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Checking the Refrigerant
Pressure
When using the air-conditioning system the operating
pressure is different on the suction side and the pressure side
of the compressor.
This pressure difference is influenced by the speed of the
compressor, the inside temperature of the vehicle, the outside
air temperature and the relative air humidity.
System Refrigerant Pressures
Outside Temperature
20° C (68° F)
25° C (77° F)
30° C (86° F)
Troubleshooting the Pressure
Readings
During the compression test, deviations from the values in
the table may be measured. Locating the cause can determine
whether a part requires repair or replacement.
The following is a short list of some pressure deviation that
may be measured and some possible causes.
•
Pressure on high-pressure manometer too high
– The air volume in the condenser is too small.
– Refrigerant quantity is too high
– The dryer/filter is blocked.
•
Pressure on high-pressure manometer is too low
– The refrigerant quantity is too low (check the sight
glass).
– The compressor speed is too low (check the drive
belt for slip/tension).
– There is a fault with the compressor.
•
Pressure on low-pressure manometer too high
– The expansion valve is incorrect.
– The compressor speed is too low (check the drive
belt for slip/tension).
– There is a fault with the compressor.
•
Pressure on low-pressure manometer too low
– There is restriction in the suction or pressure hoses.
– The expansion valve is incorrect.
– The refrigerant quantity is too low (examine the
sediment bowl).
– The air volume in the evaporator is too small.
Have a qualified person examine and repair all deviations
in pressure from the values in the table.
Important: Do not allow refrigerant to discharge into
the atmosphere. Before opening or disconnecting parts
Pressures that differ from those in the table below indicate a
possible fault in the system.
To check the pressures, set the compressor speed to 2000
rpm with an air temperature between 20 and 40 degrees C (68
and 104 degrees F). Operate the blower at position 3 (fastest
speed setting).
Low-Pressure Side
1.7 to 2.1 bar (24.7 to 30.5 psi)
1.8 to 2.2 bar (26.1 to 31.9 psi)
1.9 to 2.3 bar (27.6 to 33.4 psi)
from the refrigerant circuit, empty the refrigerant into a
specified recycling bottle, and dispose of it correctly.
Always use genuine Toro spare parts when repairing or
servicing the air-conditioning system.
Checking the Refrigerant Level
Service Interval: Every 50 hours
Check the refrigerant to assure it is at the correct level for
operation. As the level of the refrigerant lowers, more
air bubbles can be seen passing through the sight glass.
Low levels of refrigerant can reduce the efficiency of the
air-conditioning unit. Extremely low levels can cause the
low-pressure switch to shut down the system.
1. Using the sight gauge in the collecting tank, check on
1. Refrigerant-level sight gauge
2. After filling, run the system for 5 minutes to allow all
8
High-Pressure Side
10 to 14 bar (145 to 203 psi)
12 to 16 bar (174 to 232 psi)
14 to 18 bar (203 to 261 psi)
refrigerant level
(Figure
6).
g019080
Figure 6
air bubbles to be purged from the system.
1
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