PREVOST X3-45 Multiplex, Maintenance Manual

Page: 1176 / 1422

Section 22: HEATING AND AIR CONDITIONING
PA1562
34
VAPOR-PRESSURE
TEMPERATURE PRESSURE
°F °C psi kPa
190 87.8 433.6 2989.7
200 93.3 485.0 3344.1
210 98.9 540.3 3725.4
7.12 LEAK TESTING
Some methods such as nitrogen pressure, soap
and electronic sniffer can be used for leak
testing. However, the most common method
used is a "Halide" torch consisting of an
acetylene tank, a burner and a suction test
hose. Proceed as follows:
DANGER
Do not inhale fumes from leak detector.
The flow of acetylene to the burner causes
suction in the test line. Any gas refrigerant
present will be drawn through the hose and into
the burner where it decomposes into free acids.
These acids come in contact with the hot copper
reaction plate in the burner, causing color
reaction in the flame. A small concentration is
indicated by a green tint and a large
concentration by an intense blue. Do not
confuse this change in color with the change
caused by shutting off the air supply through the
hose by holding the end too close to an object.
The procedure for testing is:
1. Adjust flame so that the top of the cone is
approximately level or within one-half inch
above the plate.
2. Probe end of suction test tube around all
joints, valves, etc. When a leak has been
found at a soldered joint, this section of the
system must be pumped down. Do not
solder as pressure will force hot solder out.
If the system is empty, it is more
economical to put in just enough R-134a to
produce about 15 psi (103 kPa). The
pressure can be raised to about 150 psi
(1034 kPa) with dry nitrogen.
NOTE
This gas is put into the suction and discharge
shutoff valves at the compressor. The receiver
valves must be opened. If no leaks are found,
dump this mixture, evacuate the system and
fill with refrigerant.
8. AUXILIARY AIR CONDITIONING SYSTEM
AND COMPONENTS
8.1 COMPRESSOR
Consult the small Compressor Service Manual
included at the end of this section.
WARNING
Read the cautionary information in the small
Compressor Service Manual included at the
end of this section.
8.2 COMPRESSOR REMOVAL
8.2.1 When the compressor is operational
*
Perform the “OIL RETURN OPERATION”
(Refer to paragraph 8.5).
8.2.2 When the compressor is inoperable
*
Perform the “Refrigerant Recovery”
operation.
* Slacken bolts A (Refer to figure 35).
* Remove bolts B & C (Refer to figure 35).
* Remove the compressor.