Check your radiator/condenser fan operation NOW

RayBrubaker

Active member
Joined
Jan 4, 2001
Location
Waxhaw, NC USA
Working on a 99.5 A4 Jetta ALH, Replaced a blown-up AC high/low pressure switch and charged the system. Compressor clutch engages but the fans don't come on. All fuses are good. Checked fans per the beginning of this thread and they work on low and high when jumping at the radiator temp sensor plug. Before I buy a FCU I want to confirm my diagnosis. The FCU is working partially since it turns on the compressor and the high speed fan (when jumpered). Is it likely that one mode of the FCU would fail? I've tried different searches on this thread but haven't found exactly this situation. Thanks for your help.
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
HI,

Checked my fans today and they work .... whew ... I could not remember hearing then run.

Good thread to make sure stuff is ready when it starts getting hot.

Thanks!
 

gusechopper

New member
Joined
Jul 15, 2014
Location
alabama
TDI
2000 jetta
The t14/6 pin has less then .5 when the engine is off and 58+ when the engine is off. i can not find a break in the line. any one have an idea on what i should look at next?
 

jelmerfud

New member
Joined
Jun 3, 2020
Location
Minneapolis
TDI
2003 Mk4 Jetta
AC Problem Mk4 Jetta

I am a brand-newbie to the TDIclub forum, and have appreciated the tips and the help in this thread about A/C issues.
I have a 2003 Mk4 Jetta and the A/C is not working this spring (It has worked flawlessly up until this season).
It is a manual control climate system, and the AC button illuminates and the cabin fan works - it is blowing warm air, however. It sounds like the engine RPM dips when the AC button is engaged, but I could not hear the compressor engage.
Thinking it just needed a shot of refrigerant, I tried that first. I quickly found that the pressure in the AC system was very high - due to the fact that the compressor was NOT running.
I tried the radiator and condenser fan test from the beginning of this thread. I found that ONLY the large fan on the driver's side worked in slow speed with the key ON and the AC button ON. The Passenger side fan did not run. It does seem to spin freely by hand.
I checked the fuses over the battery, and everything looks good - fuses are good, and no sign of melting or corroded terminals or contacts.
I am at a loss for what to try next. I am looking to tap the community expertise here - Would the FCM be the most likely culprit? Would it be the fan itself? I can't see where replacing the fan would make the AC suddenly engage and start to work (?).
I have not tested the wire leads at the passenger fan to see if it is getting power. That is my next planned step. If it IS getting power, then I have to assume that the passenger side fan motor burned up - but why would that keep the AC from running if the large drivers side fan works?
Grateful for any thoughts or advice you can bestow upon this frustrated newbie. Thanks !!
 

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
If only one fan turns, then you need to replace both fans. I say both fans because when one fails, the other is usually ready to fail, gets knocked around when changing the bad fan, and has been working harder to compensate for the failed fan. Also the fans are wired together, so both should always run together.

Pressure does not mean the system is charged enough. My guess is that the system pressure got too high with only one fan running and may have vented some Freon. Possibly not enough Freon left for the system to start up.

I would get new fans (like IDParts sells) installed, then find a shop to recover and recharge the system. That way you can find out how much Freon is really in the system. If it still doesn't work, come back and ask questions. There are some good HVAC people who can help.

Jason
 

ymz

Top Post Dawg
Joined
May 12, 2003
Location
Between Toronto & Montreal
TDI
2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
If only one fan turns, then you need to replace both fans. I say both fans because when one fails, the other is usually ready to fail
One of our cars had the 2nd fan fail 3 months after the first... the other cars only had the one go bad... the other fan kept going for years... (over 200,000 miles... and still going...) YMMV...



Y.
 

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
One of our cars had the 2nd fan fail 3 months after the first... the other cars only had the one go bad... the other fan kept going for years... (over 200,000 miles... and still going...) YMMV...



Y.
And I can't count how many times I sold a customer the one fan that failed, only to have the other fan not work after the repair. Labor cost money to pay someone and its the same for one fan or two.

Now if you do it your self it becomes a question of how much do you value your time? I have two little kids and have no extra time to be taking the fans out more than once. So I get OEM and do both so it's one and done. If' you're single or just have plenty of free time, then take them out, take the motor apart, and fix the brushes.

Jason

BTW - older A3 Jettas only have one motor and a belt drives the other fan. Not sure if B4 Passat is the same.
 

Boondoggle

Active member
Joined
Jun 8, 2011
Location
Roberts, WI
TDI
2006 Jetta TDI Manual, 2002 Jetta TDI Automatic, 2002 Jetta TDI 5 speed manual swap, 2002 Beetle TDI Manual
I have a 2002 Beetle TDI and the AC is not working, and when I turn on the key, and press the AC button, neither radiator fan is running. It is 80F. I checked the fuses above the battery, and the fuses appear good. what is the next thing I need to check to diagnose this problem.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
I have a 2002 Beetle TDI and the AC is not working, and when I turn on the key, and press the AC button, neither radiator fan is running. It is 80F. I checked the fuses above the battery, and the fuses appear good. what is the next thing I need to check to diagnose this problem.
Start reading back at Post #1. All your answers are here. Dan did a very thorough job with this, contains much more than just the fan bidness.
 

colemanp2

New member
Joined
Jul 4, 2020
Location
Pennsylvania
TDI
2004 jetta tdi
Fan problem

Question if 1 fan is bad will it keep both fans from starting in low speed pr should i look deeper like the fan control relay also
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2014 Tiguan,2003 Jetta 261K Sold but not forgotten
Follow the "Check your radiator/condenser fan operation NOW" thread in the top of the forum list.

If it's electrically dead I would think the other should work.
They both get power together.
They both ground to the same point.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Question if 1 fan is bad will it keep both fans from starting in low speed pr should i look deeper like the fan control relay also
Start reading back at Post #1. All your answers are here. Dan did a very thorough job with this, contains much more than just the fan bidness.
 

Rabbijalabbi

Member
Joined
Jul 6, 2020
Location
Ypsilanti, MI
TDI
2002 Jetta sedan, F250 Super Duty 6.4L
AC problems

Ok, so I started at the beginning of this thread, but I have not read through the entire thing...
I have '02 Jetta TDI and AC compressor clutch is not engaging. Started trouble-shooting fan electrical system, and found that when key is turned on, and AC button is pressed with fan turned on, radiator fans do not operate at low speed. However, when I remove fuse 16 on the inside cabin fuses, they do turn on. Does this tell me where the problem is? Fuse 16 is a 10 amp fuse that is good. I traded it out with other working fuses to make sure.
 
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Rabbijalabbi

Member
Joined
Jul 6, 2020
Location
Ypsilanti, MI
TDI
2002 Jetta sedan, F250 Super Duty 6.4L
ok, so I connected 12v directly to ac compressor and it does not engage clutch...I believe this tells me I have a bad compressor, correct?
 

jayb79

Veteran Member
Joined
May 20, 2000
Location
Exeter,NH
Bad clutch coil to be specific.
This part is fairly simple to change, the coil can be found on ebay for less than $20.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
ok, so I connected 12v directly to ac compressor and it does not engage clutch...I believe this tells me I have a bad compressor, correct?
Did you connect a known good ground too?
Yes I did...I made sure I was connected to a good ground... I knew it was working because wire got hot real fast that I was connecting with
Hmmm - what size wire were you using to do this test? The clutch should only draw 3-4 amps and will make a very audible metal to metal "smack" sound when the coil is powered. Unless you were using a 24 gauge wire, it shouldn't get hot for this test.
 

branhamd

Member
Joined
Jul 20, 2020
Location
washington
TDI
99' 1.9 TDI Golf
I have a 99' 1.9 tdi golf that I recently got and am new to the Volkswagen world and the car has ac but the ac button wasn't lighting up so I figured I would tear into it and try and troubleshoot it and see if there was power coming to it. I now have the whole dash torn apart and am frustrated because there are a harness of wires coming to the ack of the climate controll knobs. What's the best way to approach the ac button not lighting up. The recirculate knob does light up. I am assuming if that isn't lit up I dont have a complete circuit. Sorry about all the questions I'm learning on the go.
 

carl20320

Well-known member
Joined
Feb 15, 2020
Location
SW WA
TDI
2004 Mk4 Golf GLS TDI 5spd
Noticed my large fan was not turning properly the other day. Son drove it last weekend and came back asking what was making all the noise. Checked and sure enough, the fan went belly up. Today, bought a new fan and started removing the old one. Will have to remove the skid plate and it was already time for dinner so the install will wait until tomorrow morning. Having Cascade German a short drive away is really helpful in situations like this.
 

ctxj90

Member
Joined
Apr 15, 2014
Location
Newtown CT
TDI
98 jetta TDI
I have an 05 BEW, and my AC wasn't working. I figured the pressure was low. I vacuumed the system and put a partial charge in, couldn't get the compressor to run, but the small fan would spin. When I unplugged the FCM and plugged it back in, I developed a new problem. Now the small fan stayed on even with the key off and out.

I tried to spin the large fan by hand, it was clearly dead. So I ordered a fan and a module. Put them in and now BOTH fans run as soon as the key is turned, and continue to run with the key out. I unplugged the temp switch and they still run constantly. I have checked all of the fuses in the door panel and they all were in good shape. The fuse box on top of the battery is newer and shows no signs of discoloration. Not sure where to go next with this, any help would be greatly appreciated.
 
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runningallday

Well-known member
Joined
Jul 22, 2017
Location
Iowa City, IA
TDI
1999.5 Jetta TDI manual
just wanted to say, thanks for reminding me to check my fans. my big one quit. swapped it out (~$40 for a new one from amazon) and I got two working fans now! :D only took 15 minutes to swap it out too, super fast!
 
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