RTU Not Cooling
A tenant space is warming while the rooftop unit runs with no alarm. Read the split, then indoor airflow, then heat rejection — charge last.
Scenario briefing
The call
A facility manager reports the rooftop packaged unit serving a retail space is running but not cooling. Fans and compressor activity are audible on the roof, yet supply air is not cold and the space temperature is climbing through the afternoon.
There is no alarm or fault code on the thermostat or the unit control. Staff have already set the thermostat lower with no change.
Work the sequence: confirm the complaint with temperatures, split indoor airflow from the outdoor section, then inspect and test the high-probability items. Refrigerant is the last conversation, not the first.
Step 0 · Required
Safety Gate
Confirm every item below before the diagnostic area unlocks. This mirrors the pre-work checklist you owe every customer.
0 of 5 confirmed.
Step 1 · First checks
LockedDiagnostic decision
You are on the roof with the unit running and the space warming below. What do you do first?
Complete the safety gate to continue.
Component view
Rooftop packaged unit — component view
Interactive schematic coming in the next release
Select a component above to read what it does and how it fails on this call.
Progress
Step 1 of 4
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