I got a call at the end of the day today that their Carrier 30HXC had tripped on T028 low oil flow. I got to site and discovered that their cooling tower water was at 50deg. I throttled back the water and started up the chiller and once the temp was back to normal I re established full flow. Chiller continued to run with good oil pressure (18#). Customer stated that he has seen the chiller start up with 50deg water before and manage to not trip. I am begining to wonder that maybe the issue is a combination of both cold water and maybe a fouling oil filter or 2. I looked breifly at the filter check out procedure and found that it was not very clear in the manual. Can anyone clarify the procedures to check both the external and internal oil filters?