If your Trane outdoor AC unit isn't running, first check that the thermostat is set to Cool with a temperature below the room reading. Then check for a power problem, a dirty filter, ice, or water near the indoor unit. If the outdoor unit hums without starting, or you smell burning, turn cooling off and call for service.
Check these before calling
- Confirm the thermostat settings. Use Cool and lower the set temperature. Allow the system's startup delay to finish. Replace thermostat batteries if your model uses them and shows a low battery warning.
- Look at the filter. Follow the manual to check an accessible filter. A clogged filter can restrict airflow and contribute to icing.
- Look for ice or water. Ice on visible piping or water around the indoor unit needs attention. Turn cooling off and contact an HVAC technician; don't chip ice away or bypass a drain safety switch.
- Note any loss of power. Tell the technician if this followed an outage or a tripped breaker. If you're unsure which circuit serves the unit, leave it alone. Don't open the outdoor disconnect or equipment panels.
What the symptom tells you
- Indoor fan runs, outdoor unit stays silent: power, controls, or an internal component could be at fault. The symptom doesn't identify one failed part.
- Outdoor unit hums but won't start: switch cooling off and book service. A capacitor or motor may be involved, but it needs testing.
- Breaker keeps tripping: stop resetting it. Have the fault checked.
- Fan spins but the house stays warm: see AC running but not cooling.
What to tell the technician
Have the model number ready if its label is safely accessible. Describe what runs, what stays silent, any noise or error message, and when the problem started. A short video can help capture an intermittent sound.
Leave capacitor tests, wiring, and refrigerant work to the technician. Turning the thermostat off doesn't make the inside of the outdoor unit safe to touch.