AC Tune up for Watson Dormitory. Air handler has (6) 16x20x2 MERV 13 filters which should be replaced. Cleaned drain with C02. Discussed filter situation with a Mike DeFrank. He will replace MERV 13 filters which are being used while students are residing in dormitories as a COVID 13 measurement. Thermostats/controls are programmed/monitored by Corey. Talked with dorm manager Earl who informed me that error code E3 has been displayed for some time on minisplit thermostats. According to Trane literature E3 is a low pressure cutoff. Earl said another contactor possibly charged system when error code E3 appeared the first time. We will reschedule to investigate/find solution to low pressure problem.