Tadano TR-800XXL4, Service Manual

Page: 192 / 402

K - 2 K - 2
Air Conditioner
9 W701-0220E
2. Large variations in compressor speed
The compressor of a household air conditioner is
maintained at a constant motor speed. The
compressor in a car air conditioner is driven by
the engine, and its speed varies largely.
This means:
The amount of refrigerant circulating in the cycle
varies greatly.
3. For these reasons, the expansion valve is not a
simple throttle valve, but automatically adjusts the
flow in response to changes in the compressor
speed and cooling load, in order to always
maintain the optimal amount of refrigerant in the
cycle.
For this purpose, a receiver is installed to
temporarily store excess refrigerant.
4. In an actual air conditioning system, various
controllers to adjust temperature and airflow are
included to keep the inside of the cab comfortable.
3.6 Receiver functions
1. The receiver is installed between the condenser
and the expansion valve. It temporarily stores the
refrigerant after it has been liquefied by the
condenser, so that the refrigerant can be supplied
as needed to the evaporator according to the
cooling load.
2. Inside the receiver is a strainer and a desiccant,
which remove dust and moisture from the cooling
cycle.
If moisture enters the cycle, it will cause corrosion
of functioning parts, and will freeze in the hole of
the expansion valve, inhibiting the flow of
refrigerant.
3. There are two types of receivers – block joint type
and union type. The difference is the means of
connecting the pipes.
Sight glass
Dryer
Desiccant
Strainer
Strainer
Tube
Desiccant
OUT
IN
OUT
Block joint type Union type
IN
IW701-0110E08
In addition to temporarily storing the refrigerant,
the receiver also functions to separate gas and
liquid refrigerant.
4. Depending on the outside air conditions, not all of
the refrigerant may be liquefied when it is cooled
by the condenser.
If refrigerant gas is sent to the expansion valve, it
will degrade the cooling capacity.
5. Inside the receiver, liquid refrigerant is stored in
the lower part, while gas refrigerant is stored in
the upper part. Because the receiver exit pipe
takes only liquid refrigerant from the bottom, the
gas and liquid are kept separated.
Gas refrigerant
Liquid refrigerant
IW701-0110E09