PGC, Inc 500-1000 CFM Air Handler May 2006
Appendix A A-12
TROUBLESHOOTING
CAUTION If the unit has a sight glass / moisture indicator, the hot gas bypass valve may cause
a false indication of low refrigerant charge if the valve is not closed at the time it is
being observed.
O
PERATING RANGE OF THE SYSTEM.
When the system will not control properly there are many potential causes. A basic understanding
of the operation of the system will assist in determining the cause of the problem.
1.) The air temperature will always be greater than the water temperature. Heat is
removed from the air only when the air passes through the water spray.
2.) The water temperature can approach freezing, but it must not be allowed to freeze;
the minimum water temperature is approximately 2.5°C (34.5°F). Since the dew
point is determined by the temperature of the water spray, the minimum dew point
will always be greater than the water temperature, thereby limiting the minimum
achievable dew point.
3.) All blowers, pumps and compressors operate at all times. If any of these items are not
operating, check for motor overload or failure or loose connections.
4.) Ambient conditions will limit operation of the unit. If the room temperature
surrounding the conditioner is too warm or humid, heat cannot be properly rejected
by the air cooled-condenser, affecting the chamber temperature and humidity.
NOTE
The system will not operate if the low-water level safety switch has opened due to
low water level in the sump.
W
ATER TEMPERATURE
1.) The refrigeration system controls the water temperature.
2.) If the water temperature is too high:
a. Check for proper condenser operation.
i. Is the condenser fan(s) operating?
ii. Is the condenser coil clean? During normal operation lint, dirt and debris
will deposit on the entering side of the condenser coil. This will reduce
the cooling capacity of the condenser which will reduce the refrigeration
capacity.
iii. Is the air flow path for the condenser clear? Obstructions such as boxes,
panels are walls can reduce the air flow across the condenser to the point
that it will reduce refrigeration capacity.
iv. Are all of the spray nozzles working? (All of the nozzles should have a
similar spray pattern. If the patterns vary, remove the nozzles and clean
the debris from the orifice)
v. Is the (optional) finned evaporator clean and free of debris?
b. Verify the operation of the refrigeration system
i. When the hot gas valve is fully closed (i.e., water set point is much less
than measured water temperature), the refrigeration sight glass should be
clear. Any bubbles in the sight glass will indicate a low refrigerant
charge.
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