Service manual

6-- 1
T--318
SECTION 6
SERVICE
NOTE
To avoid damage to the earth’s ozone layer, use a refrigerant recovery system whenever removing
refrigerant. When working with refrigerants, you must comply with all local government environmental laws. In
the U.S., refer to EPA section 608.
WARNING
Never use air for leak testing. It has been
determined that pressurized mixtures of
refrigerant and air can undergo combustion
when exposed to an ignition source.
6.1 SECTION LAYOUT
Service procedures are provided herein beginning with
refrigeration system service, then refrigeration system
component service, electrical system service,
temperature recorder service, and general service.
Refer to the Table Of Contents to locate specific topics.
6.2 SERVICE VALVES
The compressor suction, compressor discharge, and
liquid line service valves (see Figure 6-1) are provided
with a double seat and a gauge connection, which
enable servicing of the compressor and refrigerant
lines. Turning the valve stem clockwise (all the way
forward) will frontseat the valve to close off the suction,
discharge or liquid line and open the gauge port to the
compressor or low side. Turning the stem
counterclockwise (all the way out) will backseat the
valve to open the connections and close off the port
With the valve stem midway between frontseat and
backseat, the lines are open to both the connections and
the gauge connection.
For example, the valve stem is first fully backseated
when connecting a manifold gauge to measure
pressure. Then, the valve is opened 1/4 to 1/2 turn to
measure the pressure.
VALVE
FRONTSEATED
(Clockwise)
VALVE
BACKSEATED
(Counterclockwise)
5
1
23
4
1. Suction, Discharge or
Liquid Line
Connection
2. Service Port
3. Stem Cap
4. Valve stem
5. Compressor Or Filter
Drier Inlet Connection
Figure 6-1 Service Valve
OPENED (Backseated )
HAND VALVE
CLOSED (Frontseated)
HAND VALVE
SUCTION
PRESSURE
GAUGE
DISCHARGE
PRESSURE
GAUGE
A
BC
A. Connection to Low Side of System
B. Connection to either :
Refrigerant Cylinder or
Oil Container
C. Connection to High Side of System
Figure 6-2 Manifold Gauge Set
6.3 MANIFOLD GAUGE SET
The manifold gauge set (see Figure 6-2) is used to
determine system operating pressure, add refrigerant
charge, and to equalize or evacuate the system.
When the suction pressure hand valve is frontseated
(turned all the way in), the suction (low) pressure can be
checked. When the discharge pressure hand valve is
frontseated, the discharge (high) pressure can be
checked. When both valves are open (turned
counter-clockwise all the way out), high pressure vapor
will flow into the low side. When the suction pressure
valve is open and the discharge pressure valve shut, the
system can be charged. Oil can also be added to the
system.
A R-134a manifold gauge/hose set with self-sealing
hoses (see Figure 6-3) is required for service of the
models covered within this manual. The manifold
gauge/hose set is available from Carrier T ransicold.
(Carrier T ransicold P/N 07-00294-00, which includes
items 1 through 6, Figure 6-3). To perform service using
the manifold gauge/hose set, do the following:
a. Preparing Manifold Gauge/Hose Set For Use
If the manifold gauge/hose set is new or was exposed to
the atmosphere, it will need to be evacuated to remove
contaminants and air as follows:
1. Back seat (turn counterclockwise) both field service
couplings (see Figure 6-3) and midseat both hand
valves.
2. Connect the yellow hose to a vacuum pump and
refrigerant 134a cylinder .
3. Evacuate to 10 inches of vacuum and then charge
with R-134a to a slightly positive pressure of 0.1
kg/cm@ (1.0 psig).