Low pressure R134a vapor entering the
compressor is compressed to become high
pressure/temperature R134a vapor. This is
then circulated along with lubricant oil to the
condenser. As the high pressure/temperature
vapor travels through the condenser, heat is
released to the cooler ambient air passing
over the condenser tubes condensing the
vapor into a liquid. This high
pressure/temperature liquid then travels
through the filter drier onto the expansion
valve where a small variable orifice provides a
restriction against which compressor pushes.
Low pressure side
Suction from the compressor pulls the high
pressure/temperature liquid R134a through
small variable orifice of the TX valve and into
the low-pressure side of the A/C system.
The R134a is now under low
pressure/temperature vapor where heat from
the cabin being blown over the evaporator
coil surface is absorbed into the colder low
pressure refrigerant The R134a is then pulled
through the evaporator and into the
compressor. The A/C cycle begins again as
the R134a vapor is compressed and
discharged under pressure.
Heat transfer
R134a in the LOW-PRESSURE side is COLD
and can absorb large quantities of heat from
the air moving over the evaporator.
R134a in HIGH-PRESSURE side is HOT and
the cooler ambient air moving over the
condenser can absorb the heat from it.
Summary
- When the R134a pressure is low, the R134a
temperature is low.
- When the R134a pressure is high, the
R134a temperature is high.
Theory