Check your radiator/condenser fan operation NOW

[olemiss36]

so, looks like I'm going through this now as my AC isn't working.. I haven't used a jumper yet because I need to go buy one, but my issue is on a mk4 manual. The right fan works, the larger one on the left doesn't spin at all, low or high. I checked the fuses and those are all good. The fan itself is not free spinning, should it free spin like the smaller passenger side? If that is my issue hopefully it's just a simple fan swap.

 

[Genesis]

90%+ odds the fan is simply bad. Disconnect the wire at the FCM and ohm it out; you'll probably find it open. The small ones rarely fail but the large ones puke all the time.

 

[nitrousneil]

So I’m having a no power to my ac pump issue, I’ve tested all fuses and wires with power to everything but the ac pump, with that said there is power to my drivers side fan but it’s not working but spins freely, will this cause no power to go to the ac pump? Passenger side fan is running.

 

[Genesis]

If one fan is running then that's not the reason it won't pull in. Check the wiring to the clutch and the clutch coil itself. If the coil is open then you found the problem, likewise if it's good but you see no voltage going to it; if the fans are running with the key on, fan in any position other than OFF and the button IN then the clutch SHOULD pull in when the engine is running. Odds are it's a wiring problem or the clutch coil itself is bad.

 

[DudaEnergy]

So if I bypass power on the thermoswitch, I get nothing for the slow speed and for highspeed, only one fan runs. Checking for power on the thermoswitch, I have it at 12v. But if I "hotwire" it, only that one fan runs at high speed. If I run power directly to the fans, I get NOTHING on all pins. (Weird?) Checking resistance, one fan (the one that runs highspeed) gives 0.6 Ohmz on one set of pins and 1 Ohm on the other set. The non-working fan gives 0.6 Ohmz on one set, nothing on another.


The instructions say it's a wiring fault if I can't get the fans to run with the "hotwire." What exactly am I checking for? I will follow the cables from the power switch to where it meets the fans and eventually find a disconnect? What baffles me is no fan runs with direct power connected to them. But I can get high speed fan on one fan. (no low speed works at all). This isn't making sense to me. it seems like one fan MAY be dead since it only reads resistance on one lead (or one lead/slow speed is totally broken?)

 

[wonneber]

So if I bypass power on the thermoswitch, I get nothing for the slow speed and for highspeed, only one fan runs.

How are you sending power to each fan?
If you unplug the fan and supply power to it the fan has no ground.

Both fans get high speed power from the same pin of the fan control module.

Both fans get low speed power from the same pin of the thermal switch.

Each fan has it's own ground wire going to the body ground on the left side of the engine compartment.

 

[Airdirect]

Help! Mark IV Golf A/C Clutch and Fans won't engage

I am working on my sons 2001 Golf GTI 1.8T. I have read and printed out Dan's trouble shooting guide. I am stumped and need more help.

Symptom:

With ignition on and a/c selected with fan control in low, i do not have any radiator fan or compressor clutch.

Items Checked:

Fuses 5, 16, 25, & green fuses on top of battery.

Compressor clutch, applied 12 volts to green/black wire on 10 pin connector at FCM. Applied ground to brown/black wire on FCM. A/C Clutch engages.

Monitored blue/red wire on 10 pin connector (FCM) for 12 volts when A/C Switch is on. Power follows switch position.

Checked Ambient temperature switch at FCM 10 pin connector, bl/ro to gn/bl 700 ohms. Logged into the ECM and it is showing approximately correct temp (86 degrees).

Checked high pressure switch connector (by expansion valve) for 12 volts, checked white wire and have 2.3 volts present with system turned on.

Applied a short across the radiator thermal switch, I get both low and high fan speeds depending on on contacts shorted.

Operated engine at 3,000 to see if compressor clutch engaged, it did not.

System has static pressure of 110 on both low and high sides.

At this point I believe I might have a bad FCM module, your help would be very much appreciated.

David L. Jones

 

[Airdirect]

A/C problems help, it's hot in Texas!

Anybody help with A/C problems?

I am working on my sons 2001 Golf GTI 1.8T. I have read and printed out Dan's trouble shooting guide. I am stumped and need more help.
Symptom:
With ignition on and a/c selected with fan control in low, i do not have any radiator fan or compressor clutch.
Items Checked:
Fuses 5, 16, 25, & green fuses on top of battery.
Compressor clutch, applied 12 volts to green/black wire on 10 pin connector at FCM. Applied ground to brown/black wire on FCM. A/C Clutch engages.
Monitored blue/red wire on 10 pin connector (FCM) for 12 volts when A/C Switch is on. Power follows switch position.
Checked Ambient temperature switch at FCM 10 pin connector, bl/ro to gn/bl 700 ohms. Logged into the ECM and it is showing approximately correct temp (86 degrees).
Checked high pressure switch connector (by expansion valve) for 12 volts, checked white wire and have 2.3 volts present with system turned on.
Applied a short across the radiator thermal switch, I get both low and high fan speeds depending on on contacts shorted.
Operated engine at 3,000 to see if compressor clutch engaged, it did not.
System has static pressure of 110 on both low and high sides.
At this point I believe I might have a bad FCM module, your help would be very much appreciated.
David L. Jones

 

[SilverGhost]

I am working on my sons 2001 Golf GTI 1.8T. I have read and printed out Dan's trouble shooting guide. I am stumped and need more help.

Symptom:

With ignition on and a/c selected with fan control in low, i do not have any radiator fan or compressor clutch.

Items Checked:

Fuses 5, 16, 25, & green fuses on top of battery.

Compressor clutch, applied 12 volts to green/black wire on 10 pin connector at FCM. Applied ground to brown/black wire on FCM. A/C Clutch engages.

Monitored blue/red wire on 10 pin connector (FCM) for 12 volts when A/C Switch is on. Power follows switch position.

Checked Ambient temperature switch at FCM 10 pin connector, bl/ro to gn/bl 700 ohms. Logged into the ECM and it is showing approximately correct temp (86 degrees).

On this car ('01 GTI) the temperature in ECM is NOT the ambient temperature switch. Also, notice it is call a "switch", not a sensor.

Checked high pressure switch connector (by expansion valve) for 12 volts, checked white wire and have 2.3 volts present with system turned on.

4 wire switch or 3 wire sensor?

Applied a short across the radiator thermal switch, I get both low and high fan speeds depending on on contacts shorted.

Operated engine at 3,000 to see if compressor clutch engaged, it did not.

Don't remember the exact cut off RPM, but repair manual usually asks for 1200-2000 RPM during tests. That may have been too high and actually shut AC off.

System has static pressure of 110 on both low and high sides.

At this point I believe I might have a bad FCM module, your help would be very much appreciated.

David L. Jones

Just a couple things that caught my attention.

Also I have been burned by checking pressures and seeing standing pressure look good, assumed full Freon charge. But after some testing and coming back to Freon charge found only 80-100g instead of 650g.

Jason

 

[Airdirect]

MK4 Golf GTI Air Conditioning Problem

Jason,
Thanks for your reply. We have the three wire sending unit. I picked up another ambient temperature switch at the junk yard yesterday. I believe this switch is located by the A pillar under the cowl plastic tray, rear drivers side of the hood. I also picked up two radiator fan control modules, and two pressure sending units. Hopefully something in this collection will allow it to start working again. I do not have a way to measure the actual refrigerant in the system, normally I charge until I have around 30 to 35 on the low side with high side 170 to 200. Jason, I really appreciate your input and help!
David L. Jones

 

[SilverGhost]

The 3 wire is a sensor that out puts a square wave that looks like PWM signal (I believe) to the FCM indicating actual pressure in system. The 4 wire is high and low pressure switches. I'm not sure what pressure 2.3V indicates.

Recover the system and charge a preset amount of Freon. Too much or too little will cause issues. Some of them right away, but others are long term issues. FYI - I regularly see 25-28psi low on good, new system, 30-38 on working, but old or overcharged system.

I have seen the test for ambient temp switch is a paper clip in the connector.

This really sounds like a system that FCM or ECM saw a problem and shut it off. Just got to find the problem. I have even heard of a couple people finding wires corroded out in the harness before FCM, but I wouldn't expect that in Texas like I would in Toronto.

Jason

 

[Airdirect]

MK4 Golf GTI Air Conditioning Problem

Got the Air Conditioning fixed. After trying five high pressure sending units, the sixth one fixed the problem. We now have ice cold A/C just in time, the forecast for tomorrow in Texas is 100 degrees.

 

[BobnOH]

...................................After trying five high pressure sending units, the sixth one fixed the problem.............................

That sounds nuts, where did you get those?

 

[wonneber]

He mentioned the junk yard in post1901.
I can't remember the last time I visited one.
Has to be while I was still in NJ 33 years ago.

 

[Spenlowren]

Can I use OBD scanners for diagnostics? I've been using mainly MotorData OBD on Android https://play.google.com/store/apps/details?id=com.motordata.obd It got many functions.

 

[olemiss36]

I started with the large fan not running, replaced that and it's fixed but still no clutch engaging. so i've run through these tests from the guide, and i'm getting 9.3V to the compressor and 9.5V under load and the clutch isn't engaging still. The G65 sensor is giving me about 2.3V so i don't think thats it either. I haven't checked all the leads at the FCM but considering I'm getting the correct voltage at the compressor it shouldn't have anything to do with the FCM would it?

 

[Genesis]

What's the resistance across the clutch coil? If it's open you just found the problem.

 

[SilverGhost]

Quick tip - you need to check voltage to compressor clutch UNDER LOAD. Something a simple as a test light (regular bulb, no LED) is enough load.

Jason

 

[olemiss36]

What's the resistance across the clutch coil? If it's open you just found the problem.

0L so guess that means it's the clutch?

 

[Genesis]

0L so guess that means it's the clutch?

Uh, yep. It should read something like 4ish ohms.

 

[Nuje]

When doing the initial fan test (ignition on, AC button pressed), what's the cause of one fan (small) turning, but the other not?

Also, no cold air blowing (even with engine running). But, figuring out the bad fan first.

 

[Genesis]

When doing the initial fan test (ignition on, AC button pressed), what's the cause of one fan (small) turning, but the other not?

Also, no cold air blowing (even with engine running). But, figuring out the bad fan first.

It's quite likely the fan itself is dead. The one that usually dies is, as you're seeing, the driver-side one. It's also quite-frequent for it to die only on low speed (that is, the resistor that drops the speed burns out, but the motor itself is still functional, so it will run on high -- at least for a while.)

 

[olemiss36]

so the coil was reading 0.L as posted earlier and I ordered a new one on amazon It's reading 4 ohms of resistance so the question is should I just replace the coil or the compressor all together? I'm not that comfortable with doing the job myself with the belt removal and all i have to get the car up is a jack to work underneath the car so i found a guy that will do it for $200. Most of the shops I called said the coil is the first indication of a failed compressor and would only replace the entire compressor. This guy will do the entire compressor swapout for $260. I guess the question is, is it worth the $200 gamble to replace the coil only or should i spend the $150 on a compressor and replace the whole thing? My compressor is the original one and the car has 220k on it.

edit: going to attempt the repair wed with a buddy, if that doesn't work i'll go with the full compressor replacement.

 

[ymz]

... is it worth the $200 gamble to replace the coil only or should i spend the $150 on a compressor and replace the whole thing?

Only possible snag is that when trying to remove the nut holding the clutch in place, the compressor shaft may break (given the age of the car)... in that case, you'll be replacing the entire compressor, which will entail the "expert" level in removing and replacing the refrigerant and oil...



Good luck,



Yuri

 

[olemiss36]

replacing the coil seemed to fix it.

 

[towforce]

Just ran this test a few weeks back and found the main fan dead. I had recently noticed that doing some high passes in high heat my normally rock solid temp gauge would creep up a bit.

Pulled out the main fan, pulled the motor apart and found the brushes stuck and brush holders deformed and a mess. Cleaned it up and got it working but its just a patch job so I think a new fan is going to tag onto my next IDP order.

Curious, has anybody give any feedback on the Large/Small fan complete kit? https://www.idparts.com/dual-cooling-fan-assembly-a4-p-10375.html

Given the desert climates and mountain pass stuff that I do, can't imagine the second fan is in too good a shape, might make sense to just change them both?

Martin

 

[Coasty]

I bought a big and small cheapo ebay fan about 4 years ago and they are still working great, even though they never shutoff in South Florida.

Sent from my SM-G930P using Tapatalk

 

[ToxicDoc]

Just ran this test a few weeks back and found the main fan dead. I had recently noticed that doing some high passes in high heat my normally rock solid temp gauge would creep up a bit.
Pulled out the main fan, pulled the motor apart and found the brushes stuck and brush holders deformed and a mess. Cleaned it up and got it working but its just a patch job so I think a new fan is going to tag onto my next IDP order.
Curious, has anybody give any feedback on the Large/Small fan complete kit? https://www.idparts.com/dual-cooling-fan-assembly-a4-p-10375.html
Given the desert climates and mountain pass stuff that I do, can't imagine the second fan is in too good a shape, might make sense to just change them both?
Martin

Personally I would change both and keep the small fan as a spare. IDparts typically sells good products (even if cheap/Chinese) and for that price I don't think it's risky, no?

 

[Genesis]

The small fan, for some reason, rarely fails. I have no idea why. My '03 has the OE small fan in it.... not so for the big one! And I live in Florida...

 

[RayBrubaker]

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.