Help! Radiator fans not working and AC

Hi all, I haven't found anything in search that fits MY problem. It's warm here now, and a couple days ago I needed to run my AC during rain to defog the windows on my 01 Beetle TDI, it didn't work correctly. I'm looking down in the engine bay and I can see the compressor kick on, I can hear it and feel it when I flick the switch. I thought it might have a slow leak since the condenser had to be replaced a few years after a screw went through it on the interstate so I hooked my gauges up to it and it's got freon. Reading a little high actually, turn the AC on and the gauges move down some. The radiator fans are NOT coming on. I'm afraid it might overheat if I get stuck in traffic since this is my daily commuter. Where do I check the fans circuit? It has been super cold all these years. Otherwise it's been a great car since I bought it new.

I checked the fan circuits as per the Bentley manual today, When I jumper the terminals at the thermo switch on the radiator the fans come on, but only high speed. They won't work on low speed. I turned the AC on with the fans on hoping it would be cool but it still won't cool. My gauges prove the compressor is kicking in, but the numbers don't make sense...the low side is reading high and the high side is reading low....compressor going out? I've done a compressor job on two different vehicles, one being a Mercedes and it was a booger to do. Is it so difficult to do on the Beetle? I know the compressor is on the bottom, but it's hard to get to the hoses and stuff under the hood on the Beetle. May be time to let my TDI go and just drive my new Cadillac...but I hate to 'cause I love this little bug.

Your compressor is just fine as well as the freon, evaparator, condenser, etc.

The problem is most likely that the low speed on the two fans is burned out...........

If you turn on the key, turn on the fan on the dash, and press the AC button, both fans out front should come on. If not, the low speed aspect is burned out.....Or, the brushes are shot. You can unplug each fan and test to see if brushes or the low speed is the culprit. Each plug has three connections. One is ground and the other two are high and low. If the fans work on high the brushes are okay. So, that would mean that the electrical resistor internal that "consumes" current to provide slow speed is burned out!

Side note: If the dash fan doesn't work the above test will not work either.

Most folks here swear by OE replacement on the fans. I admit, I went the China route from eBay. However, I have had issues with two new Fan Control Modules. The FCM is located below the battery. My AC compressor clutch will kick-in with the Old OE FCM but the new fans will not come on. So, I installed the "new" FCM only to learn that the fans worked fine but the AC Clutch would not kick-in. So, right now, I've got my on relay system working! ............don't trust those $39.95 FCM regardless of where they come from. I have had two of them to be bad straight out of the box!

From some other research I've read it could be my refrigerant control valve inside the compressor....my gauges don't fluctuate much when the compressor comes on, it won't produce suction on the low side...they say it can be replaced with the compressor still in the car, just have to have it discharged, open the back and replace, reclose it, pull vacuum and recharge. I don't know....I may have two different problems that just surfaced at the same time. Murphy's law.

When I did my testing, as I jumped for the high speed test, the relay clicked and the fans came on. For low speed, no click, no fans. Bentley manual seems to think it's the FCM.
Oh, and I was just checking the power to the fans at first....for the hi speed test I had power at the middle terminal on the actual fan plug ins, but on low speed no power at the fan plug in...forgot to type that above....so the power was going through the fan control to the connector. I can live without AC for a little bit but I have to make sure the fans will work in the heat thats coming in the next few weeks.

To be absolutely sure as to whether or not the low speed is out on the fans, you need to unplug them for testing. Test directly at the plug/connector for high and low speed as previously described. I use a length of wire from the hot post on the battery and another length of wire for the ground with female connector.

Ah, the warm weather.... here come the bad fans, bad fan controllers, broken water pump impellers....

If you only see slight freon pressure changes it is probably a bad compressor. From what I have read they are varible pitch and ts hung-up. I have had this happen on 2 different VW's after extended periods of non-A/C use. A new compressor and were all cool again.

That's what I see. Then the fans, I tested them at the plugins for them separately and only have power for high speed....sounds like FCM to me and the Bentley manual. Thanks for all the input, just needed some second opinions. I think I have two different problems that have surfaced at the same time, go figure. I can do both of these replacements if needed myself.

Ok so my a/c worked for about 5 min the other day. So now i trying to figure out what went wrong.
Seems a few things. First off fans would not come on when ac turned on. I got those working lagre fan seized and small one wires conection. So they both work now.
Cross pin 1 and 2 on HP switch fans go to hi but no clutch.

Checked volts at clucth only have 4 volts, but thats 4 volts at all times, key on or off ac on or off, always 4 volts.

So got a used fcm from local wreckers and now ac clutch getting 4.5 v at all times still.

M i right to assume that both fcm, are bad?


And for ****s a giggles i thought i would check clutch omhs and it a open circuit, no omh reading at all. And when i put direct power and ground from battery nothing happens at all.
So that would say clutch gone to right?

Ambient temp sensor shows .3 ohms on 200 scale.
Is this good ?

Any idea why both fcm and clutch would go out together. Could be a power surge due fans being messed up?

Thanks for help.

They work fine on both fcm

leadfoot,
You are not the OP, and do not have the same problem as the OP. So a post in this thread, even directly after your post, should not be seen solely as an answer to you.

Post # 10 however has valuable info for both you and the OP.
That link has documents in post #1 that can help troubleshoot MKIV AC systems in some detail. For instance it gives the normal resistance value for a good clutch coil.
The clutch coil is easily replaced.

Leadfoot,
Your compressor clutch (or wiring) is bad.
What is the manufacturing date of your car?
How many pins were on your "HP switch", 3 or 4?
If it is four pins then it is a double switch.
If it is 3 pins, then it is not a switch at all but a High pressure pulse width modulated SENSOR. These were put in after May '99 build dates. SENSORS cannot be jumpered; you just tear things up from putting 12 volts where signals should be.

Dan

Sorry dan for posting confusion still new to these forms.
Manu date is 03/2000 the hp switch is 3 post. Post 1 has battery power to it.

So it is not a switch. It senses the pressure and sends out a Pulse width modulated signal proportional to the pressure.
You cannot jumper around it - you will damage something - just blow a fuse if you are lucky.

DanG144 said:

So it is not a switch. It senses the pressure and sends out a Pulse width modulated signal proportional to the pressure.
You cannot jumper around it - you will damage something - just blow a fuse if you are lucky.

Click to expand...

ok thanks Dan. I'll have to work on getting compressor fixed.
What do you think about the fcm not even puting out 12v to compressor? and always at 4.5 volts even with key off.

Many switches are now electronic, not contacts, and when you measure with a modern high impedance volt meter, it shows some voltage, but no real power can be transmitted through it. So the 4.5 v is not a problem.

It should go to 9.5 or so when it switches on.

What are your refrigerant pressures running?

There is little evidence that you had even one bad FCM.

You can get a clutch coil and replace it very cheaply and easily, but there is no guaranteee that is all that is wrong with the compressor (but that is often the case.)

There are several things that can cause your fans not to work. Most are covered in the thread referenced above.

DanG144 said:

Many switches are now electronic, not contacts, and when you measure with a modern high impedance volt meter, it shows some voltage, but no real power can be transmitted through it. So the 4.5 v is not a problem.

It should go to 9.5 or so when it switches on.

What are your refrigerant pressures running?

There is little evidence that you had even one bad FCM.

You can get a clutch coil and replace it very cheaply and easily, but there is no guaranteee that is all that is wrong with the compressor (but that is often the case.)

There are several things that can cause your fans not to work. Most are covered in the thread referenced above.

Click to expand...

well pressure while not running was 90 with a cool engine.
I did notice a couple time the meter would jump up to about 9v but would not stay long enough to get a full reading just happen to see meter numbers changing out of corner of eye.

clutch turns by hand no problem, doesn't sound bad either.

as for the coil are they universal or fit to only make and model?

I got my fans working good now, replaced both of them but only 1 was bad,(seized) other was the wire connector, the ground was rotted out. so I keep that one as a spare.
thanks

The coil must be for your compressor model. I have replaced the coil off of one sanden clutch style with one from another sanden clutch style with success. You do have to change out the connector, typically splicing the connector from your old coil to the new coil.

Inspect your connector closely as your connector is sometimes the culprit; your coil may be good.

There are 3 clutches for the Sanden 7V16 CH201, 202, 203. If you have to replace the entire clutch assembly, then you must replace like with like, as the splines on the shaft are different. http://worldaire.com/pdf/2005WorldaireClutchCatalogSept1.pdf page 26 of the pdf, numbered page 25 shows the clutch styles.

In the US http://www.polarbearinc.com/ is a good place to buy parts, but there are other places. Not sure about Canada.

I do have some clutch coils for the Sanden compressors, since they were donated to me, I just charge shipping costs to send them to club members. This usually takes several weeks for Canadian and 2 days for US shipping. Frankly you can probably get one locally from a junk yard or other member's old compressor for cheaper than shipping and without the delay.

It seems shipping was about $25 last time I shipped one to Canada.

thanks for info Dan.
I looked at my compressor it is a sd7v16 but not sure of that ch number, with your pdf link there I think it is a 201 but will have to double check tomorrow to be sure. There where other numbers like a 1215.
I seen some coils on ebay and they where using that number 1215 among others saying they will fit all those models. so I assuming that numbers means something as well.

If I doing just the coil then i don`t need to confirm the clutch anyways right?

Right.

thanks will post back here when I get coil and Install it.<br>

Update....yesterday I installed a brand new compressor AND a genuine VW fan control module....everything FIXED! Thanks for your help

How hard was it to install and refill the system?

leadfoot69 said:

thanks will post back here when I get coil and Install it.<br>

Click to expand...

Ok finnally installed new coil and a/c working 100% again.
Wasn't hard to change coil at all, got it all off without removing compressor from engine but could not get it back on that way, lol. had to remove compressor from engine and let it hang down to reinstall C-clips, but all in all less then 30 mins in my drive way.
Thanks for the help.

Question to ask for AC gurus, so if the compressor and AC system is bad mk4 tdi no free on then the fans do not work at all even when g12/water temp reach the temp limit,, does the radiator switch still turn radiator fans?

Yes, the fans will still kick on with high temp, but on the diesels you are not likely to ever see this, because they only make heat when under load.

As soon as you return to idle, and open the hood to check, the coolant temp would have already dropped and leveled off and the fans would no longer be needed.

I just drug a car home yesterday with my Golf (a Jetta on a dolly), it was 98F and VERY humid. I was running 65+ down the highway for 50+ minutes, as soon as I pulled in the driveway and shut the car off, the fans shut off. They were only running because of the A/C demand.

So, even with 200%+ weight load, on a near triple digit day, on the highway, even my slightly modded ALH was not producing enough waste heat to require the fans to run, LOL.

Two years ago I did a 30 minute session on New Hampshire Speedway in my wagon with PP764s and running 26 PSI boost. 5500 RPM shifts. Came into the pits and fans weren't running. I'm paranoid so I plugged in VCDS and coolant temp was 89c, not enough to make them run. Impressive.

what kind of temp are we looking at,,, before temp sensor on radiator sends the current to fans,, over 200F?

Copied from an old post:

Read the temperature in the Engine module, measuring block 7 is good, and read the temperature in Instruments, I do not have the measuring block.
This lets you read both temperature elements in the coolant.

The ECU will start the fans when it sees the temperature is too high, but I do not know the exact setpoint.

The radiator thermo-switch will start the fans when the temperature of the coolant about half way up the radiator is:

Bentley fan operating points:
low speed
on - 197-206 F (92-97 C)
off - 183-195 F (84-91 C)

Fast speed
on - 210-221 F (99-105 C)
off - 195 - 208 (91-98 C)

bought a good used AC compressor for my mk4 jetta whats the best way to know if I have correct amount of oil in compressor, hate to install it then to hydrolock it