Schreiber Chillers 750ACsf - Manual (Page 13)

SPECIAL INSTRUCTIONS
WATER PUMP
The water pump is controlled by the manual switch for off and on operations. The motor
on this pump has a built-in overload protection, as do all the motors in our system.
ELECTRICAL CONTROLS - Control Circuit 24 Volts
The control circuit for the refrigeration system has several controls wired in series. First
are the high and low-pressure switches that are mounted in the control panel. The high-
pressure switch will shut off the refrigeration system in the event the pressure is too
high. High pressure can be caused by the condenser becoming restricted, by foreign
material on the outside surface of the condenser, or if the fan motor is not running, or
service access panel are not in place. If the high-pressure limit switch should cut out,
there is a manual reset switch, which is located at the control panel on the right side. In
order to reset this switch, the disconnect switch and the manual switch must be turned
off and the control panel door must be open. If and when the high-pressure switch is off,
check the "Trouble Shooting" chart for diagnosis. (There must be a reason.)
The low-pressure switch will cut out at any time the pressure in the refrigeration system
is below 25 psi. Low psi can be caused by a freeze up in the tank, a leak in the
refrigeration system, if the system is low on Freon (R-22), or if there is any sort of
restriction in the system. If the switch cuts out, it will automatically reset. NEVER TRY
TO ADJUST THE HIGH AND LOW PRESSURE SWITCHES or by-pass them, or
serious damage to the system will result. Adjustment should only be made after the
internal pressure of the refrigeration system has been read.
The second control of the circuit is the temperature controller. The solid-state control
panel controls the cycling of the refrigeration system. Once this control is set, it will
control the cycling of the unit automatically. Do not set it below freezing unless the
proper amount of antifreeze is put into the unit. Because antifreeze is a poor conductor
of heat, never add more than necessary.