6--5
T-334
6.4 REFRIGERATION SYSTEM SERVICE - UNITS
WITH SEMI-HERMETIC PIPING (without Ser-
vice Valves)
6.4.1 Service Connections
The compressor is fitted with access valves at the
suction connection, economizer fitting and liquid line
fitting to enable servicing of the system. Refrigerant
must be removed from system before performing
service.
To connect the manifold gauge/hose set for reading
pressures, do the following:
1. Remove access valve cap. (See Figure 2-3.)
2. Connect the field service coupling to the access
valve.
3. Turn the field service coupling knob clockwise, which
will open the system to the gauge set.
4. Repeat the procedure to connect the other side of
the gauge set.
CAUTION
To prevent trapping liquid refrigerant in the
manifold gauge set be sure set is brought to
suction pressure before disconnecting.
1. While the compressor is still ON, backseat the high
side service valve.
2. Midseat both hand valves on the manifold gauge set
and allow the pressure in the manifold gauge set to
be drawn down to low side pressure. This returns
any liquid that may be in the high side hose to the
system.
3. Backseat the low side service valve. Backseat both
field service couplings and frontseat both manifold
hand valves. Remove the field service couplings
from the access valves.
4. Install both service valve stem caps and service port
caps (finger-tight only).
6.4.2 Refrigerant Recovery
To remove the refrigerant for service, do the following:
a. Connect the three access valves to the refrigerant
recovery unit as shown in Figure 6--5. Following the
refrigerant recovery unit manufacturers instructions,
start the recovery process.
b. To ensure complete removal of refrigerant, check that
the suction modulating valve is more than 10% open
at controller function code Cd01. If required, the suc-
tion modulating valve may be opened by use of con-
troller function code Cd41 valve override control.
c. Break the vacuum and bring the system to a slight
positive pressure using dry nitrogen. When refriger-
ant is fully recovered, remove the refrigerant recovery
unit.
d. Perform repairs as required and then leak test, evac-
uate, charge and reseal unit in accordance with the
following paragraphs.
D
S
10
8
9
6
7
1
2
3
4
5
11
1. Liquid Access Valve
2. Receiver or Water
Cooled Condenser
3. Compressor
4. Discharge Service
Connection
5. Economizer Access
Valve
6. Suction Access Valve
7. Vacuum Pump
8. Electronic Vacuum
Gauge
9. Manifold Gauge Set
10. Refrigerant Cylinder
11. Reclaimer
Figure 6--5 Semi-Hermetic Piping Refrigeration
System Service Connections
6.4.3 Refrigerant Leak Checking
DANGER
Never use air for leak testing. It has been
determined that pressurized, air-rich mix-
tures of refrigerants and air can undergo
combustion when exposed to an ignition
source.
The recommended procedure for finding leaks in a
system is with a R-134a electronic leak detector. Testing
joints with soapsuds is satisfactory only for locating
large leaks.
NOTE
Only refrigerant 134a should be used to pres-
surize the system. Any other gas or vapor will
contaminate the system, which will require
additional purging and evacuation of the sys-
tem.
If the system is without refrigerant, charge with
refrigerant 134a to build up pressure between 2.1 to
3.5 kg/cm
2
(30 to 50 psig).
To ensure complete pressurization of the system,
refrigerant should be charged at all of the access valves.
DO NOT charge liquid at the suction or economizer
fittings, charge only vapor.
Liquid may be charged at the liquid line. To ensure
pressure to this area, check that the suction modulating
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