Low DeltaT.

Trigger, action plan, and escalation criteria.

Related metric

cooling_delta_t

Trigger

(RAT − SAT) < threshold_min during cooling_mode (sustained)

Value drivers

Energy savings Asset lifespan Avoided truck rolls Customer experience

Preconditions

RAT and SAT sensors operational; cooling mode detectable.

Human role

Primary — dispatch decision and vendor coordination.

Action plan

(1) Sensor sanity check (RAT > SAT in plausible ranges). (2) Assess severity and duration (gradual = fouling or slow leak; sudden = compressor failure or coil freeze). (3) If Optimized-tier hardware is present, use compressor amps, refrigerant pressure, and outdoor air temperature to discriminate refrigerant loss vs compressor wear vs coil fouling. (4) Dispatch with the correct scope (filter, refrigerant gauges, coil cleaning).

Escalation

(1) DeltaT continues to degrade week-over-week → dispatch with refrigerant scope; refrigerant loss is more likely than compressor wear at this rate. (2) Sudden DeltaT drop with no prior trend → suspect compressor failure or coil freeze; dispatch immediately and notify the store. (3) Optimized-tier hardware confirms refrigerant pressure out of range → high-priority dispatch; vendor pre-staging required if site is rural. (4) Same RTU shows recurrent low DeltaT events after a maintenance visit → flag for replacement evaluation; repair is not holding.

Prevention

(1) Coil-cleaning cadence per site profile — annual for low-dust sites, biannual for high-load or open-floor sites; fouling is the most preventable cause of low ΔT. (2) Refrigerant-pressure baseline + monthly trend monitoring on Optimized-tier hardware — catches slow leaks weeks before ΔT crosses the floor. (3) Sensor calibration cadence (annual) on RAT and SAT — sensor drift silently biases ΔT downward and triggers false-positive low-ΔT alarms.