MODEL PCA090480WH
CHAPTER 3
TROUBLESHOOTING
Section 5: Helpful Troubleshooting information
March 2013
3-5
Proprietary/Confidential
Page
85
© 2013 Twist, Inc.
1.
Shortage of Refrigerant
There should always be sufficient liquid in the condenser to completely fill the
liquid line. If there is a shortage of refrigerant, a mixture of gas and liquid will
pass into the expansion valve. Bubbles will appear in the sight glass: the
larger the bubbles the more severe the refrigerant shortage. Frequently there
will be a hissing or whistle at the expansion valve. The coil and suction line will
be relatively warm while the suction pressure will be low due to little or no
liquid being supplied to the evaporator.
2.
Identifying a Refrigerant Leak
Leaks may occur from line breakage due to vibration or other operating
malfunctions.
Use an electronic leak detector, if available, since it is the most effective form
of detection. The simplest and oldest method of leak detection is by means of
soap bubbles. Swab a suspected leak with liquid soap or detergent, and
bubbles will appear if a leak exists. Despite its simplicity, the soap bubble
method can be extremely helpful in pinpointing a leak that is difficult to locate.
This method will not pinpoint a very small leak.
3.
Air in the Refrigeration System
If air or other non-condensable gases are present in the system, they will tend
to move toward and collect at the condenser. The head pressure will rise to a
point above the pressure corresponding to the temperature at which the vapor
is condensing. In extreme cases, the pressure may rise to a point where either
the high-pressure cutout or the overload in the starter may stop the
compressor.
To determine whether or not there is air in the system, allow the compressor to
stand idle long enough for the entire system to cool down to the temperature of
the surrounding air. After the system has reached the same temperature as
the surrounding air, the reading of the head pressure gauge should not be
more than 10 lb. above the saturation pressure corresponding to the
surrounding air temperature. See the Appendix for R-407C
pressure/temperature relationship.
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