E46 - OAT Climbs ONLY when AC is ON

821 Views 6 Replies 6 Participants Last post by alpinweiss, Jun 5, 2020

looyvillelarry

Discussion Starter · May 9, 2020

I've searched quite a few OAT issues, but never have I found this one.

If the AC is off, all is well. The OAT registers properly. The minute I turn the AC on, it starts climbing about 2*F a minute !, even at highway speeds. This is the OAT, NOT the coolant temp !

If I turn the AC off, it will fall (slower)..

I've never had the AC on in this car and was preparing for summer.

Any ideas about what could be causing this ?

TIA

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alpinweiss

· #7 · Jun 5, 2020

Fast Bob said:
Let me guess....you found the OAT sensor dangling by a wire under the driver`s side A-frame ?

The E46 OAT sensor is definitely located in a vulnerable place.

On my E90, they solved this problem by putting the OAT sensor much higher and in the center behind the front bumper. So is this better? Absolutely not! My OAT sensor failed, and I had to remove the entire front bumper cover to get access and replace that sensor.

:drive:

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