Carrier 69NT40-541-300, Operation And Service, Page: 89 / 152

6 − 1 T − 318
SECTION 6
SERVICE
NOTE
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
EXPLOSION HAZARD: Failure to follow this
WARNING can result in death, serious
personal injury and / or property damage.
Never use air or gas mixtures containing
oxygen (O
2
) for leak testing or operating the
product.
Charge Only With R
− 134a: Refrigerant must
conform to AHRI Standard 700
specification.
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 MANIFOLD GAUGE SET
The manifold gauge set (see Figure 6-1) is used to
determine system operating pressure, add refrigerant
charge, and to equalize or evacuate the system.
1
2
3
4
5
6 7
1. Suction Pressure Valve (shown backseated)
2. Suction Pressure Gauge
3. Discharge Pressure Gauge
4. Discharge Pressure Valve (shown frontseated)
5. High Side Connection
6. Utility Connection to either:
a. Refrigerant cylinder
b. Vacuum Pump
c. Oil Container
7. Low Side Connection
Figure 6-1 Manifold Gauge Set
When the Suction Pressure Valve (1) is frontseated
(turned all the way in), the suction (low) pressure can be
checked at the Suction Pressure Gauge (2).
When the Discharge Pressure Valve (4) is frontseated,
the discharge (high) pressure can be checked at the
Discharge Pressure Gauge (3).
When both valves are backseated (all the way out), high
pressure vapor will flow into the low side.
When the Suction Pressure Valve (1) is open and the
Discharge Pressure Valve (4) is shut, the system can be
charged through the Utility Connection (6). Oil can also
be added to the system.
A R-134a manifold gauge/hose set with self-sealing
hoses (see Figure 6-2) is required for service of the
models covered within this manual. The manifold
gauge/hose set is available from Carrier Transicold.
(Carrier Transicold P/N 07-00294-00, which includes
items 1 through 6, Figure 6-2).
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. Backseat (turn counterclockwise) both field service
couplings (see Figure 6-2) and midseat both hand
valves.
2. Connect the yellow hose to a vacuum pump and re-
frigerant 134a cylinder.
ÂÂ
ÂÂ
Â
Â
Â
Â
To High Side
Access Valve
Â
4
1
4
5
7
3
To Low Side
Access Valve
2
2
6
1. RED Refrigeration and/or Evacuation Hose
(SAE J2196/R-134a)
2. Hose Fitting (0.5-16 Acme)
3. YELLOW Refrigeration and/or Evacuation Hose
(SAE J2196/R-134a)
4. Hose Fitting with O-ring (M14 x 1.5)
5. High Side Field Service Coupling (Red Knob)
6. BLUE Refrigeration and/or Evacuation Hose
(SAE J2196/R-134a)
7. Low Side Field Service Coupling (Blue Knob)
Figure 6-2 R-134a Manifold Gauge/Hose Set
3. Evacuate to 10 inches of vacuum and then charge
with R-134a to a slightly positive pressure of
0.1kg/cm (1.0psig).
4. Frontseat both manifold gauge set valves and dis-
connect from cylinder. The gauge set is now ready
for use.