2001 Audi A4 Misreading outside temperature sensor

2001 AUDI A4
130,000 MILES • 4 CYL • AWD • AUTOMATIC
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MANGOON
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  • 2 POSTS
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.
Apr 30, 2009 at 8:42 PM
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FBETTOBR
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  • 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.
May 27, 2009 at 9:26 PM
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MANGOON
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Thanks. I'll give that a try. We've checked the circuit before, but will try again. The logic at least makes sense as to why we are seeing the "reset." Often times, however, when this does occur (which is not all the time), turning the car off for 5 minutes and then restarting it fixes the issue. Does that still make sense? I really do appreciate the insight.
May 28, 2009 at 11:01 AM
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