YORK INTERNATIONAL 97
FORM 150.40-NM25
SERVICE BULLETINS
CONVERTING FAN CONTROL TO DISCHARGE PRESSURE
Information is provided on page 36, column 2 and page 72, column 1 of this manual
to convert fan control to discharge pressure rather than temperature control for
extreme operating conditions. Step 1 in the 3-step conversion discusses re-adjust-
ing the Low Ambient Temperature Cut-out. Please make a note in the manual that
this adjustment cannot be made unless SW2 on the Micrologic Board is in the “ON”
position on REV C Micrologic Boards. This procedure mentioned also applies to
non-U.L. Chillers which may require fan cycling by discharge pressure.
Step 2 should also note that the OAT sensor should be replaced with a 50 KW
potentiometer. The pot should be adjusted to provide an OAT display of 15°F. Once
the 15°F display is obtained, the potentiometer resistance may be measured and
replaced with a fixed resistor.
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