Service manual

HEC-Series Service Manual
TROUBLESHOOTING
10/21/01
8-5
Symptom: Safety pressure switches stop machine.
Possible Cause Possible Remedy
Low pressure switch opens. Compressor suction service valve (34) may be either
closed or partially closed. Open valve wide. Check
switch for improper setting (too high opening pressure).
See Section 9, FIGURE 9-2.
High pressure switch opens. Compressor discharge service valve (35) closed or
partially closed. Open valve wide. Check cleanliness of
condenser. Check water supply to condenser. See Head
Pressure, Section 9.
A machine fault #10, 11, 12, or 13 has
occurred.
Enter the troubleshoot mode and identify the last
occurring fault. See Fault Identity, Section 6. Check
High/Low Pressure Switch, Section 9, FIGURE 9-2 for
improper setting (too low opening pressure). See Head
Pressure, Section 9. “X” (discharge line) solenoid valve
not opening (air-cooled units only). If the machine stops
by low pressure cut-out, the switch will reset
automatically when the pressure raises to the “cut-in”
setting. If it stops by high pressure cut-out, the switch
will have to be manually reset. After the switch is reset
(low pressure or high pressure), the PLC will initiate the
start-up mode for a two hour “time delayed” automatic
restart or the machine can be started immediately by
pushing the “Start” button.