Day & Night
Outdoor Contactor or Control Circuit Failure
Outdoor unit will not start at all; indoor blower runs and thermostat calls for cooling
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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 coil, Burnt contactor contacts, Broken low-voltage wire to contactor, Blown low-voltage fuse on indoor board
How to Fix / Troubleshooting
Safety first: Turn OFF power at the outdoor disconnect and indoor breaker. The contactor carries high voltage.
- Step 1 – Listen for contactor click: With the system calling for cooling, you should hear a click at the outdoor unit. No click suggests no 24V to the contactor or a bad coil.
- Step 2 – Inspect contactor: Remove the service panel and visually inspect the contactor. Look for pitted or burnt contacts.
- Step 3 – Check low-voltage wires: Ensure the two small wires on the contactor coil are secure and not broken.
- Step 4 – Replace contactor if burnt: If contacts are badly pitted or the coil is open (tested by a qualified person), replace with a compatible Day & Night contactor.
- Step 5 – Check indoor fuse: If there is no 24V at the contactor, inspect the low-voltage fuse on the indoor board.
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Repair Difficulty
Medium
3/5
Required Part
Outdoor Contactor
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