Applicable Systems
Copeland Scroll Compressor (CoreSense/Comfort Alert)
Symptoms
The compressor reports a contactor fault. The main contactor has failed to pull in or has welded contacts, preventing proper compressor control.
Possible Causes
- Contactor coil burned out or open circuited
- Contactor contacts welded shut from arcing
- Control circuit voltage low preventing contactor pickup
Troubleshooting Steps
- Step 1: Test the contactor coil for continuity and proper resistance
Coil resistance matches the rated value - Step 2: Inspect contacts for pitting, welding, or excessive wear
Contacts are clean and make positive contact - Step 3: Verify control circuit voltage at the contactor coil
Voltage is within 10 percent of rated coil voltage
How to Reset
To reset: Replace the faulty contactor or restore control voltage, then reset the safety circuit.
Source: Copeland Scroll Compressor Service Manual, Emerson Climate Technologies
Category: Refrigeration