VOGT ICE TUBE-ICE P-24A, Service Manual

Page: 90 / 146

P24A & P34A Service Manual
SERVICING OPERATIONS
12/18/12
9-4
Compressor Crankcase Heater.
When electrical power is supplied to terminals 12 and 22 of the
control panel (see Figure 6-3), the crankcase heater is energized when the compressor is not running.
It is deenergized when the compressor is operating. Adjust the heater to maintain a temperature of
the oil in the crankcase at 100-110
° F (38-43 ° C) when the compressor is not running. This will
prevent the migration of refrigerant to the compressor during off periods.
Oil Pressure Switch.
The compressor is protected by a manual reset type low oil pressure safety
switch which is set at 15 psig. The oil pressure switch has a built-in 60 second time delay. If the net
oil pressure (pump pressure minus suction pressure equals net oil pressure) falls below the switch
setting for a time period of 60 seconds and the pressure does not increase at least 5 psi above the
setting during that 60 seconds, the switch contact will open and stop the machine. After a period of
time as the delay heater cools, the switch can be manually reset and the machine restarted. The
compressor should not be operated under low oil pressure or low oil level conditions.
If oil is added to the compressor crankcase to resume operation after a loss of oil, be sure to observe
several cycles to make sure the oil level remains stable. See “Troubleshooting”, “Low Oil Pressure
Switch Tripped”.
If it is necessary to install a new oil pressure switch, see FIGURE 9-4 for adjusting.
! CAUTION !
When this switch causes the machine to stop, the cause should be identified
and corrected before resuming operation.
! CAUTION !
FIGURE 9-4
Oil Pressure Switch
Control Circuit Protection.
The electrical control circuit of the machine is protected by a 6 amp
circuit breaker (CB4). If this breaker should open, the machine will immediately stop. Before
resetting the circuit breaker, open the disconnect switch and lock-out all power to the control panel.
Reset CB4 and restore power. Check circuitry with a volt meter. If the machine was off for an
extended time, the crankcase heater must be energized for a minimum of four (4) hours and no liquid
refrigerant in the crankcase before restarting the machine. When ready to restart the machine,
depress the “Start” button. As usual, initiate a harvest cycle if there is ice remaining in the freezer.
Check Amp draw through the breaker for excessive load or unbalance.