Carrier 19XL - Manual (Page 182)

Carefully make all regular preliminary and running system checks. Perform a Control Test
before start-up. If the compressor oil level appears abnormally high, the oil may have absorbed
refrigerant. Make sure that the oil temperature is above 140 F (60 C) or cooler refrigerant
temperature plus 50° F (27° C).
Cold Weather Operation
When the entering condenser water drops very low, the operator should automatically cycle
the cooling tower fans off to keep the temperature up. Piping may also be arranged to bypass
the cooling tower. The PIC controls have a low limit tower fan relay (PR3) that can be used to
assist in this control.
Manual Guide Vane Operation
Manual operation of the guide vanes in order to check control operation or control of the
guide vanes in an emergency operation is possible by overriding the target guide vane position.
Access the Status01 table on the LID and highlight TARGET GUIDE VANE POSITION . To
control the position, enter a percentage of guide vane opening that is desired. Zero percent is
fully closed, 100% is fully open. To release the guide vanes to AUTOMATIC mode, press the
RELEASE softkey.
Note: Manual control will increase the guide vanes and override the pulldown rate during start-
up. Motor current above the electrical demand setting, capacity overrides, and chilled
water below control point will override the manual target and close the guide vanes. For
descriptions of capacity overrides and set points, see the Controls section.