Check your radiator/condenser fan operation NOW
- Thread starter DanG144
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Jettadoor
Veteran Member
A couple of years ago I fixed my AC with help from this excellent post. With a new FCM, coil and driver's side fan it has been working fine ever since. Until, that is, the bearing in the pulley went bad a couple of weeks ago and chewed up the 'brand new' coil.
It would have made good sense for me to replace it at the time, given the age and mileage on the car but it was still "O.K." and I was penny wise and pound foolish. Just something to consider when fixing an older car.
It would have made good sense for me to replace it at the time, given the age and mileage on the car but it was still "O.K." and I was penny wise and pound foolish. Just something to consider when fixing an older car.
Golf2K
Well-known member
2000 Golf TDI 5spd 411,000 kms
All fuses look fine
Manual A/C, was working last summer, and the A/C compressor was put in a few years ago, and the lines look good. This summer no cold air, A/C clutch doesn't engage.
I did the ignition on test with A/C on, interior fan on and the Rad fans do not turn.
I pulled of the 'Thermo Switch' Plug and jumpered 1-2 got the big fan to turn, small fan did not.
I then jumpered 2-3 on same plug, turned on ignition got nothing, tried all A/C and fan settings, fans did not spin
I hooked a battery up to the Big fan connector and it spun on both settings, the battery was weak so it didn't spin too much faster on the full speed setting, which I think is post 2-3 to a battery.
Small fan did not spin when hooked up the battery, I think I tried every which way.
Sounds like I need a New Fan assembly and possibly a Fan Control Module.
Any tips?
All fuses look fine
Manual A/C, was working last summer, and the A/C compressor was put in a few years ago, and the lines look good. This summer no cold air, A/C clutch doesn't engage.
I did the ignition on test with A/C on, interior fan on and the Rad fans do not turn.
I pulled of the 'Thermo Switch' Plug and jumpered 1-2 got the big fan to turn, small fan did not.
I then jumpered 2-3 on same plug, turned on ignition got nothing, tried all A/C and fan settings, fans did not spin
I hooked a battery up to the Big fan connector and it spun on both settings, the battery was weak so it didn't spin too much faster on the full speed setting, which I think is post 2-3 to a battery.
Small fan did not spin when hooked up the battery, I think I tried every which way.
Sounds like I need a New Fan assembly and possibly a Fan Control Module.
Any tips?
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puntmeister
Veteran Member
I'm far from an expert, but you could start with just replacing the small fan (since it doesn't seem to run no matter what). Or, go ahead and take out the back of the small fan - check the brushes/brush holders (mine were melted - you might get lucky, and they're just stuck).
See what happens. The new small fan should obviously run if hooked up directly to power.
In any event, the fans aren't that pricey - probably worth putting a new one in either way.
See what happens. The new small fan should obviously run if hooked up directly to power.
In any event, the fans aren't that pricey - probably worth putting a new one in either way.
Golf2K
Well-known member
Well the small fan doesn't seem serviceable.
If I check the fan with a Ohm meter on post 1-3 nothing, 2-3 get 1.5 Ohms I think. and 1-2 nothing. I think. If I knew how to open the fan I would. I know that 2 settings get nothing and one gets 1.5 Ohms.
You should get a reading on all 3 settings. I'm gonna now check to see if my good fan comes on when the Engine temp is over 92c Degrees.
If I check the fan with a Ohm meter on post 1-3 nothing, 2-3 get 1.5 Ohms I think. and 1-2 nothing. I think. If I knew how to open the fan I would. I know that 2 settings get nothing and one gets 1.5 Ohms.
You should get a reading on all 3 settings. I'm gonna now check to see if my good fan comes on when the Engine temp is over 92c Degrees.
puntmeister
Veteran Member
The fans aren't technically serviceable. However, it is possible to either cut off the little ears on the back plate, or pry it off (carefully) - after opening up and fixing (if possible), then welding back plate back on with JB Weld.
Given the fans aren't terribly expensive, and 'servicing' them is a bit of a headache, and not necessarily terribly reliable, probably all-around easier to just replace.
Given the fans aren't terribly expensive, and 'servicing' them is a bit of a headache, and not necessarily terribly reliable, probably all-around easier to just replace.
seahedge
Member
Problem with my AC
My AC stopped working last week. I noticed my drivers side fan is not working. The passenger side AC fan is. The problem seemed to coincide with the fan starting to stay on after I turned the ignition off and removed the key. It stays on I suppose until the engine cools to a certain point then it shuts off (5 or 10 minutes generally).
I originally thought the freon needed to be charged so I bought a can and hooked it up to the port. The reading was in the red so I did not add any.
I had AC compressor replaced by a garage when it seized up this past January. My friend checked it with a Vagcom but he could not override the system and get the compressor to turn on.
Do you have any ideas on what I should check first? Fuses seem fine.
Thanks,
My AC stopped working last week. I noticed my drivers side fan is not working. The passenger side AC fan is. The problem seemed to coincide with the fan starting to stay on after I turned the ignition off and removed the key. It stays on I suppose until the engine cools to a certain point then it shuts off (5 or 10 minutes generally).
I originally thought the freon needed to be charged so I bought a can and hooked it up to the port. The reading was in the red so I did not add any.
I had AC compressor replaced by a garage when it seized up this past January. My friend checked it with a Vagcom but he could not override the system and get the compressor to turn on.
Do you have any ideas on what I should check first? Fuses seem fine.
Thanks,
puntmeister
Veteran Member
My understanding, if both fans aren't running (and the driver fan is the bigger of the 2...), then the AC runs into trouble (cuz there is insufficient cooling due to inoperable fan).
I have never had my fans stay on after turning the car off - and I live in Arizona....
I have never had my fans stay on after turning the car off - and I live in Arizona....
zukikat
Veteran Member
Based on how I read your explanation, when your ignition is ON, AC button pressed, inside blower switch ON, your fans don't run.
You've checked all related fuses and they appear to be good.
AND when testing your two radiator fans directly, one doesn't seem to work.
Based on what you've checked so far, the system should at least try to operate with only one fan unless something else is bad OR there's no freon.
A gauge set to check pressures would likely be the easiest next step...
I have a 2001 ALH 5-speed manual Jetta GLS sedan.
My AC system worked fine one night as usual, didn't work the very next day.
No fan operation with key on, AC button pressed, and blower switch on.
Turns out in my case the suction line had been damaged and released all the freon when I parked the car for the night... No freon = no fans = no AC.
Since you're having a problem where only one fan works and that's only when it's jumpered directly, replace the fans regardless of whatever else is wrong.
According to the info in this thread they're in parallel so when one's getting powered for low or high speed operation the other is too. Therefore if only one fan is running then at the least you have a bad wiring connection to one fan or a bad fan, although there's obviously something else wrong as well.
Plus, as stated in this thread, having only one fan working will still blow cold air but overwork the compressor...
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zukikat
Veteran Member
Side note, some aftermarket fans aren't wired properly or don't work on both speeds!
ALWAYS test a new set for proper pin wiring and operation before you install them.
A buddy's '03 ALH sedan broke a fan blade during engine work so he bought a whole new set from the local auto parts store and he started having overheating problems whenever he turned his AC off. Turns out they were only wired from the manufacturer to run on high speed! It took the parts store several tries to find a set that worked properly.
ALWAYS test a new set for proper pin wiring and operation before you install them.
A buddy's '03 ALH sedan broke a fan blade during engine work so he bought a whole new set from the local auto parts store and he started having overheating problems whenever he turned his AC off. Turns out they were only wired from the manufacturer to run on high speed! It took the parts store several tries to find a set that worked properly.
Golf2K
Well-known member
I may give it a try but I'm guessing the fan is toast, thanks for the input
I'm gonna replace the small fan for sure, Im just trying to get a good deal, my options are get both fans used for $100 and 100 day warrenty, which Id rather pay much less. I can find a used single fan $50 plus shipping or new small fan off the internet for $100 shipped.
As for the Fan Control Module I suspect its problematic, Im gonna go for a drive to see if my large fan comes on when the car reach's 92c Degrees.
Here is a video of what they look like on the inside (FCM)
its for a a3 but I am sure they are much the same.
https://www.youtube.com/watch?v=4i1PZRTU0q0
Golf2K
Well-known member
Well I got it up to 94.6c degrees the fan did not come on, the manual says they should come on at 92c.
Time to remove the FCM
Time to remove the FCM
Jet 02
Well-known member
100 Deg. and NO A/C
Well, I read the first page.. Fans had worked yesterday but not this afternoon.
Read the Mk4 fan test page.. Went out to the car, key on, ac button "in" interior fan on mid position. I check and I have no low speed fans (large fan was replaced when I first bought the car)
So the next step is to check fuse 8, one of the green 30 amp fuses above the battery. I wiggled the fuse and the fans spun up.
In less than three minutes of testing...
Whoopie !! no new compressor, no R134, no hot commute!
Dan, Thank you Thank You Thank You!!
Jet 02
2002 Jetta TDI
Well, I read the first page.. Fans had worked yesterday but not this afternoon.
Read the Mk4 fan test page.. Went out to the car, key on, ac button "in" interior fan on mid position. I check and I have no low speed fans (large fan was replaced when I first bought the car)
So the next step is to check fuse 8, one of the green 30 amp fuses above the battery. I wiggled the fuse and the fans spun up.
In less than three minutes of testing...
Whoopie !! no new compressor, no R134, no hot commute!
Dan, Thank you Thank You Thank You!!
Jet 02
2002 Jetta TDI
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
@Jet_02 get that fuse and panel fixed up soon, if it's not melted all to heck already. A new fuse and scrubing that connection is cheaper than a melted down panel.
Jason
Jason
zukikat
Veteran Member
Just a thought...
An entire complete new plug-n-play fusebox assembly (with fuses and positive battery cable already included) can be had from Amazon.com for around $25 - $40 usd rather than cleaning and re-cleaning and trying to repair an already corroded and melty one over and over again... Just double-check each of the included fuse values and match them up to your originals if they're not all correct.
An entire complete new plug-n-play fusebox assembly (with fuses and positive battery cable already included) can be had from Amazon.com for around $25 - $40 usd rather than cleaning and re-cleaning and trying to repair an already corroded and melty one over and over again... Just double-check each of the included fuse values and match them up to your originals if they're not all correct.
supton
Top Post Dawg
Might run into trouble. I had no problems this summer and last summer with only the smaller fan being operational; the larger fan is siezed on mine. AC usage and no ac usage, never gave indication of problems. But last I knew NH was a bit cooler than AZ... YMMV. To be sure, I do little city driving.
[Was going to replace but I stripped the lower torx bit, then plain forgot about it until end of summer, then figured, if it can go all summer then it really wasn't needed.]
zukikat
Veteran Member
My first ALH sedan had one dead fan which I didn't realize when I bought the car at 234k miles on it in the middle of our short erratic winter season down here in Southeast Louisiana several years ago.
The factory temperature gauge sat rock solid centered the whole time but when I added a scangauge it became obvious that the car was running "warm" even without AC use.
Whenever I used the AC system for defrosting in the winter sleet/rain the temperature would get over 200F and I'd smell coolant when I parked the car but it didn't leave any puddles. It was during a search for the source of the hot coolant smell that I noticed only one fan working.
The coolant reservoir level wasn't visibly dropping and the factory temperature gauge allegedly indicated that everything was fine so I didn't stress over it and hadn't made the connection between a dead fan and higher operating temperatures until after the car was totalled and I got to see the correct behavior on the scangauge from my replacement ALH sedan which has properly working fans.
I never got to see how my first ALH behaved with only one working fan in our HOT southern summers but the key here is that the dash gauge said everything was fine the whole time when obviously it was not.
Note that apparently some ALH's can go with no fans and still appear to behave normally while others get really hot, even with a brand new genuine VW thermostat.
If someone lives in a cooler climate this would be far less obvious.
Also note that I'm 99% certain that my 2001 fans are both the same size, as is a buddy's 2003 (or at least the ones it had when he bought it used were) while the 2004+ PD's appear to have 2 different size fans.
The factory temperature gauge sat rock solid centered the whole time but when I added a scangauge it became obvious that the car was running "warm" even without AC use.
Whenever I used the AC system for defrosting in the winter sleet/rain the temperature would get over 200F and I'd smell coolant when I parked the car but it didn't leave any puddles. It was during a search for the source of the hot coolant smell that I noticed only one fan working.
The coolant reservoir level wasn't visibly dropping and the factory temperature gauge allegedly indicated that everything was fine so I didn't stress over it and hadn't made the connection between a dead fan and higher operating temperatures until after the car was totalled and I got to see the correct behavior on the scangauge from my replacement ALH sedan which has properly working fans.
I never got to see how my first ALH behaved with only one working fan in our HOT southern summers but the key here is that the dash gauge said everything was fine the whole time when obviously it was not.
Note that apparently some ALH's can go with no fans and still appear to behave normally while others get really hot, even with a brand new genuine VW thermostat.
If someone lives in a cooler climate this would be far less obvious.
Also note that I'm 99% certain that my 2001 fans are both the same size, as is a buddy's 2003 (or at least the ones it had when he bought it used were) while the 2004+ PD's appear to have 2 different size fans.
2000 Jetta - AC compressor & fans not turning
Looking for help from anyone here familiar with a 2000 MK4 / A4 VW Jetta's manual (not Climatronic) AC system:
In the last week, my AC would intermittently stop working. Sometimes it would work, sometimes not, either from start or while idle. When it works, it is cold and it does not turn off as long as I have the engine on. When I shut down the engine and turn it on again, sometimes it will work, sometimes not.
I found the following while troubleshooting:
1. With ignition on, fan speed to lowest, AC button on, both cooling fans are not turning. With engine on, and fan speed on, and AC button on, the cooling fans and compressor are still not turning.
2. I checked both low & high pressure of my AC with my manifold gauge with engine off results in 100 psi static pressure. I could only check static pressure because the AC compressor wont turn on.
3. There is a voltage of 3.5v from the AC compressor wiring harness - normal voltage is 9 to 9.5 though.
Given these findings, I've narrowed down the faults to three parts:
a. the high pressure sensor which sends a signal to the Fan Control Module to stop both fans and AC compressor if there is too much refrigerant pressure or not enough pressure in the system is not sending a signal,
b. the Fan Control Module which receives signal from the pressure sensor to power or cut off power to both cooling fans and the compressor is receiving the signal but can't send power to those parts,
c. the temperature control dial in the central stack which would basically not turn the AC compressor on if it's stuck in heater mode - though no heat is coming out of the vents.
Any ideas? I just don't want to throw all three parts at this problem if I can eliminate them one by one first.
Looking for help from anyone here familiar with a 2000 MK4 / A4 VW Jetta's manual (not Climatronic) AC system:
In the last week, my AC would intermittently stop working. Sometimes it would work, sometimes not, either from start or while idle. When it works, it is cold and it does not turn off as long as I have the engine on. When I shut down the engine and turn it on again, sometimes it will work, sometimes not.
I found the following while troubleshooting:
1. With ignition on, fan speed to lowest, AC button on, both cooling fans are not turning. With engine on, and fan speed on, and AC button on, the cooling fans and compressor are still not turning.
2. I checked both low & high pressure of my AC with my manifold gauge with engine off results in 100 psi static pressure. I could only check static pressure because the AC compressor wont turn on.
3. There is a voltage of 3.5v from the AC compressor wiring harness - normal voltage is 9 to 9.5 though.
Given these findings, I've narrowed down the faults to three parts:
a. the high pressure sensor which sends a signal to the Fan Control Module to stop both fans and AC compressor if there is too much refrigerant pressure or not enough pressure in the system is not sending a signal,
b. the Fan Control Module which receives signal from the pressure sensor to power or cut off power to both cooling fans and the compressor is receiving the signal but can't send power to those parts,
c. the temperature control dial in the central stack which would basically not turn the AC compressor on if it's stuck in heater mode - though no heat is coming out of the vents.
Any ideas? I just don't want to throw all three parts at this problem if I can eliminate them one by one first.
BobnOH
not-a-mechanic
Yes, you've found the right thread. All your answers are here. For the stuff other than the "fans not working" there are links in the very first post.
Then we have 80+ pages of Dan answering the same issues over an over.
Sounds like you've already made an excellent start!
Then we have 80+ pages of Dan answering the same issues over an over.
Sounds like you've already made an excellent start!
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
@gregoron - it sounds like pressure sensor from the description of how your car is acting, but I would hit up the links and double check the system first.
Jason
Jason
Thanks, I wanted to check the HPS but I don't have the instrument yo do it. What bothers me is that voltage to compressor is low at 3.5v. But, when it works the AC blows cold and doesn't stop. It also tends to work when engine is warmed up. I think it's a temperature and pressure thing, thus leading me to suspect the HPS.
BobnOH
not-a-mechanic
Posts 1, 1171, 1198 seem applicable
^ Thanks. Those posts apply. I had the driver side fan disabled for a while but I don't think my compressor's bleed off valve went off. It's still sealed since I replaced it a year ago. I also replaced the faulty fan. I think my high pressure sensor is faulty. I'll bite the bullet and replace it then post my results here.
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
Be careful doing voltage checks on VW. They like to send a voltage down a circuit to monitor its condition. But that there is no current (IE: use a test light to put load on that circuit and your volt meter should drop to 0V).
Jason
Jason
Ok, bought the high pressure sensor from NAPA for $70, installed it, and turned on the AC and it works! Both fans are working and the compressor kicked in. It wasn't working before I replaced the HPS. I'll have to see if it'll continue to work consistently though.
HPS was made in Germany by Altrom. It looks different from OEM but it fit right.
HPS was made in Germany by Altrom. It looks different from OEM but it fit right.
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Aridzonan
Member
Problem Follows ThermoSwx..
Dan, I've got a weird one. I'm following the "A4 fan troubleshooting" procedure. The problem follows the Thermoswx. Where I jumper out pins 1&2 (Fans run slow), jumper out 2 & 3, turn vehicle on, (Fans run fast). I've changed out the Thermoswx to no avail. I thought there may be a bad connection. So, I used some spade lugs, made jumpers to make sure there was contact between the ThermoSwx and the connector and still the fans do not spin.. Any guesses?
Thanks,
JQ
Dan, I've got a weird one. I'm following the "A4 fan troubleshooting" procedure. The problem follows the Thermoswx. Where I jumper out pins 1&2 (Fans run slow), jumper out 2 & 3, turn vehicle on, (Fans run fast). I've changed out the Thermoswx to no avail. I thought there may be a bad connection. So, I used some spade lugs, made jumpers to make sure there was contact between the ThermoSwx and the connector and still the fans do not spin.. Any guesses?
Thanks,
JQ
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
Defective new thermo switch? Coolant in radiator tank is not getting hot enough? Are the fans never running or just not running with the A/C?
Jason
Jason
Does it worth to build a PWM circuit that controls fan speed based on condenser temperature?
It's a piece of cake to build it with a PIC12F683, a LM35 temperature sensor, a P-Channel MOSFET and some other minor components.
My goal is to optimize fuel economy and increase the life expectancy of my fans that are still working fine.
What should be the optimal temperature on condenser? I know that the ideal is closest to ambient temperature.. but this would need too much airflow and draw power for the fans.
It's a piece of cake to build it with a PIC12F683, a LM35 temperature sensor, a P-Channel MOSFET and some other minor components.
My goal is to optimize fuel economy and increase the life expectancy of my fans that are still working fine.
What should be the optimal temperature on condenser? I know that the ideal is closest to ambient temperature.. but this would need too much airflow and draw power for the fans.
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
The system is basing the fan speed and usage on the pressure in the high side of the Freon circuit. Three wire G65 is outputing a PWM signal based on pressure, four wire is a high and low pressure switch setup based on preset pressure limits.
Don't forget to include engine temperature in the control circuit design for the fans. Also what about drivers to activate the fans? How about the 40+Amperes of current they draw?
I think you would be basically engineering a FCM. Sounds like a fun hobby project.
Jason
PS: I believe the fan control system in the B5.5 Passat is a much simpler relay setup. Worth a look?
Don't forget to include engine temperature in the control circuit design for the fans. Also what about drivers to activate the fans? How about the 40+Amperes of current they draw?
I think you would be basically engineering a FCM. Sounds like a fun hobby project.
Jason
PS: I believe the fan control system in the B5.5 Passat is a much simpler relay setup. Worth a look?