Vogt
®
VT Service Manual 7-3
Troubleshooting
MACHINE INOPERATIVE
No Electrical Power:
Check main electrical fused disconnect or circuit breaker. If power has been off,
crankcase heater should be energized two (2) hours prior to starting.
Note: If no power to the lowside unit, check 10A breaker in condensing unit electrical enclosure.
High Pressure Safety:
Reset high pressure control switch. If tripped, install gauges observe operating
pressures to determine that compressor discharge pressure is within operating limits. If fans do not come
“on”, check circuit breaker in condensing unit control panel. For water cooled units, verify water supply and
water regulating valve setting.
Low Pressure Safety:
This switch will automatically reset when pressure comes up to the “cut-in” set
point. If tripped, install gauges observe operating pressures to determine that compressor suction pressure is
within operating limits. If suction pressure is low, check machine refrigerant charge.
Note: When the machine starts after a power failure or after the machine has cycled off on bin control or the
“on/off/clean” selector switch, the PLC do not look at the low pressure switch for 90 seconds.
Compressor Motor Overload Protector
(Sentronic before March 2011, CoreSense after March
2011)
:
Machines are equipped with a compressor protection device that opens in the event compressor
temperature or amperage reaches an extreme that could damage compressor. The device automatically
resets after compressor has cooled. CoreSense must be reset.
(Note: On VT80 & V100 Only). Note: This sensor is in series with the oil pressure safety switch. Fault #3 can
be either compressor motor overload or oil pressure.
CAUTION: If machine is off on motor overload protector, control cycle timer and
other components will continue to function although the compressor is off. The
machine or any of its components can start without warning causing serious injury.
Bin Control Open:
Adjust thermostat bin control as required. See page 8-3 for bin control error code.
Faulty Remote Off/On Switch:
Replace if necessary.
Compressor Contactor Defective:
Check wiring to line contactor to determine that "L" terminals
are supplied with power. Check contactor coil for open winding.
Oil Failure Switch
(Sentronic before March 2011, CoreSense after March 2011): Reset Sentronic oil
pressure safety switch. Check compressor oil level. If oil level in sightglass, check oil pressure.
Note: Verify proper operation of crankcase heater. Cold starts can cause oil loss.
Chopper Failure:
If the chopper motor fails to come on, the current sensing relay in the chopper motor
circuit will detect the absence of motor current and shut the machine off. See Machine “Freeze-Up”.
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