Thermo King 098916, Maintenance Manual

Page: 119 / 196

Electrical Maintenance
118
High Pressure Cutout Switch
A high pressure cutout switch is located on the
compressor discharge service manifold of the
compressor. If the discharge pressure becomes too
high, the switch opens the ground circuit to the
compressor contactor coil:
• Compressor stops immediately. Evaporator
and condenser fans continue normal
operation.
• Controller determines that a high pressure
cutout switch or compressor motor internal
overload protector is open when the unit
current draw during compressor operation is
normal and then decreases by 7 amps for more
than 3 seconds.
• After 1 minute, controller LCD display shows
a High Pressure Cutout message:
• “HIGH PRESSURE CUTOUT CHECK
CONDENSER PROBE”: Water pressure
switch is open and the condenser
temperature is low.
• “HIGH PRESSURE CUTOUT CHECK
CONDENSER FAN”: Water pressure
switch is open and the condenser
temperature is high.
• “HIGH PRESSURE CUTOUT CHECK
WATER COOLING”: Water pressure
switch is closed.
• The controller continues to call for cooling so
the compressor will restart when the overload
condition is corrected (switch resets) if power
is available.
• If the switch remains open for 5 minutes, the
controller also turns on the Alarm LED and
records Alarm 37 (Total Power Consumption
Too Low).
High Pressure Cutout Switch:
• Opens: 3243 ± 7 kPa, 32.43 ± 0.48 bar, 470 ±
7 psig.
• Closes: 2586kPa, 25.9 bar, 375 psig.
To test the switch, rework a gauge manifold per
“High Pressure Cutout Manifold” illustration.
1. Low Pressure Cutout Switch
2. High Pressure Cutout Switch
Figure 64: Low and High Pressure Cutout Switches
1
2