Temperature controls (thermostats) and other electronic controls can fail at any time in the life of a fridge-freezer for various reasons, including poor components and manufacture, and due to the thermal cycling and occasional vibration they may suffer inside the unit.
The specification below provides the recommended improvements needed to improve product durability. They are ranked from bronze to gold based on the effectiveness of the change in improving durability, with bronze being the minimum and gold being the maximum.
Thermostat type and connectors
PCB quality and inspection
Environmental test standards
* Environmental testing should be undertaken by an independent laboratory to:
Relevant test methods include EN 60068-2-6:2008 (environmental testing Part 2-6: Test Fc: Vibration (sinusoidal)) and EN 60068-2-64 (environmental testing Part 2-64: Test Fh: Vibration, broadband random) for vibration resistance for circuit boards. Connectors can be tested using the methods in EN 60512-6-4 Connectors for Electronic Equipment - Tests and Measurements - Part 6-4: Dynamic Stress Test 6d: Vibration (Sinusoidal).
The thermostat should be tested for 75,000 cycles (seven year lifetime). Test conditions should reflect IEC 60335-1:2013 and be carried out at ambient temperature.The heater and controls should last 2 500 cycles (~7 years), in line with the UL 250 (Canadian standards for Household Refrigerators and Freezers) Clause 8.20.1. Ask for clear evidence of meeting the requirements listed above, e.g.:
Improved reliability of components can reduce early returns and improve brand reputation which, in turn, can lower business costs and increase long-term sales.
To calculate overall cost savings for your business, use the WRAP cost/benefit analysis tool (currently in draft form and available on request).
These give more efficient and reliable control of temperatures in the fridge freezer.
Simple inspection procedures will help to identify manufacturing faults and component issues, reduce failure rates and customer returns.
Accessible / Replaceable Parts
Accessible and replaceable thermostat parts will reduce the cost and increase probability of replacement
Surface mount and conformal PCB coatings
Surface mount and conformal coatings will increase life and reliability of PCBs.
Gold plated connectors increase the reliability of PCBs.
PCB inspection and environmental testing
Additional testing and inspection of circuit boards will help to reduce failures and increase reliability and life of these components.