Refrigeration & Air Conditioning Mechanic Red Seal · Question
A refrigeration technician is called to troubleshoot a walk-in freezer operating with a discharge temperature that is consistently 20°C (36°F) higher than normal, accompanied by intermittent high-pressure cut-out trips. The system uses R404A. What is the most probable cause?
Non-condensable gases (like air or nitrogen) in the system elevate the condensing pressure and discharge temperature without contributing to refrigeration, lead
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Question: A refrigeration technician is called to troubleshoot a walk-in freezer operating with a discharge temperature that is consistently 20°C (36°F) higher than normal, accompanied by intermittent high-pressure cut-out trips. The system uses R404A. What is the most probable cause?
Answer options:
- Insufficient refrigerant charge.
- Expansion valve stuck open.
- Dirty evaporator coil. ✅ Non-condensable gases in the system.
Correct answer: Non-condensable gases in the system.
Explanation: Non-condensable gases (like air or nitrogen) in the system elevate the condensing pressure and discharge temperature without contributing to refrigeration, leading to high-pressure cut-outs and higher-than-normal discharge temperatures.
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Question explanations
- Which of the following refrigerants is a hydrofluorocarbon (HFC) and has a high ozone depletion potential (ODP
- Which component is responsible for compressing the refrigerant vapour to a high pressure and temperature?
- According to the Canadian Electrical Code (CEC), what is the minimum required working clearance in front of el
- What is the main operating characteristic difference between a fixed orifice (capillary tube) and a Thermostat
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