The temperature indicator below my speedometer reports -36F. The diagnostics in my climate control report the external air temperature sensor is open. The heater only works if set to HI, one step above 92. I've been told this is because the external air temperature sensor is defective or disconnected. Is this correct?

I've been told it's behind the front license plate, or near the towing hook, or near the right front brakes. I don't see anything with wiring in any of those places. Where is it? What does it look like, and how big is it? What color wires lead to it? It's not shown on the wiring diagrams I have for the climate control system.

 

On my 03 C230 it is alittle blackpointy thing, sort of like a model airplane's missle if you ever saw one,which hangs out in the small grille piece below the bumper. It's locatedto theleft of the license plate and to the right of the fog light on my car. This,as you are looking at the carfrom the front.

In my case, it get knocked out by accidently bumping a snowbank. In your case, maybe the wire got disconnected?

Anyway - I know my car is newer model than yours, but I cannot think they changed it that much over 4 years.

Hope it helps...

 

Thanks for the advice.

On my 1999 C280, I found some snipped-off wires on the left, beside an air conditioner part that looks vaguely like an oil filter. One green, one brown. When I run the climate control value displays (set to 72f, hold REST for 5 seconds, push FAN to advance between measurements), measurement number 2, which is the external air temperature sensor, says OPE. I shorted the snipped-off wires and it says CLO. So I need to buy an external air temperature sensor and figure out where it ought to be mounted.