English
7
Troubleshooting
CP
compressor
thermal protection
alarm
Compressor
High current
noisy
absorption
Compressor
No
Condenser dirty or
components
obstructed
perished
Yes
Th e compressor
works in the oppo-
Yes
site direction
Yes
No
invert
the phases
Compressor
fault
Yes
Repair or
Compressor
Yes
replace
winding with
compressor
partial loss of
Z
insulation
No
FAULT
Lt Low evaporation
temperature alarm Ld
pressure alarm
Low dew point alarm.
LP
Yes
Clean
Low pressure
condenser
switch fault
Yes
Low
Increase
cooling
cooling air
air
temperature
temperature
No
Replace
Fan
Yes
pressure
always
switch
working
Z
(PV pressure
switch fault)
Liquid line
solenoid valve
No
closed
Hot gas
Yes
valve
Yes
not calibrated
Replace
Calibrate
the coil
valve
Z
No
Z
PST 390-1980
REMEDY
CAUSE
LP Low
High dew point re-
frigeration compressor
operating?
Replace
Yes
pressure
switch
Z
No
Excessive thermal load
(air fl ow, inlet temperature)
No
Replace
Fan pressure
Yes
pressure
switch (PV)
switch
not set
Z
No
No
Low current
Yes
refrigerant
absorption
recharge
Z
No
No
Request external
assistance
ST thermostat tripped
Decrease
Yes
Cooling air high
cooling air tem-
temperature
perature
No
Decrease
Yes
compressed air
quantity tempe-
rature
No
Conden-
Yes
Clean
ser dirty or
condenser
obstructed
No
Replace pressu-
Yes
Low current
Z
re switch
absorption
No
Replace
fan
Z
6/6
HP pressure switch
tripped
Yes
Cooling air high
temperature
No
Excessive thermal
Yes
load (inlet air fl ow,
temperature)
No
Yes
Condenser dirty or
obstructed
No
Fan does
Yes
not turn (PV pres-
sure switch fault)
No
Yes
Fan fault
No