2001 Audi A4 Misreading outside temperature sensor

MANGOON

MEMBER
2001 AUDI A4
4 CYL
AWD
AUTOMATIC
130,000 MILES

I've replaced my outside temperature sensor (twice in 2 weeks after having no luck with the first replacement). The problem is that intermittently my temperature reading on the instrument cluster reads -45 degrees. Trouble is, when this happens, the A/C "thinks" that it's plenty cold outside and all I get in blasting hot Arizona heat coming into the cabin. I'm convinced that the sensor is working correctly, so now I am wondering if something is faulty within the instrument cluster itself. As near as I can determine, the wiring is essentially outside temp sensor --> instrument cluster --> A/C (as an overide). Any ideas?

Thanks.

2 Replies

FBETTOBR

MEMBER
3 POSTS

Hi mangoon,

You are experiencing an open-circuit issue. What's happen is that when the sensor signal is lost due a broken wire or misconected socket, the temperature indication drops to the minimals. It's because the caracteristic of this kind of sender (NTC - as low the temp, as upper is the resistance of the ceramic sensor inside the sensor).
Check the sender's wire circuit for continuity with a multimeter. A tip: if the signal is ok, check again but bending and turnig the wires, to find some invisibles brokens wires. Do not forget to check the conectors.
Greetings.