High pressure gas
High pressure liquid
Low pressure liquid
Low pressure gas
Evaporator
Drier
Compressor
Expan-
sion
valve
Condenser
1138
Model
Code
Page
83. Air conditioner
1. 1. 1994
6000--8750
830
4
15. 6. 1992
Circulation of the refrigerant begins from the compressor. The
compressor sucks low pressure gas from the evaporator and
compresses high pressure gas into the condenser. In the con-
denser gaseous refrigerant becomes condensed and emits
heat to outdoors. From the condenser high pressure liquid
flows via a drier to the expansion valve in which a part of the
liquid vaporizes and the refrigerant cools and its pressure
drops. Liquid flows from the expansion valve into the evapor-
ator where cab heat changes liquid into gas. This low pres-
sure gas then flows into the compressor suction side from
where a new circulation begins.
Max. cooling effect corresponds to the situation when the
compressor works all the time. In order to achieve a certain
cooling effect, the compressor has to keep a certain pressure
in the evaporator outlet side.
An evaporation temperature of Freon R12 is ---30
˚
C at normal
air pressure. The corresponding value of the R134 is ---26
˚
C.
When pressure increases the evaporation temperature rises
and vice versa.
When the air conditioner is operating the low pressure hoses
are cold and high pressure hoses are warm.
Liquid refrigerant from the condenser is filtered and dried in
the drier container. The drier also prevents gaseous freon
from entering into the expansion valve. In the drier container
there is a pressure switch which switches off current to the
compressor if pressure in the high pressure circuit rises too
high or becomes too low:
In addition, the drier has a heat fuse (not if refrigerant R134a)
which melts at
107---118
˚
C
(corresponds pressure 3,4---3,8
MPa) and refrigerant blows off. The drier has two inspection
glasses through which can be checked the refrigerant filling
and moisture in the system (see page
831/2
).
