ok my ac wont go cold i cant here the compressor tunr on or anything my ? though is on the obc if my ext temp says its -35F would this stop my a/c from coming on or would it be something else new to bmw so any info would be great thank you also this is on a 96 328is thanks

also i have checked the fuses but not sure on how to know if the relay may be bad or not anyone know how to test a relay please let me know

OBC readout does not interface with climate control. That is likely a bad or disconnected temp sensor. It is located in the brake cooling duct (right side I think).

AC issue could be electrical, fuses, relays. Or low refrigerant pressure which would trigger the low pressure cutout switch. Low pressure = leak. A quick recharge will get the system back running, if refrigerant charge has been totally lost, the system will require a full evacuation, leak test/repair, recharge.