What does AHU-FC02 mean?
MAT is colder than both the outdoor air and the return air — physically impossible without a sensor or damper fault.
Why does it matter?
Strong indicator of MAT sensor in a cooling-coil discharge stream (mis-located sensor), stratified mixing, or sensor calibration failure. Every SAT control loop downstream is acting on bad data.
What should you do?
Inspect MAT sensor placement — it should be downstream of the mixing plenum but upstream of the cooling coil. Verify against OAT and RAT calibration. Look for upstream coil bypass.
This is a diagnostic rule: Energy Agent surfaces and ranks it as a data quality problem and claims no dollar savings for it, by design.
How Energy Agent prices a finding
Written by Pelorus Engineering · Brent Waluzak, P.E. (FL), President, Pelorus EngineeringLast updated