Tadano TR-800XXL4, Service Manual

Page: 189 / 402

K - 2 K - 2
Air Conditioner
6 W701-0220E
3.2 Conditions for air conditioning equipment
The conditions required for a high-performance air conditioner are the following.
Refrigerant vaporizes at the lowest temperature possible.
Refrigerant liquefies easily.
The largest possible quantity of refrigerant vaporizes in the evaporator.
1. When we look at the conditions of the refrigerant
within the refrigeration cycle, we find that the
refrigerant which was compressed by the
compressor becomes a high-temperature
high-pressure gas.
2. The refrigerant next enters the condenser, where
it is cooled and changed from gas to liquid form as
it passes through. All of the refrigerant must be
changed to liquid form when it reaches the
condenser outlet. If the condenser cooling is
insufficient, some refrigerant remains in gas form,
and will result in degraded cooling performance.
3. When the liquid refrigerant passes through the
expansion valve, it is atomized.
The expansion valve is also known as a throttle
valve. It sprays the high-pressure liquid through a
small nozzle to create a refrigerant mist. This
allows the refrigerant to vaporize easily.
4. In the evaporator, the refrigerant mist absorbs
heat from the cab and vaporizes rapidly. By the
time it reaches the evaporator outlet, the
refrigerant has been completely transformed to a
vapor.
5. If the amount of refrigerant is insufficient, it
completely evaporates in the middle as it passes
through the evaporator. This results in degraded
performance of the evaporator.
6. On the other hand, if there is too much refrigerant,
it cannot vaporize in the evaporator, and some
remains in liquid form when it enters the
compressor. If this occurs, there is the possibility
that compressing liquid instead of vapor will
damage the compressor.
7. For these reasons, the amount of refrigerant must
be adjusted according to meet a variety of
conditions.
8. The purpose of the air conditioner is to provide a
comfortable environment not only by lowering the
cab temperature, but also by reducing the
humidity. This is accomplished by cooling the hot
air in the cab, and condensing the moisture in it
when it passes the evaporator.
9. In this way, the moisture in the air is removed,
reducing the humidity. The water droplets that
adhere to the fins are led to the outside of the
vehicle through a hose.