Vehicles after change point in 1982
FUNCTION OF REFRIGERANT CIRCUIT
After switching on the air conditioner the refrigerant circuit goes into action, i.e.
the magnetic coupling coil receives power to produce a magnetic field which pulls the
armature clutch plate, which is fixed on the compressor shaft next to the internal disc
turning freely on the same shaft. Friction is consequently employed to drive the
compressor.
The compressor, a major component of the system, increase the pressure of the
refrigerant vapors. Refrigerant vapors are taken in on the suction side of the
compressor. The refrigerant is compressed by three double-action pistons arranged
axial to the drive shaft, whereby the vapor temperature rises. These high pressure
vapors travel via a high pressure line to the condenser located on the front of the
engine radiator. The high pressurized, hot refrigerant is cooled by wind and an extra
fan. When reaching a certain temperature the vapors condense, become liquid and
are cooler. The high pressurized refrigerant travels to the fluid tank/drier. The drier
removes moisture and also acids from the refrigerant, this however only to the amount
of approx. 6 to 10 grams.
The refrigerant continues from the drier to the expansion valve, which is a separating
point in the system. The expansion valve meters the refrigerant volume. The injection
rate will be controlled by the temperature and pressure at the outlet of the evaporator.
In the evaporator the refrigerant evaporates and cools off considerably. The stream
of fresh air, supported by a blower, moving past a cold evaporator will be cooled
accordingly and forwarded through nozzles into the passenger compartment. The
evaporated refrigerant will again be taken in by the compressor, so that the
refrigerant circuit is closed.
Moisture in the fresh air or ambient air, which streams around the evaporator, condenses
on the cool plates. The condensation on the evaporator is discharged via two rubber
hoses on the transmission tunnel and could cause a puddle of up to two liters
underneath a parked car depending on the moisture in the air. This is completely
normal and not indication of a defect in the systems.
It could happen that the condensation freezes on the plates of the evaporator. A
temperature switch with a capillary sensor protects the evaporator against ice and
switches the air conditioner off when ice starts to form. This stops the refrigerant
circuit and the evaporator ice can melt. The temperature switch will then release the
power flow again, the magnetic coupling engages and the refrigerant circuits work
again.
Pre-requisites for a perfect working air conditioning system are maximum cleanliness
for all jobs on the air conditioner and as perfect as possible discharging (removal of
moisture in the refrigerant circuit) of the air conditioner.

 
1 = Electromagnetic coupling
2 = Compressor
3 = Condenser
4 = Drier
5 = Safety switch (low pressure pressostat)
6 = Safety switch (high pressure pressostat)
7 = Expansion valve
8 = Evaporator
9 = Temperature switch
10 = High pressure gas
11 = High pressure liquid
12 = Low pressure liquid
13 = Low pressure gas

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