Schreiber Chillers 15MEDAC_GEN2 - Manual (Page 35)

SPECIAL INSTRUCTIONS
ELECTRICAL CONTROLS- Control Circuit 24 Volts
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
cut out occurred, 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 compressor switch. It is used to OPERATE the refrigeration
system.
The fourth part on the circuit is motor overload protected. Every motor is equipped with an internal
overload or external over-current protection. Motor overload cut out can be due to various reasons.
In most cases, it is either caused by over or under supply voltage.