Figure 6-1. Piercing Valve; Service - Carrier 69NT40--541--200 TO 299 Operation And Service

NOTE
To avoid damage to the earth's ozone layer, use
a refrigerant recovery system whenever remov-
ing refrigerant. When working with refrigerants
you must comply with all local government envi-
ronmental laws. In the U.S.A., refer to EPA sec-
tion 608.
6.1 REPAIRING THE REFRIGERATION SYSTEM
The unit is designed as a hermetic system, which
reduces the number of potential leak-points for
refrigerant. Therefore the suction service, discharge
service and manual liquid line valves have been
eliminated in comparison to the standard container unit.
In conjunction, the sight glass on the water-cooled
condenser, and the filter-drier quick--connect nuts have
also been removed. These areas have either been
completely eliminated, or have been replaced with
brazed joints.
To perform maintenance on the system, two process
tubes have been provided, which are the liquid line and
suction line process tubes . Refer to Table 6-7 for a list
of the tools required to perform the tasks.
6.2 PIERCING VALVES
To gain access to the hermetic system, it is
recommended to use the Robinair P/N 40288 piercing
valve on the units process tubes.
a. Preparation
1. Tubing should be straight and round.
2. Carefully clean the process tubing where the
piercing valve will be attached, do NOT scratch the
tubing.
3. Make sure there are no dents in the tubing.
4. Apply a little clean refrigerant oil to the tubing where
the piercing valve will be placed.
b. Installing
1. Make sure the gasket (item 2, refer to Figure 6-1) is
in place, and the piercing needle (item 3) is backed
all the way out by turning the hand valve (item 1)
counter-clockwise.
2. Remove the nut (item 5) and u-shaped block (item
4) from the base of the piercing valve.
3. Straddle the process tube with the hand valve
portion of the piercing valve.
SECTION 6

SERVICE

4. Install the u-shaped block and nut onto the base of
the piercing valve that was removed in step 2.
5. Tighten the valve to the process tube by turning the
nut enough to seal the gasket and to secure the
valve to the process tube.
6. Do NOT overtighten. Overtightened valves can
actually cause a leak.
7. Install the manifold gauge hose (refer to section 6.3)
to the one-quarter inch connector using a low or
high side R-134a connector or a low or high side
swivel elbow.
8. Turn the hand valve clockwise to pierce the tubing
and access the refrigeration system.
6
1.Hand Valve
3.Piercing Needle
5.Nut

Figure 6-1. Piercing Valve

c. Removal
1. Reverse the steps in section 6.2.b.
6.3 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 6-2 shows hand valves, gauges and service
ports "A, C and B." When the low pressure hand valve is
frontseated (turned all the way in), the low (suction)
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.
6-1
1
2
3
4
5
2. Gasket
4. U-Shaped Block
6.1/4" S.A.E. Connector
T--317