Overheating no fans

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
Have 2003 Jetta 1.9 A4 TDI, over heating issue,
I've run the following test's,
http://forums.tdiclub.com/showthread.php?t=242699
http://pics.tdiclub.com/data/516/A4_Coolant_Fan_testing_Rev_7.pdf
All fuses, in cab & over battery good, I did have a bad Fuse 16 on the cabin fuse panel and the radiator fans would often run unexpectedly. Replaced fuse, drove and still overheated when climbing, no fans still.
NOTES,
Lost the charge on the freon due leak in condenser 2 weeks ago.
There was a note on the above test that the fans would be locked out if there isn't and adequate charge in the a/c system.

Question, does this means no fans at all if a/c is in-op/low charge or the fans will still engage if the radiator thermo switch closes calling for fans to run?

Thanks,

Nick
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
fan control module, i think on the mk4 its under the coolant ball like on the mk3. dont go cheap on this part.
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Asheville, NC
TDI
2002 jetta Wagon
No, he to a picture of the fan control under the battery.
If you turn the AC on the fans should run. If not then either the control is bad, the wiring is bad, or the fan is. Test continuity across the fans and post those readings.

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Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Not necessarily. If there's no pressure in the system the fans will not come on with the button in.

But -- the thermoswitch on the radiator will still work.
 

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
I've tried all the previous tests as to not to waist your time and I appreciate each of your responses. This has been an on going issue for a month.
The vehicle will not over heat while driving on normal surface road's. Both fans do work with 12v when following test procedures and checking for 12v to radiator temp switch harness. Also have 12 v. in all harnesses while following test procedures. Fan Module is new, VW engine temp switch is new, the radiator temp switch function's on bench test/stove boiling water, I'm getting pins 1&3 to show continuity at boiling point, which I believe is fans are on high, and fans should come on if the circulation gets to radiator temp switch while driving (I've been running with fans wired hot/high just to commute, but when I head up the 4 mile hill to get to the house it overheat's about 3/4's of the way up blowing all the coolant out of the surge tank, which causes a low coolant alarm to go off, and I pull over and ad more coolant each time. No other loss of coolant in the cooling system can be found. I did replace the T-stat early on and tested the old one and it opened as designed at 192 F. I do have a heavy stream of coolant into surge tank at 2K RPM & at idle, which I'm thinking the h2o pump is good and it felt intact when I replaced the t-stat. Could this possibly be a circulation issues not letting the radiator circulate properly and not letting the temp switch tell the fans to come on?
Any help or suggestions are appreciated?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Just to clarify:

If you disconnect the thermo-sensor on the lower part of the radiator (near the fan controller), with the key on you should be able to use a jumper wire on that connector and make both LOW and HIGH speeds come on, by simply jumping two wires (I forget which colors, but there are only three, so it only takes 10 seconds of trial/error to make that work, and you are only bridging one half of the circuit, so no danger of shorting anything).

If that works, but the engine is still overheating, and you have the coolant pump working as indicated by the flow in the bottle, then it sound like you have some sort of clogging in the radiator itself. This is rare on that car, but possible if foreign coolant was used and caused a sludging issue.
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Asheville, NC
TDI
2002 jetta Wagon
At this point, if you haven't, I would simply replace the temp sensors.
In the end it may not fix the issue, however, they need replaced occasionally.

The next thing is to be sure there's no breaks, or leaks, in the system!
The coolant system must be pressurized or it'll overheat! The pressure causes the coolant to boil at a higher temperature. So if the coolant ball is cracked, or there is a small hole in a hose, if the EGR cooler has a crack, you will have issues.

My thought is that I would replace the sensors to get the new control module to work properly and hopefully control the fans better, not too expensive. Then I would figure out how to pressure test the system to find any leaks possible.

My last question is when was the coolant/timing belt, done last? Is the coolant good? Usually we avoid coolant issues due to timing belt changes.

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gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI
One other thing... make sure you are actually have coolant flowing through the radiator. The fans will hardly ever come on under normal circumstances. When the thermostat failed in my 03, it would run a bit hot with no fans. I thought the thermoswitch was bad, but realized that the radiator never got hot. Simply turning on the heat was enough to keep the engine cool in 90+ degree weather.

Apparently the thermostat had been bad for a while but it never got warm enough to notice.

Once the thermostat was replaced, the car ran cool enough to never need the fans. My 04 is the same - unless the AC is on, the fans never cycle.
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Not to be a Debbie Downer...... how many miles on car?
I had a similar issue on my 01 golf, I was at about 388,xxx miles on my car and started to blow coolant on a hard drive up a hill or just laying into it for fun, had the same symptoms.
I run with a scan gauge all the time and noticed that I was climbing in temps when doing long up hills to the point I was blowing coolant out the bowl.
After trial and error I found that if I drove like an old lady temps could be manageable till I had time to trouble shoot it.

Long story short are you sure it’s not the head gasket ?
This was the issue on my car, hows the coolant color? And color of the bowl?
Just a thought.
 

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
OH, yes both hi & low fans work with jumper wire.
Ed, I have an OEM temp sensor on order, I did put in a new after mkt just to check it, and after it warmed and ran for 30 min with rpm, I had temps (with heat gun) at the upper radiator hose housing & left side of the radiator at 200+, right side was 170-180 at the top, I removed the fan harness from the tempswitch to check fan operation again and noticed the plastic housing of the tempswitch would spin (no longer tight in the brass) this happened twice (2 different sensors), I'm not sure if the temps were to high and melted the inners or just a POS after mkt, after I removed each of them they still spin and the parts guy said thats not right. I've put the original back in for now, with no luck.
Ed, I have been high and low inside & out and dont see any leaks except what over flows the surge tank and runs down the frame. Also, the system does hold pressure, hoses swell tight, and still has some pressure the next day when I remove cap.
How do you inspect the EGR cooler for cracks/leak?
Timing belt/coolant was done 12K ago, and with that being said I was told to use a fleet guard (red) due temps, but since then I've done some more research and switched to Zerex G40 (pink) for VW's, I did not drain the fluids when I switched products, can the mixing of those two cause issues?
Gforce, I've replaced the t-stat with new 192 with no change. Whats the best procedure to check for correct flow? Hoses & inner housings look very clean, no rust or crud!
Does anyone know what temp the tempswitch calls for fans?
Also, how does the radiator coolant flow threw the radiator?
I wanted to check for good flow and drained the radiator, put garden hose nozzle in upper hose with a clamp to hold nozzle in hose, with lower hose removed, turned on water and it instantly ran out the lower outlet, I expected the water to take a few seconds to flow across the radiator and feel the radiator cool, but that was not the case, it just runs out the bottom hose connection and isn't being forced to run across the cores? To me, if the normal coolant circulation is taking the same path, the 200+ coolant should be triggering the fans as it runs down to the lower hose???
Thanks for the responses!
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Does the coolant temp sensor value show the engine is indeed getting hot? The scan tool data as well as the gauge?

Maybe it is more of a pressure issue than a temp issue, and maybe a bad cap is the cause.
 

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
OH, yes both hi & low fans work with jumper wire.
Ed, I have an OEM temp sensor on order, I did put in a new after mkt just to check it, and after it warmed and ran for 30 min with rpm, I had temps (with heat gun) at the upper radiator hose housing & left side of the radiator at 200+, right side was 170-180 at the top, I removed the fan harness from the tempswitch to check fan operation again and noticed the plastic housing of the tempswitch would spin (no longer tight in the brass) this happened twice (2 different sensors), I'm not sure if the temps were to high and melted the inners or just a POS after mkt, after I removed each of them they still spin and the parts guy said thats not right. I've put the original back in for now, with no luck.
Ed, I have been high and low inside & out and dont see any leaks except what over flows the surge tank and runs down the frame. Also, the system does hold pressure, hoses swell tight, and still has some pressure the next day when I remove cap.
How do you inspect the EGR cooler for cracks/leak?
Timing belt/coolant was done 12K ago, and with that being said I was told to use a fleet guard (red) due temps, but since then I've done some more research and switched to Zerex G40 (pink) for VW's, I did not drain the fluids when I switched products, can the mixing of those two cause issues?
Gforce, I've replaced the t-stat with new 192 with no change. Whats the best procedure to check for correct flow? Hoses & inner housings look very clean, no rust or crud!
Does anyone know what temp the tempswitch calls for fans?
Also, how does the radiator coolant flow threw the radiator?
I wanted to check for good flow and drained the radiator, put garden hose nozzle in upper hose with a clamp to hold nozzle in hose, with lower hose removed, turned on water and it instantly ran out the lower outlet, I expected the water to take a few seconds to flow across the radiator and feel the radiator cool, but that was not the case, it just runs out the bottom hose connection and isn't being forced to run across the cores? To me, if the normal coolant circulation is taking the same path, the 200+ coolant should be triggering the fans as it runs down to the lower hose???
Thanks for the responses!

Sorry, timing belt kit, head gasket, done 30k ago not 12K, had a bad glow plug that just spun and wouldn't come out and dropped a piece into the cylinder while trying to remove. Car currently has 180K
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
I’m leaning toward a head gasket......
Where did you get a replacement head?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
I’m leaning toward a head gasket......
Where did you get a replacement head?
 

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
Not to be a Debbie Downer...... how many miles on car?
I had a similar issue on my 01 golf, I was at about 388,xxx miles on my car and started to blow coolant on a hard drive up a hill or just laying into it for fun, had the same symptoms.
I run with a scan gauge all the time and noticed that I was climbing in temps when doing long up hills to the point I was blowing coolant out the bowl.
After trial and error I found that if I drove like an old lady temps could be manageable till I had time to trouble shoot it.

Long story short are you sure it’s not the head gasket ?
This was the issue on my car, hows the coolant color? And color of the bowl?
Just a thought.
Coolant color good, no water in oil or vise versa in surge tank, how did yours look when your gasket went south? any other was to check for bad gasket?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
After doing mine twice I’ve switched to using arp studs now......
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
Does the coolant temp sensor value show the engine is indeed getting hot? The scan tool data as well as the gauge?
Maybe it is more of a pressure issue than a temp issue, and maybe a bad cap is the cause.
when I get the low coolant alarm, and inspect under the hood, water is boiling in surge tank/over flowing, and can hear it in the head as well. Turned heater on and let idle, bleed pressure and refill. I did swap the cap with another used one with no change, I guess I can order a new one, but how do you test?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
The color of my coolant slowly became darker as well as the coolant bowl.
I also didn’t have any oil in my coolant .
I did not pressure check my system as mine didn’t show issues when driving normally, my particular issues was when running slightly hard and on long up hills doing more than the speed limit.
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
again It’s duplicating my posts
 

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
The color of my coolant slowly became darker as well as the coolant bowl.
I also didn’t have any oil in my coolant .
I did not pressure check my system as mine didn’t show issues when driving normally, my particular issues was when running slightly hard and on long up hills doing more than the speed limit.
I did replace the surge tank when this all started, thinking it was cracked due to the small amount of coolant down the frame, which just got worse over time now boiling over, and the original tank was more than likely good.

Is there a good post here or anyone have instruction on how to test for head gasket issues?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Was the head checked for warpage?
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Asheville, NC
TDI
2002 jetta Wagon
Head gasket is checked with a cylinder pressure and leak down tests.
Look them both up.
Harbor freight had a good diesel compression testing tool.

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Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
The color of my coolant slowly became darker as well as the coolant bowl.
I also didn’t have any oil in my coolant .
I did not pressure check my system as mine didn’t show issues when driving normally, my particular issues was when running slightly hard and on long up hills doing more than the speed limit.
Ok just went out and look in surge tank no that its empty and see a film of black oily substance in the bottom, see pic (nevermind) I can get it to load with my message, so head gasket???
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Unless you have a severe leak , the leak down test will not show anything .
It’s when the engine is under a good boost is where the leak presents itself.....at least that was my case....
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Unless you have a severe leak , the leak down test will not show anything .
It’s when the engine is under a good boost is where the leak presents itself.....at least that was my case....
 

Az.Nick

Member
Joined
Mar 25, 2020
Location
AZ
TDI
2003 1.9
Was the head checked for warpage?
Honestly I can't remember had a friend thats had several VW's do most of it, but will reach out and see what all was done. Work was done 30k ago, could this be something that can happen over time or if warped it would be immediate?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
I highly recommend that you get arp studs as they have a better holding power and are reusable.
From now on that’s all I’m gonna use on my cars.
 
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