2011 air conditioning tied to outside air temp?

Our 2011 Jetta (4 door sedan) started having poor air conditioning late last summer. We assumed it needed a freon charge although was confusing as it seemed intermittent. We didn't bother getting it charged until after winter passed so had it charged this spring. But at that time we also started noticing some weirdness with the outside air temp sensor. It was intermittently erratic, working correctly some days but on other days showing wildly erroneous readings (usually ready way way colder than what it was outside). The AC charge didn't resolve the issue.



Eventually a clear pattern emerged - when the outside air temp display started reading very low then the AC output significantly declined. And now the radiator fan is on all time too. Is there some connection between the sensor and the AC? Are there some obvious (and hopefully cheap) things to check/service/replace to try and get working AC back? We sometimes have to transport our large dog and it can be unbearable on him when the AC craps out in hot weather.


***If this is going to get yanked because it isn't a TDI issue could someone tell me of a good, active form for Jetta issues?

I absolutely believe you're on the right path. I think it's time we got you hooked up with somebody in your area with VCDS. That's a special diagnostic computer for VW/Audi cars. With a 2011, I believe you'll be able to compare the values for the temperature sensors to that of known good values. This will help you not have to throw parts at it, but make an educated diagnosis. I'd get good values for you, but I don't have a a VCDS.

This is a good forum and somebody should chime in. Though, this particular sub-forum is a path less traveled. Search heavily in the Golf sub-forum, you might find a similar issue and the cars will be more or less the same from year to year with regards to HVAC.

http://forums.tdiclub.com/forumdisplay.php?f=81

Good luck sir.

It took me a long time to start to address this as I had no idea air conditioning performance was tied to any outside air temp sensing.

What are the relevant readings I should focus on if I can find a friend with one of these devices?

Find out where the outside air temperature sensor is, and check the wiring connections between that and wherever it leads to. (I'm actually having the same issue with my current car, which is not a VW. I know where the sensor is, it just hasn't been a priority to fix it)

Google suggests that the temp sensor is underneath/behind the front bumper towards the left side of the car, just in front of the radiator. First thing to do is to simply find the sensor and unplug it, clean the connector pins, and plug it in again.