DIY overhaul AC?

300D · Jun 19, 2020

pedroYUL said:
Last on my hijack...I had the wrong error code, I do not have error P2612. I was been lazy, taking my tunning box error C0A34 and converting to P...

from here https://forums.tdiclub.com/showthread.php?p=4464392

But that translation did not work in my case. Once I connected VCDS it was obvious.

Now, my AC still doesn't engage. Fans check out themselves, and if I connect pins 1-2 from the radiator thermoswitch connector I do get low speed on both, but nothing when I connect pins 2-3 with the key on. I checked all fuses, both on top of the battery, and inside (5,16,25). Also, I have new FCM and blower resistor pack.

Did I get a DOA FCM?

Have you gone through the AC Troubleshoot document? It is pretty detailed. Led me to find that the voltage is not getting through my T14 connector. It arrives, and then doesn't make it through in two pins. The always on /4, and the switched /9.

Maybe a wiring issue on yours as well?

pedroYUL · Jun 19, 2020

FCM is indeed DOA. Resistance does not check out. Thank you 300D!

300D · Jun 26, 2020

I am trying to order the pieces to fix up this T14 connector. Does anyone know which terminal ends the connector uses? Are they all the same size? I would rather not dig it out of my car before having all the pieces to put it back together fixed.
This is the connector which I am ordering from ECSTuning:

Are they all this? https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/small-terminal-priced-each/n10335807/
And there are no junkyards near me. I figure this way will be easier and cleaner. Thanks.

300D · Jun 27, 2020

Nobody knows which pins are used in this connector?

ToxicDoc · Jun 27, 2020

if you put the connector number in Google, then press the images tab, you can see several examples of the square-shaped terminals with the connector. Haven't come across the terminal # yet, but it was only a cursory look

wonneber · Jun 27, 2020

300D said:
Nobody knows which pins are used in this connector?

I would say all the ones on the old plug are used.

Is the car manual air or climate control?

300D · Jun 29, 2020

wonneber said:
I would say all the ones on the old plug are used.
Is the car manual air or climate control?

Not 'used' as in whether or not the slot is used on the connector(the AC troubleshoot identifies every wire in the connector), but which vw pin connector part is IN the connector.

For example, is it this one: https://www.idparts.com/connector-thin-pinthin-gauge-n10335807-p-3710.html

Or another one? I am hoping it's that one as I ordered those.

pedroYUL · Jun 30, 2020

Are you positive your issue are the connectors?

In my case one of the T4 wires was split open, and I don't know how come I didn't see it before.

Have you peeled some of the tape back and checked for glaring wire abnormalities? I could see how the wire I repaired was internally broken (corrosion?) first.

300D · Jun 30, 2020

pedroYUL said:
Are you positive your issue are the connectors?

In my case one of the T4 wires was split open, and I don't know how come I didn't see it before.

Have you peeled some of the tape back and checked for glaring wire abnormalities? I could see how the wire I repaired was internally broken (corrosion?) first.

Yes. I am positive. 12v at the wire just before the T14, less than a volt at the pin connector. This, I of course found out only after pealing everything else away.

Plus, lots of green corrosion(verdigris) evident.

Hoping to tackle this tomorrow, but probably next week after the weekend.

pedroYUL · Jun 30, 2020

I just had to go myself to a boneyard 1h away to search for another FCM, just to discard anything else, so I feel your pain of not having that option.

I actually read about your connector right after I came back from the yard, otherwise I would've cut one for ya.

I do want to make clear here too (I also did in my own thread), that my fan control module (FCM) was perfectly fine. The new one I bought was fine, the replacement was good too, and even the one I bought at the yard.

Resistance over the different combinations in the T4 connector is not an indication on the status of the FCM. Someone published their experience with these resistances, but the conclusion is not correct.

This person claims that pins 1-2, 1-3, 2-3, should have some resistance and not been infinity (open), but the bone yard FCM has all combinations open and it works perfectly. Also, 2 new FCM (Striebel brand) have all combinations open, except 3-4 at 254 kOhm. Also, all of the FCM I tried at the bone yard (tried like 5) read all open except 3-4 at 254 kOhm.

300D · Jun 30, 2020

pedroYUL said:
I just had to go myself to a boneyard 1h away to search for another FCM, just to discard anything else, so I feel your pain of not having that option.

I actually read about your connector right after I came back from the yard, otherwise I would've cut one for ya.

I do want to make clear here too (I also did in my own thread), that my fan control module (FCM) was perfectly fine. The new one I bought was fine, the replacement was good too, and even the one I bought at the yard.

Resistance over the different combinations in the T4 connector is not an indication on the status of the FCM. Someone published their experience with these resistances, but the conclusion is not correct.

This person claims that pins 1-2, 1-3, 2-3, should have some resistance and not been infinity (open), but the bone yard FCM has all combinations open and it works perfectly. Also, 2 new FCM (Striebel brand) have all combinations open, except 3-4 at 254 kOhm. Also, all of the FCM I tried at the bone yard (tried like 5) read all open except 3-4 at 254 kOhm.

You are looking at these documents, correct? http://forums.tdiclub.com/showthread.php?t=242699

My issue (so far) is that the power coming into the FCM is not correct. The T14 connector and corresponding internal pins are corroded. This may not be my only problem, but it most certainly is a current problem. My pressure sensor tests ok, the fans are new, the FCM is new, the ambient sensor test ok, the T4 connector tests ok, and continuities seem to test ok(at the moment).

pedroYUL · Jun 30, 2020

Yes, I looked at all that, but still wasn't clear to me how to make sure your FCM works or not.

I was looking at https://www.myturbodiesel.com/threa...n-ac-compressor-clutch-and-coil-removal.6651/

In that thread there is a resistance test for the FCM that is not right. I guess I suspected my FCM since everybody says they are a common issue, but it turn out to be a simple wire. The red wire in my T4 connector was internally corroded until the insulation split.

300D · Jul 8, 2020

Update.

4 of the wires going into the T14 at the FCM were corroded/broken.

Couldn’t get the remaining pin bits neatly out of the connector, along with the pink slide lock breaking upon removal, so have ordered a new connector from ECS tuning.

Also can confirm a few part numbers:

The pins by themselves are part #: N10335807 But these things are tiny and require a specific open barrel crimper that I don’t have.

VW repair wire 000979131EA is what I am going to use. Not the exact wire size for the two different wire dimensions going into the connector, but the right sized pins, and will solder in just fine. No little seal, but a dab of sealant will suffice.

At this rate my AC should be fixed by the fall...

300D · Jul 14, 2020

Another update:

WORKING AC!!!

Finally got the new connector from ECS Tuning (man, their shipping is slow). Spliced in the four VW repair wires with solder and heat shrink. Wrapped with loom tape, connected in, and then put battery back together. Started with the ignition on and AC on and fan on 1, and I had working fans for the first time in my ownership! Started her up and ran the AC, and it blew nice and cold!!

Anyone know what the temp at vents should be? Temp outside is 70 degree temps, just running at idle? On fan speed 1, no recirculation, and at idle it was 41, measured using an infrared thermometer pointed at the vent fins.

I will get some gauges on it to double check pressures, but it seems to be working like a champ!

Some nice AC will go well now that the passenger side window is taped up as it dropped just yesterday. Doh.

Genesis · Jul 14, 2020

Those temps are good; 41F is right about where you'd expect given you're not at the coil itself, some warming takes place in the ducts, and you DO NOT want the coil to freeze!

300D · Jul 14, 2020

Genesis said:
Those temps are good; 41F is right about where you'd expect given you're not at the coil itself, some warming takes place in the ducts, and you DO NOT want the coil to freeze!

Excellent. I put in just about the exact amount measured in grams. Just a little bit under as I was putting it in a few weeks ago when before the system even ran. It was when I had replaced everything and was loading it in expecting it to turn on. System didn't turn on but I still managed to get most of it in using warm water.

ToxicDoc · Jul 14, 2020

Check temperatures at high speed. Your temperature looks good for a start, about a 30 degree reduction. You never want it much lower than 40 F or you will risk freezing the evaporator.

DIY overhaul AC?

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