Check your radiator/condenser fan operation NOW

weird electrical issue

So... I too am having issues with my fans. I can jump the thermo switch and run the low speed no high speed. I can power both speeds at the fan connectors then I realized that I must have key on to power the high speed through the thermo. i believe my issue has to do with the compressor not getting a signal to turn on. coil seems good im getting 3.5 ohms across it. i can jum it and then the fans and compressor will turn on. i then get cold air in the cabin and fans run on slow speed. if i take the jumper wire off they both continue to run on their own and im getting 12v to compressor, but as soo as i turn off ac or shut the engine off they will not come back on again unless i jump it. i have replaced fcm with vw part as well as the pressure sensor. thermo switch appears good. I have tested my ambient temp switchand it appears to be fine it has zero resistance. mine appears to be sending voltage through it at 2.6v. that is all im getting to the compressor at all times. Im wondering if there is a bad ground somewhere as i have had the refrigerant pressures checked and they are good when i jump the compressor. Any ideas? my wife is driving me nuts as it is 85 degrees here and her car is black! any help is appreciated thanks

Sadly mine is going into a shop due to this monday morning. New FCU, Fans, Tested switches. New fuse panel. No low speed :\


Im apparently ass backwards from most as the clutch has no issue engaging.

Good luck with the shop.

Do the fans run in fast speed all the time? or do they cycle off and then on in fast speed repetitiously? Or just no fans?

Well we figured out today the brand new fans (about 5-6weeks old) were both shot. Those were dorman fans.

Switch to another brand with lifetime local warranty since the dorman ones can't be warrantied direct, small fan works good so far. Big fan came on and caught fire on low speed. Go figure.

Car off we were getting 11.8v at the fans but thats also with the DRL's on, so I would assume thats normal? Getting the replacement tomorrow for the big fan. Do we think maybe its a weak battery? Its not quite 3 years old yet.

11.8 volts is a bit low, but it depends on what your battery voltage was. They should run fine on 11.8v.

I would pull the green fuse closest to the metal fuses and put it back in. This will clean the corrosion off of the fuse legs. Check that the fuses do not get hot when the fans are running. Problems with the fuse box causing high voltage drops and heating are common.

"Dorman fans" There's your problem. Get the after market fans out of there and just buy OE. IDParts.com usually has a good price on them.

I hate helping chase down problems and assuming because a part is "new" that it is not the problem.

/soap box

Jason

update
The new HP switch I bought from Amazon / Mueller Motorwerks / North Side Imports was bad . Was new , and looked to be a VW part .
I ask for and recived a replacement from the seller , They sent me another one .
When I opened the box it smelled like PAG oil , and the switch was in a zip bag , marker written part number .
It was covered with a dirt coating like it has already lived under the hood , and there was oil , and dirt/grit in the threads , with marks from the o-ring and top of the shraider valve .
I took pictures , cleaned it , and tried it , and my A/C now works.

I sent them an e-mail thanking them for making sure it worked before sending it to me , They responded " sorry the first one didn't work "

The short of it , A/C and both fans working again , thanks to the help and info on this forum .
Thanks All

SilverGhost said:

"Dorman fans" There's your problem. Get the after market fans out of there and just buy OE. IDParts.com usually has a good price on them.

I hate helping chase down problems and assuming because a part is "new" that it is not the problem.

/soap box

Jason

Click to expand...

Second set of fans I got are the same ones that IDParts sells. One of them burnt up before Even getting it off the jack stands. Second set are the exact same fans as the dorman ones that got pulled. So far so good with what i got now tho. The big one is the dorman style one. The smaller one is from the first set and its a TYB fan.

I didnt buy mine from IDParts but its the same PN and all from oriliey. Only advantage with that is they stock them locally and I can swap instantly without shipping.


http://www.idparts.com/dual-cooling-fan-assembly-new-beetle-p-3682.html

vs

http://www.oreillyauto.com/site/c/d...=Search_01389_1357613_4678&pt=01389&ppt=C0331

The box from oreilly says VDO on it as does the PN. They just rename it with another sticker for "store brand"

You might want to verify that your supply voltage is good. Low voltage at the fans causes high run currents and overheating.

11.8v off 13.7 running. I figure the 11.8 is about normal since the drl are on.

That is quite a voltage drop through the fuses and wiring...But I do not know what is normal.

Voltage at the fuse box is normal. Maybe a 0.1v drop. It's after that with all the sensors and such.

Just an update for those who see it. Autozone/Advance fan set for 99 beetle are garbage. So far so good on the second set from orilley. Same fans that IDParts sells (higher price at rilleys)

I have a 2006 Golf tdi and my a/c just started blowing hot yesterday. No previous problems with it. The blower works and both fans work. Checked all the fuses and didn't find a problem. The compressor clutch is not engaging. Any ideas?

tdismithville said:

I have a 2006 Golf tdi and my a/c just started blowing hot yesterday. No previous problems with it. The blower works and both fans work. Checked all the fuses and didn't find a problem. The compressor clutch is not engaging. Any ideas?

Click to expand...

Check for voltage at the ac clutch connector when the ac is supposed to be on.

AnotherPerson said:

Check for voltage at the ac clutch connector when the ac is supposed to be on.

Click to expand...

I did that today. Multimeter showed 10.65 volts

Always thought the ac clutch should be same voltage as what you read on top of the battery. Ohm the clutch connector on the compressor also. Being you do have power at the clutch i would lean towards a bad clutch.

I just read all 98 pages of this thread and the pdf posted by Dan and if my question was answered in there, I didn't see it. Apologies if it is but here it goes...will a problematic reading on the high pressure sensor cause the slow fan speed test with the key on, car off, ac on to fail? I know it will not engage the clutch but am unclear what it'll do to the fans. Most people on here went the direct route of jumping the rad thermoswitch to verify fan operation at both speed whereas I took the indirect route of opening my fan controller and manually activating each relay (both speeds work). The only troubling reading I'm getting is a higher resistance to ground (around 20 ohms) from the t14 connector and, if I'm doing it correctly, an oddly high reading from the pressure switch duty cycle.

AnotherPerson said:

Always thought the ac clutch should be same voltage as what you read on top of the battery. Ohm the clutch connector on the compressor also. Being you do have power at the clutch i would lean towards a bad clutch.

Click to expand...

Any idea what ohms I should be looking for at the clutch connector?

Around 4 ohms

Brkbeatsci said:

I just read all 98 pages of this thread and the pdf posted by Dan and if my question was answered in there, I didn't see it. Apologies if it is but here it goes...will a problematic reading on the high pressure sensor cause the slow fan speed test with the key on, car off, ac on to fail? I know it will not engage the clutch but am unclear what it'll do to the fans. Most people on here went the direct route of jumping the rad thermoswitch to verify fan operation at both speed whereas I took the indirect route of opening my fan controller and manually activating each relay (both speeds work). The only troubling reading I'm getting is a higher resistance to ground (around 20 ohms) from the t14 connector and, if I'm doing it correctly, an oddly high reading from the pressure switch duty cycle.

Click to expand...

http://pics3.tdiclub.com/data/517/A4_Air_Conditioning_Troubleshooting_Rev_7.pdf on page 8 gives the approximate set points and mentions that the fans and clutch are both off on low pressure...I know this stuff is hard to get through. A technical writer, I am not.

The ambient temperature switch also kills the fans and compressor on low temperature...

Take your resistance reading with the battery cable off. If you have current flow through the ground path, then it will give high resistance readings...

AnotherPerson said:

Check for voltage at the ac clutch connector when the ac is supposed to be on.

Click to expand...

As I think is covered in the PDFs in the first link, you have to have a load of about 4 ohms on the circuit to measure the voltage.

Some (most) of the fan controllers will read voltage due to leakage currents through the electronic switches, if the only load is a modern high impedance voltmeter. It is not like a light switch.

So to read the voltage, make sure your coil is good at around 4 ohms, then plug it all in, put a safety pin or whatever through the wire and check the voltage.

This is a long thread i have to find time to read it all , but in the meantime I'll trow this question in.
My ac is not working since last year first i checked the radiator fans both were not working so I changed them , now they are working.
Then I checked the sensor on the higj side it was good.
Then vacuum and refill the system
I'm looking at the compressor , the clutch is engaging .
Should i change the compressor ?

I would just plan on replacing the Refrigerant Control Valve, and maybe the filter/drier as well.

http://forums.tdiclub.com/showthread.php?t=283967&highlight=rcv

search on RCV for other threads.

DanG144 said:

I would just plan on replacing the Refrigerant Control Valve, and maybe the filter/drier as well.

http://forums.tdiclub.com/showthread.php?t=283967&highlight=rcv

search on RCV for other threads.

Click to expand...

It seems that to change the rcv valve I have to discharge the system.
I havea used compressor from junk yard if I have to discharge the system maybe its worth it to swap the compressor. .....what do you think ?
Is there anyway to test the rcv and see if its faulty ?

hhpeter said:

It seems that to change the rcv valve I have to discharge the system.
I havea used compressor from junk yard if I have to discharge the system maybe its worth it to swap the compressor. .....what do you think ?
Is there anyway to test the rcv and see if its faulty ?

Click to expand...

I would not use a junkyard compressor. If you have a sams club membership r134a cans are very cheap for a case of them. If it's the original ac compressor tho it can't hurt to change if you plan on keeping the car a long time. I have read of a lot of rcv going bad. Also don't forget to change the dryer/filter every time the system is open.

From reading many posts though if the compressor is pumping but you aren't getting cold air the rcv is likely the culprit. Did you change the dryer this past time? If not get one. This is a part where using a Napa branded part is fine. And it only costs around $20.

I agree with AnotherPerson, unless your compressor has either black oil, or metal particles visible in the oil, keep the one you have.

Very likely the RCV is bad in the junkyard compressor as well.

If a 'yard compressor has clear oil, spins easily, and has not been opened long enough to corrode inside, they can be fine - but the RCV is usually bad in them. I would not pay much for one, though.

I will be replacing my RCV either this year or next - the performance is degrading.

DanG144 said:

http://pics3.tdiclub.com/data/517/A4_Air_Conditioning_Troubleshooting_Rev_7.pdf on page 8 gives the approximate set points and mentions that the fans and clutch are both off on low pressure...I know this stuff is hard to get through. A technical writer, I am not.
The ambient temperature switch also kills the fans and compressor on low temperature...
Take your resistance reading with the battery cable off. If you have current flow through the ground path, then it will give high resistance readings...

Click to expand...

Ok, so I have around 105psi on both sides. About 56% on the pressure switch and the ambient sensor has continuity. The ground got way better after disconnecting the battery and is .1 ohms. The only other thing I've got going on now is 14/3 doesn't have 11 volts. I'm not sure how well versed you are in this wire being thay I'm reading diesels don't have throttle bodies. From what I can tell, this is a reference wire from the pcm that cuts the compressor at WOT or if the throttle body alignment is lost. Now I assume that if the throttle body alignment was out of wack then the car would run poorly which isn't the case. Anyone know if there is a way to bypass this wire to see if it is what's holding up the works? I don't have or know anyone with vcds

The two lines from the ECU are the ones I know the least about, unfortunately.

I think the voltage you have on that line may be normal, but I am not sure.

May I suggest that you rig it so that you can watch that voltage during engine startup with the AC on? Supposedly you should see that voltage be delayed after engine start for a couple of seconds...The ECU grounds that line to prevent the clutch from energizing.

http://pics.tdiclub.com/data/516/r134A_Properties.PNG

Your high pressure sensor (I have trouble calling it a switch, but when you buy one that is what they call it) is not reading correctly. It should be closer to 26% than 56%.

While it is reading less than the 64% that I found enabled my clutch to operate, I suspect that this is your issue. The data in those tables is so rough that I hesitated to publish it; I was watching pressure gauges and the sensor output with the fans failed off, then I watched it drop and noted the pressure and the sensor output. I was doing this single handedly with out any transducers or recording devices. And I only did it once as I was endangering my perfectly running AC system.

If you get new data from yours, please post it.