The refrigeration cycle moves heat, not “cold.” The refrigerant absorbs heat in the EVAPORATOR (low pressure/low temp), is pressurized by the COMPRESSOR (raises pressure and temperature), rejects heat in the CONDENSER (high pressure/high temp), then is pressure-dropped by the METERING DEVICE (TXV/cap tube) to feed the evaporator again.   Key keywords to remember: • Evaporator = heat absorbed, refrigerant boils, low-side • Compressor = “pump,” raises pressure/temperature, creates pressure differential • Condenser = heat rejected, refrigerant condenses to liquid, high-side • Metering... Show more

The refrigeration cycle moves heat, not “cold.” The refrigerant absorbs heat in the EVAPORATOR (low pressure/low temp), is pressurized by the COMPRESSOR (raises pressure and temperature), rejects heat in the CONDENSER (high pressure/high temp), then is pressure-dropped by the METERING DEVICE (TXV/cap tube) to feed the evaporator again.
 

Key keywords to remember:
• Evaporator = heat absorbed, refrigerant boils, low-side
• Compressor = “pump,” raises pressure/temperature, creates pressure differential
• Condenser = heat rejected, refrigerant condenses to liquid, high-side
• Metering device = pressure drop + flow control, creates low-side
Typical states (conceptual):
• Leaving evaporator: low-pressure vapor (often slightly superheated)
• Leaving compressor: high-pressure superheated vapor
• Leaving condenser: high-pressure liquid (often subcooled)
• Leaving metering device: low-pressure liquid/vapor mix (“flash gas”)

Worked example (concept):
If the condenser is dirty, heat rejection falls → head pressure rises → compressor amps rise → capacity drops. (Common exam linkage: dirty condenser → high head pressure.)

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