Capacitor Repair
A capacitor helps the compressor or fan motor start and, on many systems, run. A hum alone does not prove that the capacitor is bad: a motor that draws too much current or a failed control can produce similar symptoms. Identifying the connected load matters because replacing a capacitor without finding a stressed motor may leave the original problem unresolved.
One symptom.
Several possible causes.
What causes this?
These are possibilities, not a diagnosis. Similar symptoms can come from different parts of the cooling system.
A start or run capacitor can lose capacitance with age or heat, leaving its connected motor unable to start reliably.
A fan motor or compressor with excessive current draw can mimic capacitor failure or contribute to repeated capacitor trouble.
A faulty contactor, loose connection, or lack of supply voltage may keep the outdoor components from receiving proper power.
What to look for
Take note of when the problem occurs and what the indoor and outdoor units are doing. Share these clues when you call.
- 01
The outdoor unit hums but its fan or compressor does not start when cooling is requested.
- 02
The system tries to start, shuts off, and tries again while indoor airflow continues.
- 03
Cooling becomes intermittent or the outdoor unit stops after running briefly.
Capacitors can retain a dangerous electrical charge even when the disconnect is off. Do not open the outdoor cabinet or attempt to discharge or replace one yourself.
What our technician will do
A technician tests the start and run components and checks for an underlying motor problem before replacing a failed capacitor. The findings help determine which repair, if any, addresses the actual fault. Repair pricing is quoted after diagnosis; review the proposed work and price before approving a repair.
With power made safe, inspect the capacitor and connections and measure capacitance against the equipment's rated value.
Check the affected motor's electrical readings and starting behavior, plus control and supply conditions, to identify whether the capacitor is the cause or a symptom.
Explain findings and obtain approval before replacing a failed part or recommending additional motor work.
If a repair is performed, verify the outdoor unit starts and runs normally and that the affected motor's operating readings are appropriate.
What to tell us when you call
- Is your AC blowing warm air or no air?
- Is the outdoor unit running?
- When did the problem start?
- Have you noticed unusual noises, ice, or leaking water?
These details help our technician prepare. You don’t need to diagnose the problem yourself.
Need help with your AC?
Tell us what you've noticed at home. Scheduling depends on your address and the current appointment schedule; contact us to discuss the next step.