Interesting BMW A/C inop due to bad cluster

Hopefully i'm not the only one that gets excited about fixing stuff.. I thought this one was interesting..

So its an 01 BMW 325i, customer complains A/C is not blowing cold, confirmed no compressor activation. Turned the compressor relay on with the scan tool, it kicked on and started blowing cold air. Read live data relevant to the A/C and found the ambient air temp sensor was reading -40F. Looking at a diagram i found the sensor goes directly to the instrument cluster, then that data is sent via CAN to the PCM. I tested the sensor, appeared to be functioning, checked for resistance/shorts, all good. I had .6v on one wire which was supposed to be a ground, and 3.4v on the other wire which was supposed to be 5v without the sensor in the loop. So i checked the power(s) and ground to the instrument cluster, all good. At this point i'm literally laughing out loud because an instrument cluster is keeping the A/C from working. Found a good used unit, slapped it in there and we now have a good ambient temp reading, and the a/c compressor kicks on again.

BMW clusters have caused me problems as well, the AC also gets a vehicle speed signal to turn off the cooling fan over 30mph.

Jake wrote: Hopefully i'm not the only one that gets excited about fixing stuff.. I thought this one was interesting..

So its an 01 BMW 325i, customer complains A/C is not blowing cold, confirmed no compressor activation. Turned the compressor relay on with the scan tool, it kicked on and started blowing cold air. Read live data relevant to the A/C and found the ambient air temp sensor was reading -40F. Looking at a diagram i found the sensor goes directly to the instrument cluster, then that data is sent via CAN to the PCM. I tested the sensor, appeared to be functioning, checked for resistance/shorts, all good. I had .6v on one wire which was supposed to be a ground, and 3.4v on the other wire which was supposed to be 5v without the sensor in the loop. So i checked the power(s) and ground to the instrument cluster, all good. At this point i'm literally laughing out loud because an instrument cluster is keeping the A/C from working. Found a good used unit, slapped it in there and we now have a good ambient temp reading, and the a/c compressor kicks on again.

Nice find!
The cluster certainly wouldn't have been at the top of my lists of suspects for that particular complaint.