Thermo King CRR-40 119, Manual

Page: 151 / 170

151
Diagnosis
Mechanical Diagnosis
Condition Possible Cause Remedy
Compressor does not
operate- no amperage draw Controller ON; unit start sequence still
timing Wait up to 3 minutes for compressor
start-up
No Power to unit (condenser and
evaporator fans do not operate) Locate fault and repair: power source,
power plug, main circuit breaker, motor
contactor, motor terminals, motor
Open in 29 VAC control circuit Check fuses and On/Off switch. Replace
or repair as required.
Container temperature does not
demand compressor operation Adjust controller setpoint
Compressor contactor inoperative Replace compressor contactor
No output signal from controller Diagnose and replace main relay board
or controller
Unit on defrost Turn unit On/Off switch OFF and then
ON again
Defective high pressure cutout switch Replace high pressure cutout switch
High condenser head pressure
causing high pressure cutout Check refrigeration system and correct
fault
Defective compressor Replace compressor
Controller shut unit down on
Compressor Over Temperature (fault
code 56) Let compressor cool and controller will
reset automatically. Check liquid
injection valve and compressor
temperature sensor
Compressor motor internal thermal
overload protection open If compressor contactor is energized,
wait 60 minutes for protector to cool and
reset
Compressor does not
operate; excessive
amperage draw or
intermittent cycling on
overload
NOTE: Controller
sequence starts the
compressor when the unit
has been off for more than
18 hours.
Piston stuck Remove compressor head. Look for
broken valve and jammed parts
Seized or frozen compressor bearings Replace compressor
Improperly wired Check/correct wiring against wiring
diagram
Low line voltage Check line voltage-determine location of
voltage drop
High head pressure Eliminate cause of high head pressure
Contacts in compressor contactor not
closing completely Check by operating manually. Repair or
replace
Open circuit in compressor motor
winding Check motor stator connections. Check
stator winding for continuity. If open,
replace compressor
Defective compressor motor internal
thermal overload protector Replace thermal overload protector or
compressor