Odd HVAC problem

[m73m95]

Hey all,

So, when I first start my car, I get no response from the HVAC. No fan, no AC. It doesn't matter if I set it on "auto", or if I adjust doors/temp/fan manually, nothing happens. Then, after a few min, I get everything back again. Cold AC, doors move, fan goes to high. The problem is also intermittent, which makes it a bitch to diagnose. Sometimes it comes on immediately after I start the car, other times, nothing. It only seems to do it when it's hot outside (80+). It started to do it at the end of last summer, but then worked fine all through the winter. Now that it's getting warm out again, it's started again...

I've found on a few VW forums that some people have changed out the RCV on the AC compressor, but I'm not sure their problem mirrors mine. They complain of no cold air for the first few min of driving... I don't have cold air, because I have no fan. Would the AC compressor not coming on also stop the interior fan from coming on?

Anybody else have similar issues?

[bakedziti]

Do you have VAGCOM or Carista? The codes would help you pinpoint it. Honestly, it sounds like your blower motor resistor may be the culprit. Ironically, my blower motor/resistor stopped working last week. All the lights work, and you can feel the AC compressor kick in when enabled, but nothing comes out of the vents. Thankfully my heated seats still work, because we got some late snow this past weekend. I suggest looking for a part out for the blower motor/resistor, because they can be pricey; non-OEM replacements aren't as much. There is a guy in the S4 section with a part out that will likely work for you.

[m73m95]

Yeah, when searching for the resistor, those sound much more like my symptoms.

Thank you Baked!

[valida4]

I had this problem a few months ago. I replaced the fan blower and that fixed it. The blower motor/resistor come together. Just bought a used unit off eBay for around $58 including shipping.

[dbv2]

If you still have warranty this is covered :)

[van462]

I had intermitted fan issues. I pulled the blower motor after I did a resistance check across the terminals and saw that it was too high. I then flushed the motor with isopropyl alcohol and put a drop of oil on the bearings. Has been fine for the last 4 months

[m73m95]

If you still have warranty this is covered :)

My car has 147k miles I am quite safely out of warranty.

I had intermitted fan issues. I pulled the blower motor after I did a resistance check across the terminals and saw that it was too high. I then flushed the motor with isopropyl alcohol and put a drop of oil on the bearings. Has been fine for the last 4 months

Yeah, I'll refurb the motor when I have it all out. When the fan works, it works very well, so I'm hoping the resistor, alone, will cure this

I put Linux on my laptop, and am having trouble getting VCDS to run in WINE (Anybody know how to help with that?? LOL)...so I can't diagnose this properly, yet. I found a resistor on Ebay, so I'll throw it in. If that doesn't work, then I'll have to get the laptop up and working.

[van462]

If you have a multimeter you can check it fairly easily. You can sneak the meter probes into the back on the connector coming from the controller to the fan. With the car off and checking ohms it should read around 8 ohms. Switch to voltage ad press the key to turn on accessory. With the fan speed set to the highest it will be 12 volts and you can watch the voltage drop as you choose lower settings. When I wigged the wires going to the fan I noticed my ohm values jump around a lot. I figured the brushes in the motor weren't making good contact.

[m73m95]

Perfect. Thank you Van!

[KompressorLOgic]

^ mines starting to do the same periodicly, seems to be on hot days, after the car has sat in the sun for a while!