Car sat all day in the snow and it was really icy today. I went for a 40 mile drive, when i got off the highway and was in stop and go traffic I heard the air pump turn on as normal but it was screeching like a loose alt. belt. I remember a few threads on a problem with the egr system and water building up in the pump. I'm assuming the water in the pump froze and is causing this noise.
Can anybody point me in the right direction? I always thought this was a M50 problem.

Queens NY
BMWCCA# 186796
86 325es (wrecked by careless driver)
87 325 300k (project for life)
00 540is 6spd 180k (daily driver)