Carrier 69NT40-541-001, Operation And Service

Page: 90 / 156

T-316 7–2
Figure 7.2 Manifold Gauge Set
7.3 MANIFOLD GAUGE SET
The manifold gauge set (see Figure 7.2 ) 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 counterclockwise 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 7.3 ) 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 7.3 .) To perform service using the manifold gage/hose
set, do the following:
a. Preparing Manifold Gauge/Hose Set For Use
1. 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:
2. Back seat (turn counterclockwise) both field service couplings (see Figure 7.3 ) and midseat both hand
valves.
3. Connect the yellow hose to a vacuum pump and refrigerant 134a cylinder.
4. Evacuate to 10 inches of vacuum and then charge with R-134a to a slightly positive pressure of 0.1 kg/
cm² (1.0 psig).
5. Front seat both manifold gauge set valves and disconnect from cylinder. The gauge set is now ready for use.
OPENED (Backseated )
HAND VALVE
CLOSED (Frontseated)
HAND VALVE
SUCTION
PRESSURE
GAUGE
DISCHARGE
PRESSURE
GAUGE
A
B C
A. CONNECTION TO LOW SIDE OF SYSTEM
B. CONNECTION TO EITHER:
REFRIGERANT CYLINDER OR
OIL CONTAINER
C. CONNECTION TO HIGH SIDE OF SYSTEM