Possible resistor issue for my TDI fan?

Hello all,

I'm new to the board and was hoping some of the more mechanically inclined TDI owners could help point me in the right direction. My 2014 TDI fan has been having issues and I'm becoming increasingly frustated. When idling, the fan will run all day at any setting. However, whenever I drive 15+ minutes, the fan output slowly decreases to the point no air comes out. Occasionally, the airflow will return to normal when I put it back in park, but other times not. You can hear the motor running, but it's as if something is blocking the airflow. This happens with and without running the A/C. I've noticed the issue occurs more frequently with speeds 1-3, although 4-6 are not immune. I've seen other's on the forum identify resistor issues, but typically in their case the fan does not work at all at the lower speeds.

The dealership ran some tests and had no codes pop up during diagnostics, and of course they never drove the vehicle to try and replicate the issue. They convinced me it was the fan motor and (regrettably) I shelled out money to have it replaced, but alas the problem continues. I was wondering if any TDI owners could help me identify a possible source to my conundrum? Some of the other threads mention possible resistor issues and fan switches, but I'm not sure how to tell for certain if it's one of these issues. As of now, my car is rather useless on long road trips as no air = hot ride.

Thanks in advance for all your help

send me your e-mail the schematics

Your evaporator is freezing up . . . likely the RCV or it's controls are stuck or goofy, causing it to overcool and freeze the condensate into a solid block of ice. I bet if you run the fan with AV off, you will get airflow back in short order.

tadawson said:

Your evaporator is freezing up . . . likely the RCV or it's controls are stuck or goofy, causing it to overcool and freeze the condensate into a solid block of ice. I bet if you run the fan with AV off, you will get airflow back in short order.

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I took it for an hour drive last night without running the AC and the air output still kicked the bucket after ~10 min. After I returned home, I flipped the setting back to max and after a few seconds it was back to normal. This would rule out the evaporator, right?

you need to find someone with a VCDS and figure out what is happening.

osbeckc said:

I took it for an hour drive last night without running the AC and the air output still kicked the bucket after ~10 min. After I returned home, I flipped the setting back to max and after a few seconds it was back to normal. This would rule out the evaporator, right?

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Yup, that would rule it out. It's a more confusing issue now, since your description was dead on for a freezeup, and the new blower motor rules out motor overheating and bearings binding as well . . . Not sure if the Passat uses a resistor or an electroinc contol, but if the latter, that would be my next guess . . . if it is a resistor, I'd have to see it to comment more, since tne resistor isn't used on high . . .

- Tim

tadawson said:

Yup, that would rule it out. It's a more confusing issue now, since your description was dead on for a freezeup, and the new blower motor rules out motor overheating and bearings binding as well . . . Not sure if the Passat uses a resistor or an electroinc contol, but if the latter, that would be my next guess . . . if it is a resistor, I'd have to see it to comment more, since tne resistor isn't used on high . . .

- Tim

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The strange thing is after the motor was replaced, I took it back to the dealership when the problem started happening again. The mechanics began playing around with the cover to the fan and removed a plastic cover. Once they removed this piece (not sure the name but it's on the passenger side of the engine) you could feel the air start kicking out again. After reading more of these threads I'm starting to think there's a blockage or something which is restricting the air, as opposed to a resistor or other mechanical issue. The mechanics offered to continue looking but we're going to bill me the hours to take apart the dash. Thankfully you guys have been a good help so I can possibly narrow it down before going on a wild goose chase

That's why I said freezeup . . . it's a blockage that builds up in time running AC . . . And don't they have one of those snake cameras like you can get at Home Depot, that will let them look inside all the ducting without dissecting the dash? Oh, and I assume they have checked tha cabin air filter? Oh, and any difference between recirculate and not recirculate?

tadawson said:

That's why I said freezeup . . . it's a blockage that builds up in time running AC . . . And don't they have one of those snake cameras like you can get at Home Depot, that will let them look inside all the ducting without dissecting the dash? Oh, and I assume they have checked tha cabin air filter? Oh, and any difference between recirculate and not recirculate?

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I did have them replace the air cabin filter. While it definitely needed cleaning, it doesn't appear to be the source of the issue. I did play around with the recirculation yesterday. Doesn't initially affect the air output, but once the air dies down the recirculation is definitely louder despite no air coming out. I did manage to find a local tdi guy near me, so I'm hoping he'll take the time to go over the car with me. The dealership gave me the impression if the issue doesn't occur within 5 minutes they weren't going to spend the time pursuing it.

I have this exact issue with my 2014 Passat. Did you ever resolve the problem? I've heard of a few instances of this problem but no clear fix. Anybody else out there have any experience?

The various hvac functions are performed by various flaps operated with small stall motors running pinion gears along a quadrant. Do all the various air direction functions operate as they should? You could try running through the the various functions repeatedly when this fault starts occuring. The flap doors have foam edge seals which can stick. You didn't say if it was an se or sel.