Purging Air From Service Hoses; Adding Refrigerant To The System; Purging System - Komatsu 930E-2 Shop Manual

Purging Air From Service Hoses

The purpose of this procedure is to remove all the air
trapped in the hoses prior to actual system testing.
Environmental regulations require that all service
hoses have a shutoff valve within 12 inches of the
service end. These valves are required to ensure only
a minimal amount of refrigerant is lost to the atmos-
phere. R-134a gauge sets have a combination quick
disconnect and shutoff valve on the high and low sides.
The center hose also requires a valve.
The initial purging is best accomplished when con-
nected to recovery or recycle equipment. With the
center hose connected to the recovery station, service
hoses connected to the high and low sides of the
system, we can begin the purging. The manifold valves
and service valves should be closed. Activating the
vacuum pump will now pull any air or moisture out of
the center hose. This will require only a few minutes of
time. The hose is the only area that is being placed in
a vacuum and this will not require a lengthy process.
Closing the valve will then insure the hose is purged. It
is now safe to open the other manifold valves.
M9-12

Adding Refrigerant to the System

(without a charging station)
After determining that the system is low and requires
additional refrigerant perform the following proce-
dures.
1. Connect the center hose from the manifold gauge
set to the refrigerant dispensing valve on the con-
tainer.
2. Start the engine and set the idle at 1200 to 1500
RPM and then turn on the air conditioning.
3. Open the refrigerant dispensing valve on the con-
tainer and then the low pressure hand valve on the
manifold. This will allow the refrigerant to enter the
system as a gas on the low pressure or suction
side of the compressor. The compressor will pull
refrigerant into the system.
4. Continue adding refrigerant until the gauge reads
in the normal range. Gauge readings will fluctuate
as the compressor cycles on and off.
Pressures within the air conditioning system vary
with ambient temperature. A normal pressure
range is defined as follows:
Low side 15 - 30 PSI
High side 170 - 300 PSI
FIGURE 9-9. PURGING SYSTEM
Air Conditioning System
for HFC 134a Refrigerant
M09010 6/97