10TA Service Manual
TROUBLESHOOTING
4/23/14
8-9
SYMPTOM:
High head pressure. (Water cooled machine)
POSSIBLE CAUSE POSSIBLE REMEDY
Misadjusted or defective water regulating
valve
Adjust or replace the valve. Never adjust the
valve stem as far open as it will turn, because it
will not close when the head pressure drops.
Insufficient water supply. Check size of water line and pump output at the
condenser. Refer to the specification sheet for
water requirements. Check cooling tower sump
level and make-up water supply.
Cooling tower needing maintenance. Check cooling tower fan belt and tighten or
replace as needed. Check spray nozzles and
sump screen and clean as needed.
Non-condensables (usually air) in system. Check refrigerant tables for
pressure/temperature relation. If non-
condensables are present, Perform a total
pumpdown, let stand for at least 6 hours,
allowing non-condensables to gather in the
upper part of the receiver. Evacuate the freezer
and attach a recovery unit to the top receiver
purge valve (59). Open the valve and recover
the vapor for about five minutes. When the
freezer is evacuated, open the thaw gas solenoid
valve manually for about 15 seconds letting the
top vapor in the receiver blow into the freezer.
Close the solenoid valve and evacuate the
freezer again. Evacuate to 500 microns and
restart the machine.
Fouled (dirty) condenser. Follow the diagnostic procedure outlined in,
Section 7, and clean the condenser per
instructions under Condenser Cleaning,
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