the engine raise the local temperature and you get boiling, which causes the expansion into the tank you see. When the steam void collapses the tank level drops.

A second potential cause is corrosion at the junction of the cooling fans and tubes. I had this happen to my 1977 Chevy LUV which started its life in Hawaii. The salt water caused corrosion which was not visible under the radiators paint. But when I brushed it with my fingers the rust at the junction became obvious. This also lets the temperature get too high, so you are always close to boiling in the engine. The bottom of the radiator is at essentially engine temperature instead of being cooled.

Normally the cool water (it is cooled to ambient temperature) from the bottom of the radiator will naturally circulate through the engine as the thermostat opens upon shutdown. This in conjunction with the fact that the engine is still 20 degrees or more from boiling to start with prevents the behavior you describe.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Everyone PLEASE check your fans are working routinely.
They don't last forever.

Do not run for long with only one fan working. The Refrigerant compressor runs too hot and cooks the Refrigerant Control Valve. Then the compressor stops running.

Just check the fans and keep them running - avoid costly and time consuming repairs. The fan is $100 or so. The compressor replacement is probably $1200 or more at most shops.
 

bigolac

Well-known member
Joined
Mar 11, 2012
Location
Wisconsin
TDI
99 Beetle
Dan - Thank you so much for your reminder - we just purchased our first TDI - a 99 Beetle about two months ago. I would turn the ignition on, turn on the ac, and nothing. When I fired the engine, I would get the fans to run at fast speed for a few seconds and quit (the AC does blow cold air). I read through your A4 Coolant Fan Testing pdf, and look what I found for the first item to look at:



Needless to say - I cleaned up the contacts, and now both fans work properly in slow speed with the ignition on.
Again - Thanks to you and so many in this community that will help preserve my TDI for many miles to come!
- Adam
 

steffen707

Veteran Member
Joined
Dec 7, 2005
Location
Central Wisconsin
TDI
01 Jetta GLS TDI
Are the fans suppose to run after you shut the car off?

My tdi I just picked up is doing this, and I don't mean for like 3 minutes, but for a lot longer than that.

I know i've got a loose wire or something by the fan control module, but I'm confused why a loose wire would tell the fan to keep running. Wouldn't a loose wire cause it to shut off in a fail situation?
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Steffen, check your fuses. I inadvertently pulled an A/C fuse as a temporary replacement for fuse 14, and when I did the fans continued to run. Just checked my Bentley and I think it could be fuse # 16 because I needed a 10 mini fuse so I could lock the car and set the alarm.
 
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steffen707

Veteran Member
Joined
Dec 7, 2005
Location
Central Wisconsin
TDI
01 Jetta GLS TDI
It depends upon which wire is loose.

The fans should not run on when the car is off.
Any ideas what wire would cause this?

I checked fused s164, s180, s5, s16 and s25, all are in tact, and not blown. I havn't checked for power on both sides of the fuses yet, i'm going to tackle that tonight.

I also found the sweet "coolant fan control module j293 pinout table" that explains what each of the 14 wires going to the Fan Control Module do.

So my fans keep running and the A/C won't turn on. I shut the car off, took the key out of the ignition and opened the hood. I want to trace where the radiator fan wires go to and I heard a clicking of a relay. I grabbed ahold of the wires and the fans turned off, I let go of the wires and the fans turned on again. I grabbed the wires again and the fans turned off. REPEAT......

Well obviously one is loose, coroded, shorting or something. I don't think its the fan control module itself because its when i move the wires that it turns the fans on/off.

Thoughts?
 

cparagone

Well-known member
Joined
Apr 22, 2012
Location
amston, ct
TDI
2005.5 jetta 2002 Golf GLS
DanG144,

Thank you, thank you, thank you!!!

just started religiously reading the forum about a month ago when my 2005.5 jetta tdi needed the camshaft replaced and found a great mechanic: 94x and we got the parts from franko6 dealership wanted 6600 for the job and were to replace the whole cylinder head, unnecessarily. 94x pointed out DMF noise, looked into it and replaced that, and to get to the point while i have been under the hood more myself i notice the two radiator condenser fans were not coming on.....

so today with your great advice/how to's i pulled the fans out opened the fan housing and found that 3 out of 4 brushes of the 2 fans were hung up and not making contact. cleaned everything up, put it back together and tested it out, BAM both fans work!!!! Love it!!! thanks again

 

Lurchalicious

Veteran Member
Joined
Mar 10, 2008
Location
KY
TDI
02 Jetta TDI
A thank you for the reminder from myself, driver's side fan was dead and after just having my wife's whole A/C system replaced along with a new set of fans I ventured into this.

Interesting note I found out from replacing my fans, went to my local ORiley auto because they price match autozone. Autozone had the doorman brand fan assembly for 128.99, oriley was 239.99 and I wanted to see if they would match.

Not only did they match but since autozone was offering a limited lifetime on the doorman and they only offered a 3mo warranty on the same unit, they sold me a VDO unit because the warranties matched. Their list price on the VDO unit was over $400 - all at the price of 128.99

Not too shabby
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
Dan,

I tested my car today AC switch on / ignition on ( motor not running ) both fans came on. Good to go. This is a great write up.


However on my daughters 2000 Golf 2.0 gasser did the same test any nothing. Then I started the car and after approx. 60 seconds the small fan came on but not the large one. then it cycled on/off about every 2 minutes. My daughter said the large fan hasn't been running when she checked it.
So I dissassembled the large fan an noticed one of the brushes heated up and melted the plastic bracket so I cleaned the melted area up best I could so the brush could slide in/out easily. I reassemble and the fan, and after starting the engine it work along with the smaller one.
When the engine is running the AC clutch never disengaged but the fans contnued to cycle on/off every 2 minutes. Engine cold.
Does a 2.0 Gasser AC operate differently then a TDI???

Thanks
 
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DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Terry,
The 2.0 gasser controls appear identical. There is no reason I can see for cyclic fan operation. Sometimes you see the fans shift to fast in hot weather, but never off.

Do her fans start even with the key on engine off, now, as they should?
 

Lurchalicious

Veteran Member
Joined
Mar 10, 2008
Location
KY
TDI
02 Jetta TDI
How are they supposed to stay in business doing things like this? Volume?


Yuri
No idea - didn't know how they were selling the doorman unit for over 200 when auto zone up the street had it for a hundred less.

now the VDO - i only saw the "list" price on my receipt - looking it up on the website it sells for 280; big difference but hey - Oriley people work on commission, autozone doesn't - so its been in my experiences that the people at Oriley want my business and will compete for it... or perhaps I just had a lucky break.
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
Terry,
The 2.0 gasser controls appear identical. There is no reason I can see for cyclic fan operation. Sometimes you see the fans shift to fast in hot weather, but never off.

Do her fans start even with the key on engine off, now, as they should?
The morning I tested both of our cars it was cool outside. My fans came right on with engine off, and her car did not. Then when we fired up her engine I had her turn her AC on and the fans didn't come on until about 30 seconds then cycled back off in about 90 seconds or so, and then kept cylcing at that interval. All the while the clutch never disengaged.
I think I'm going to replace the large fan. One of the brushes is only about 5/16" long it keeps getting hung up in the bracket.

She is up at USC taking a Maymester, if you get a good opportunity one weekend I'll run up there and we can bring it by if you don't mind looking at the GASSER.:rolleyes:

BTW her AC is colder than any car I've been in.

Edit: I'm curious what the fans do once the car has been running for a good while??
 
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DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
For you Terry, I'll look at a gasser.

It sounds to me as if only her fast speed fans are working, neither slow speed fan. We can check it out. The AC will work fine. The compressor will be working at higher than normal pressures and temperatures, and so its life will be shortened.
 

schoolcb

Active member
Joined
Sep 27, 2011
Location
Mid Cities area of TX
TDI
2006 Jetta TDI
Thanks for the post, fixed one of my fans this weekend, piece of cake with your pics. My fan setup was a little different, but it was a brush hanging up in the holder that caused the fan to stop working.

Why isn't this original post in the FAQ/DIY section???? :confused:
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
For you Terry, I'll look at a gasser.

It sounds to me as if only her fast speed fans are working, neither slow speed fan. We can check it out. The AC will work fine. The compressor will be working at higher than normal pressures and temperatures, and so its life will be shortened.
Thank you Dan that's awsome of you. I know you hate the smell of
gas.:p

I will do the slow speed test before I bring it over and see what I come up with. I probably won't get a chance to run it by for a few weeks. But I'll try to do the test this Sunday afternnon if possible on my way through.
 
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mwalters

Veteran Member
Joined
Nov 10, 2003
Location
SE Michigan - Have VCDS
TDI
Jetta TDI 2013 Tornado Red
Thanks for this thread, guys! My A/C quit blowing cold air the other day and searched and found this thread. Seems my driver's side fan has broken the plastic "hub" away from the motor shaft. It sound like the motor runs, but the fan just sits there all loose and floppy. I ordered a Doorman replacement unit for about $90 shipped - should arrive tomorrow. I'll get that fan replaced and then see what else is screwed up.
 

MIGHTYDAD

Active member
Joined
Mar 5, 2007
Location
COLUMBUS, KANSAS
TDI
NEW BEETLE TDI 2000
I have a 2000 new beetle TDI 1.9
I turned my key on (not the motor) and turn my AC and the fan on low. The AC button lit up, but the cooling fans did not come on, neither one. Could this be why my AC isn't working?
 

Johhny04

Veteran Member
Joined
Feb 21, 2006
Location
Markham, Ontario
TDI
2003 Jetta TDi
Glad I stumbled upon this thread. Driver side fan not working after following simple test. Seems seized when trying to rotate the blades. Picking up a new one today. Hopefully didn't stress the A/C system that much this season. Also checked my brother car and his is fine. Thanks for a great thread DanG144!
 

FordGuy100

Veteran Member
Joined
Apr 13, 2011
Location
Silverton, OR
TDI
2004 Jetta TDI
Ordered two large fans for both of our cars....both of the large fans fail the test. Auxillery fans work great though!
 

TDI_G

Veteran Member
Joined
Dec 16, 2011
Location
Sugar Hill, Georgia
TDI
None Currently- 2008 BMW 335I
Checked my fans last night and sure enough the fan on the driver's side is not working. I spun the fan by hand and it wasn't exactly smooth to say the least. I am picking up a new fan after work today and will replace it tonight. Glad I found it now as I have a 1,600 mile round trip coming up in a few weeks.
 

passinpumps

Member
Joined
Mar 22, 2005
TDI
Jetta, 2001,Red
A/C worked for 10 minutes after New FCM

I have an ongoing wicked problem with the A/C in my 2001 TDI Jetta with manual controls. I had no cooling fans and no A/C. Went through the diagnostic. Found that I had a bad driver side fan and replaced it. Both fans then worked when tested from the radiator sensor, but would not turn on with ignition on A/C + fan switch turned on.

Replaced FCM. Cooling fans worked and A/C turned on and worked for 10 minutes and quit. Vent temps were about 65 Degrees F. Measured from low side with cheap fill gauge while it worked (DID NOT ADD ANY REFRIGERANT) and pressure was about 35. Outside Temp was around 90 Degrees F. Then the cooling fans quit and A/C compressor shut down.

Cooling fans now turn appropriately when doing the test from the radiator sensor (and engage with Fuse 16 pulled), but neither the compressor nor the fans engage with ignition switch on or engine running.

What is the most likely cause? G65 Sensor reads duty cycle 31.6% @ about 92 Degrees outside temp. (I assume that the engine compartment is about 110 degrees).
 
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