HVAC/R AI Pro
Cooling diagnostics
HVAC Field Guide
AC not cooling but the fan is running?
When an air conditioner runs without cooling, the issue usually sits somewhere between airflow, refrigeration performance, controls, and the outdoor unit. Here is how trained HVAC techs narrow it down in the field.
Field workflow
What this guide covers.
If your AC is not cooling but the fan is running, this guide explains common causes and how HVAC technicians diagnose the issue.
Start with the symptom
A running fan means the system is moving air, but it does not prove the refrigeration cycle is doing its job. Check whether the outdoor unit is running, whether the coil is freezing, and whether airflow is restricted before assuming one cause.
Common causes
Low refrigerant, dirty condenser coils, frozen evaporator coils, weak compressors, blocked filters, duct restrictions, and thermostat or control issues can all leave the fan running while cooling drops off.
Field diagnosis
Technicians usually verify airflow and static pressure, inspect coils, check electrical components, and compare superheat or subcooling readings before recommending a repair.
Connect the next step
HVAC/R AI Pro helps keep troubleshooting notes, airflow checks, photos, and estimate guidance connected so the recommendation stays tied to the actual diagnosis.