What happens
The delivered capacity, matched equipment or air distribution does not satisfy the evaluated demand.
Typical symptoms
Long runs with poor comfort, or new equipment that fails its approved commissioning checks.
Checks that distinguish this cause
Establish correct airflow, staging and charge first; compare the actual matched system and building load with the documented design.
What can look similar
Long operation near design conditions may be expected. A dirty coil can reduce a correctly selected unit's capacity.
Repair direction
Repair commissioning or delivery defects, or correct a proven selection mismatch using a validated design.
Verify the repair
Document matched components and verify performance against the intended design.
Equipment-specific limits
A comfort complaint alone is not a load calculation. Verify equipment performance and distribution before proposing a capacity change.
Practice this diagnosis
This cause is a reference topic; it does not yet have a dedicated simulated call. Browse the practice board.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- Carrier: HVAC installation and commissioning overviewSizing, airflow, charge and A2L installation considerations; obtain the exact unit manual.
Editorial review: 2026-09-29. Verify the current manual for the installed model.