Carrier
Outdoor Unit Non-Start
Carrier air conditioner indoor unit runs but outdoor unit does not start
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed contactor or relay, Open high-pressure or low-pressure switch, Faulty outdoor PCB, Broken communication between indoor and outdoor
How to Fix / Troubleshooting
Safety: High voltage present. Turn OFF power at the disconnect and breaker before opening the outdoor unit.
- Step 1 – Listen for outdoor unit: When cooling is called, check if you hear any click or hum from the outdoor unit.
- Step 2 – Check disconnect: Ensure the outdoor disconnect is ON and properly seated.
- Step 3 – Visual inspection: Open the control panel and look for burnt contactor contacts, loose wires, or blown fuses (if present).
- Step 4 – Technician diagnosis: A technician should test the contactor coil, pressure switches, and PCB outputs to determine why the outdoor unit is not starting.
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Repair Difficulty
Hard
4/5
Required Part
Contactor / Outdoor Relay
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