Proline freezer displays E9 and may not cool; compressor does not run even though lights and display are on.

Safety first: Disconnect the freezer from mains before accessing the control board.

Steps to address E9:

• 1. Power reset: Unplug the unit for 10–15 minutes, then reconnect. If E9 returns immediately, proceed with inspection.
• 2. Access main control PCB: On many Proline freezers, the main board is located in a rear control box or behind the top control fascia. Remove the cover carefully.
• 3. Visual inspection: Look for burned components, swollen capacitors, or cracked solder joints, especially around the compressor relay.
• 4. Check connectors: Ensure all harnesses are fully seated and not heat-damaged.
• 5. Basic relay test (advanced): With power applied and a cooling demand present, listen/feel for the compressor relay clicking. If there is no click and the board shows visible damage, replacement is likely required.
• 6. Replace main control PCB: Order the correct Proline main control board by model number. Transfer any jumper settings or wiring exactly as original. Label connectors before removal to avoid miswiring.

Note: Board-level repair is not recommended for most users. If you are not experienced with electronics, have a technician replace the PCB.