The compressors on these make noise as they age, it will make a knocking noise. Anytime you cut the snowflake on or defrost, it'll come on. It's usually overlooked, but new coolant oil will help it to last longer and keep quieter.

__________________
740iLDUKE
01' DINAN 7 S62 Swap - Stratus Grau
(1587 produced in SG 440)
02' 4.6is DINAN X5 S2 Supercharged
833/3258 produced | 1/27 Dinan X5's