Top Roof Mounted Refrigerant System Troubleshooting
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Compressor Does Not Start After Power Is Connected
Possible Causes
1. Loose electrical wiring or terminal connections.
2. Low supply voltage or undersized power cable.
3. Contactor is not engaging.
Troubleshooting Steps
1. Check the power supply
● Ensure the power cable is at least 13 AWG (or larger) and not excessively long.
● Verify the supply voltage is above 200V.
2. Check the contactor
● When the unit is powered on for the first time, wait approximately 3 seconds.
● Observe whether the contactor pulls in.
● If it does not engage, carefully use an insulated screwdriver to manually press the
contactor.
● If the compressor starts after manual activation, the contactor or its control circuit may be
faulty.
3. Inspect the wiring
● Refer to the wiring diagram before troubleshooting.
● Check all wiring terminals for loose connections.
● Press on the compressor terminal cover to ensure it is fully seated.
● Open the compressor start box and verify that all capacitor wiring connections are
secure.
Note
This type of issue is uncommon under normal operating conditions. If the above checks do not
resolve the problem, further electrical diagnosis or component replacement may be required.