Indoor unit blows air but supply temperature is near room temperature. Common on residential splits.
1
Dirty / iced evaporator coil
medCheckPull filter; inspect coil with flashlight. Look for ice on suction line at air handler.
FixThaw fully (fan-only 1–3 hr). Replace filter. Clean coil with no-rinse evap cleaner.
ToolsFlashlight · Coil cleaner · MERV 8–11 filter
2
Low refrigerant charge / leak
highCheckMeasure superheat and subcool with gauges. Low subcool + high superheat = undercharged.
FixLeak-search with electronic detector or UV dye; recover, repair, evacuate, weigh in factory charge.
ToolsManifold set · Leak detector · Micron gauge · Recovery machine
SafetyEPA 608 certification required to handle refrigerant.
3
Outdoor condenser coil clogged
lowCheckLook at outdoor coil — cottonwood, grass, dryer lint. Measure liquid line temp vs ambient.
FixPower off, rinse coil from inside out with garden hose (no pressure washer).
ToolsGarden hose · Fin comb
4
Condenser fan motor not running
highCheckListen at outdoor unit. Compressor on, fan off → motor or capacitor.
FixTest dual-run capacitor (fan section). Replace if out of ±6%. If cap is good, replace fan motor.
ToolsCapacitance meter · Multimeter
SafetyDischarge capacitor before handling — stored energy can shock.
5
Thermostat or wiring fault
lowCheckVerify call for cool at Y terminal (24 V to C). Check for tripped float switch on condensate.
FixReset float switch, clear condensate line, replace thermostat batteries / wiring.
ToolsMultimeter
Safety
Pull the disconnect and lock out before opening HVAC equipment. Discharge dual-run capacitors before handling. Refrigerant recovery and brazing require EPA 608 certification and proper PPE.