Rheem Rheem Classic Series RA16 3-Ton 16 SEER Central Air Conditioner NOT COOLING Error Fix: AC Not Cooling — Outdoor Unit Running

Error code NOT COOLING on the Rheem Rheem Classic Series RA16 3-Ton 16 SEER Central Air Conditioner means: AC Not Cooling — Outdoor Unit Running. The outdoor condenser unit is operating (you can hear the compressor humming and the fan spinning) but the air coming from the indoor vents is not cold or not cold enough. Rheem central AC condensers like the RA16 series are outdoor-only units with NO display and NO error code system — all diagnostics require physical inspection and measurement. Most common cause: low refrigerant charge due to a leak in the system. Rheem RA16 units use R-410A refrigerant, which does not deplete on its own — if the charge is low, there IS a leak somewhere in the system (evaporator coil, condenser coil, line set fittings, service valve cores). A licensed HVAC technician must locate and repair the leak, then recharge the system to the nameplate specification. Other causes: a dirty indoor evaporator coil restricting heat absorption, a dirty outdoor condenser coil restricting heat rejection (wash with a garden hose — gentle spray, not pressure washer), or a failed metering device (TXV or piston).

The most successful fix is "Diagnose and Repair Refrigerant Leak or Replace Metering Device" (hard difficulty, ~120 minutes). This fix costs nothing. HomeMD has 2 community-ranked fixes for this error.

This error is rated warning severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Diagnose and Repair Refrigerant Leak or Replace Metering Device") is rated hard difficulty and takes about 120 minutes. Tools needed: HVAC manifold gauge set, Electronic leak detector, Refrigerant recovery machine.

DIY cost: $0. Professional repair typically costs $350-$600. Many homeowners save money by trying the top-ranked community fix first.

The Rheem Rheem Classic Series RA16 3-Ton 16 SEER Central Air Conditioner has 7 other known error codes, including: CAPACITOR FAIL (Run/Start Capacitor Failure), CONTACTOR FAIL (Contactor Failure or Pitting), FAN MOTOR FAIL (Condenser Fan Motor Failure), FREEZING UP (Evaporator Coil Freezing — Ice on Refrigerant Lines), NOT STARTING (Outdoor Unit Won't Start), and 2 more.