Refrigeration & Air Conditioning Mechanic Red Seal · Question
A contractor notices a residential air conditioning unit running R-410A has an unusually high discharge temperature and low suction pressure. The system is consuming more power than normal. Which of the following is the most likely cause?
An undercharge of refrigerant reduces the mass flow rate through the evaporator, leading to low suction pressure, increased superheat, and thus higher discharge
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Question: A contractor notices a residential air conditioning unit running R-410A has an unusually high discharge temperature and low suction pressure. The system is consuming more power than normal. Which of the following is the most likely cause?
Answer options:
- Overcharge of refrigerant.
- Condenser fan motor failure. ✅ Undercharge of refrigerant.
- Dirty evaporator coil.
Correct answer: Undercharge of refrigerant.
Explanation: An undercharge of refrigerant reduces the mass flow rate through the evaporator, leading to low suction pressure, increased superheat, and thus higher discharge temperatures at the compressor as it works harder.
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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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