Fraser-Johnston
Outdoor Control Circuit Failure
Indoor blower runs but outdoor unit does not (no fan, no compressor)
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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
Open low-voltage control wiring between air handler and condenser, Tripped low-pressure or high-pressure switch, Faulty condenser control board, Broken thermostat Y circuit
How to Fix / Troubleshooting
Safety: Turn off power to both indoor and outdoor units before handling wiring.
- Check thermostat wiring: At the air handler control board, verify 24 VAC between R and C, and between Y and C when cooling is called.
- Inspect low-voltage cable: At the condenser, verify 24 VAC is present at the contactor coil when cooling is called. If not, trace the low-voltage cable for breaks or splices.
- Pressure switches: Some Fraser‑Johnston units have manual reset high-pressure switches. Check for a small red reset button near the refrigerant lines and press if tripped (only after resolving airflow issues).
- Control board: If 24 VAC is present at the board but not being sent to the contactor, the outdoor control board may be faulty.
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Repair Difficulty
Medium
3/5
Required Part
Low-Voltage Control Wiring
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