Schreiber Chillers 1000AC-MRI - Manual (Page 17)

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. 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 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.
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 water 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. It 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. Since antifreeze is a poor conductor of heat, never add more than
necessary.
The third control on the circuit is the manual compressor switch. It is only used to turn
the refrigeration system on or off.
The fourth part on the circuit is the overload protection on the compressor. It will open if
the unit becomes low on refrigeration or if the improper voltage is used. This part of the
circuit is an automatic reset.
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