Freezer not cooling at all; interior light works but temperature remains warm and food is thawing.

Safety first: Unplug the freezer before removing rear panels. Do not attempt sealed-system repairs unless qualified.

Steps to diagnose no cooling:

• 1. Listen for compressor: After plugging in (for testing), listen at the back. A healthy compressor will hum steadily. Repeated clicking or silence suggests a start or control issue.
• 2. Check condenser fan (if fitted): On some Proline uprights, a fan near the compressor should run when cooling. If not, there may be a control or power issue.
• 3. Inspect start relay/PTC: Unplug the unit, remove the rear lower panel, and locate the start device on the compressor. Remove it and check for burn marks or rattling pieces. Replace with a compatible Proline start relay/PTC if damaged.
• 4. Test compressor windings: With the start device removed and power off, measure resistance between compressor terminals. Open or shorted windings indicate a failed compressor.
• 5. Control board check: If the compressor and start device appear good but never receive power, the main control PCB or thermostat may be faulty and require replacement.

When to call a technician: If the compressor windings are faulty or the system has lost refrigerant, a professional sealed-system repair is required.