Carrier 69NT40-511-199 - Manual (Page 95)

SECT
IO
N
6
6-1 T-268-07
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.A., refer to EPA section 608.
6.1 MANIFOLD GAUGE SET
The manifold gauge set can be used to determine system
operating pressure, add a refrigerant charge, and to
equalize or evacuate the system.
Figure 6-1 shows hand valves, gauges and refrigerant
openings. When the low pressure hand valve is
frontseated (turned all the way in), the low (evaporator)
pressure can be checked. When the high pressure hand
valve is frontseated, high (condensing) 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 low pressure valve
is open, the system can be charged. Oil can also be
added to the system.
Only a R-134a manifold gauge set with self-sealing
hoses, as shown in Figure 6-2 (CTD P/N 07-00294-00,
which includes items 1 through 6) can be used when
working on the models covered within this manual.
Opened
(Backseated Hand Valve )
Closed
(Frontseated Hand Valve)
Low Pressure Gauge High Pressure Gauge
A B C
A. Connection to Low Side of System
B. Connection to High Side of System
C. Connection to Either:
Refrigerant Cylinder or
Oil Container
Figure 6-1. Manifold Gauge Set
a. Connecting the Manifold Gauge Set
(See Figure 6-2)
1. Remove service valve stem caps and check both
service valves to make sure they are backseated
(turned counter-clockwise all the way out). Remove
service port caps.
2. Connect the high side field service coupling
(backseated) to the discharge service valve port (or
the manual liquid line valve port, whichever is
applicable).
3. Turn the high side field service coupling (red knob)
clockwise, which will open the high side of the
system to the gauge set.
4. Connect the low side field service coupling to the
suction service valve port.
5. Turn the low side field service coupling (blue knob)
clockwise, which will open the low side of the
system to the gauge set.
6. To read system pressures: slightly midseat the
discharge and suction service valves, and frontseat
both manifold gauge set hand valves.
NOTE
If a manifold gauge set is new or was exposed to
the atmosphere due to repair, it will need to be
evacuated to remove contaminants and air as
follows:
S Midseat both hand valves.
S
Connect the utility hose (yellow) to a vacuum
pump.
S Evacuate to 10 inches of vacuum.
S Charge with R-134a to a slightly positive
pressure of 0.1 kg/cm@ (1.0 psig). The gauge
set is now ready for use.