The common signs are the outdoor fan not spinning, a humming unit that will not start, ice on the refrigerant lines, warm air from the vents while the system runs, and a breaker that keeps tripping. Several of these mean shut the system off rather than keep running it.
The Fan Is Not Spinning
If you hear the outdoor unit humming but the fan blade is stationary, that is usually a failed capacitor or fan motor.
Turn the system off. A compressor running without the condenser fan overheats quickly, and this is one of the fastest ways a small part failure becomes a compressor replacement.
Capacitors are the most common condenser failure by a wide margin. The part is inexpensive; what it destroys when ignored is not.
Ice on the Lines
Ice on the refrigerant lines or the outdoor unit always means a problem — either restricted airflow indoors or low refrigerant charge.
Shut the system off and let it thaw rather than continuing to run. Running with a frozen coil risks sending liquid refrigerant back to the compressor, which converts an airflow problem into a system replacement.
Check your air filter while it thaws. A clogged filter is the single most common cause.
The System Runs but the Air Is Not Cold
If the blower is moving air and the outdoor unit is running, but the supply air is barely cool, the likely causes are low refrigerant or a compressor that has lost capacity.
Low charge means a leak, because refrigerant is not consumed. Adding more without finding the leak is a delay, not a repair — and running low is the leading cause of premature compressor failure.
The Breaker Keeps Tripping
Reset it once. If it trips again, stop.
A breaker is responding to a real electrical condition — a shorted compressor winding, a failing motor drawing excessive current, or a wiring fault. Repeatedly resetting it is how an electrical problem becomes a fire risk.
Noises Worth Diagnosing
Grinding or screeching generally means bearings in the fan motor.
A hard clunk on startup or shutdown suggests a mounting problem or compressor issue.
A loud buzzing that was not there before often points to a contactor that is pitting and chattering.
Any hissing near the unit can indicate a refrigerant leak under pressure, which is worth prompt attention.
Short Cycling and Long Runs
A unit that starts and stops every few minutes is short cycling, which indicates a refrigerant problem, a failing control, restricted airflow, or an oversized system. It is hard on the compressor and prevents proper dehumidification.
The opposite — running continuously without reaching setpoint — means the system has lost capacity or the load has increased. Some continuous running on a hundred-degree Hill Country afternoon is normal. At nine in the evening in October it is not.
Rising Bills
Not every symptom is dramatic. A condenser coil packed with cottonwood, grass clippings, and dust cannot reject heat, so the compressor works against elevated head pressure every hour it runs.
That produces no noise and no comfort complaint until it produces a failure. It shows up on the electric bill first, gradually enough that households acclimate to it.
What You Can Check Safely
Confirm the breaker has not tripped. Look at the outdoor coil — if it is visibly packed with debris, you can rinse it gently with a garden hose from the inside out, with the power off at the disconnect. Never use a pressure washer; it flattens the fins permanently.
Clear vegetation to at least two feet on all sides.
Beyond that, condensers contain high-voltage components and capacitors that hold a charge after power is removed. Leave them alone.
Repair or Replace
Capacitors, contactors, fan motors, and accessible leaks are worth repairing on a reasonably young system. Compressor failure on an out-of-warranty unit past twelve years usually points toward replacement.
Most of these failures are found in advance during AC maintenance, where capacitors are measured rather than eyeballed. Details are on our AC condenser page.
For emergency AC repair, call (830) 240-1835 or contact 72 Degrees.
