remain open throughout sweep procedure), open valve A to allow three (3) ounces of refrigerant
into the system. Close valve A. Check low side for leaks. After system has equalized (about 3
to 5 minutes), start system compressor, check for high side leaks and allow refrigerant to
circulate in the system about 5 minutes.
Step 3.
Leave valve A closed and valve C open. System compressor still running, open valve B
to allow refrigerant to flow into the recovery system. After vacuum has been held, turn off system
compressor.
Step 4.
Close valve B. Liquid refrigerant still present to valve A and charging cylinder pressure
is 30 p.s.i.g. above room ambient. Open
valve A to slowly allow the proper
refrigerant charge into the system. Close
valve A. If needed, valve C can be closed
and valves A and B opened to recover
refrigerant in the hoses and charging
cylinder.
Step 5.
Use pinch-off tool to seal the
process tube between the drier and the
access valve. Remove the access valve
and braze the opening. After the required
five minute equalization time, start the
system compressor.
3.6 CHECKING OPERATION
The following general information explains several methods for checking operation of the
refrigeration system. The correct operation of a refrigeration system is dependent upon the
proper function of each of the parts comprising the system.
If the system does not operate properly (long run periods, warmer than normal temperatures),
the trouble may be caused by one of the following conditions:
(1) - Restricted Capillary Tube
The opening of a capillary tube is about the same diameter as the period at the end of this
sentence. Because of this, it is easy to restrict the tube. Extra precautions should be taken when
any service procedure involves moving or touching the capillary tube. The slightest kink can
cause a complete tube restriction.
Restrictions of the capillary tube may be caused by: (1) moisture freeze-up (R134a system), (2)
foreign particles lodged in the tube, or (3) a bend or kink.
If the capillary tube is restricted, there will be a noticeable lack of frost on all cooling surfaces; the
compressor may operate for a short period of time and cycle on the overload. When moisture
freeze-up causes a restriction, it usually occurs at the outlet end of the capillary tube. Normally,
frost buildup can be detected in this area.
At the discharge end of the capillary, apply heat by using the hairdryer. If there is enough head
pressure, and if the restriction is caused by moisture freeze-up, you will be able to hear a
gurgling noise as the heat releases the refrigerant through the tubing.
It is possible that this moisture will be absorbed by the filter drier and remedy the trouble.
However, if the freeze-up reoccurs, you must replace the filter drier.
A kink in the capillary tube will reveal the same symptom as a moisture freeze-up, except for the
