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8-2
Mechanical Diagnosis
Diagnosis
CRR-20 & CRR-40, September 1999
Condition
Possible Cause
Remedy
Compressor does not
Piston stuck
Remove compressor head. Look for broken
operate; excessive
valve and jammed parts
amperage draw or
intermittent cycling
Seized or frozen compressor bearings
Replace compressor
on overload
Improperly wired
Check/correct wiring against wiring diagram
NOTE: Controller soft
starts the compressor
Low line voltage
Check line voltage — determine location of
after a heat or defrost
voltage drop
cycle, or when the unit
has been off for more
High head pressure
Eliminate cause of high head pressure
than 8 hours. See
“Sequence of Operation”
Contacts in compressor contactor not
Check by operating manually. Repair or
in
µµ
P-D Controller chapter
closing completely
replace
Open circuit in compressor motor
Check motor stator connections. Check
winding
stator winding for continuity. If open,
replace compressor
Defective compressor motor internal
Replace thermal overload protector or
thermal overload protector
compressor
Compressor contactor
Low line voltage
Increase line voltage to at least 90% of
burned out
compressor motor rating
Excessive line voltage
Reduce line voltage to at least 110% of
compressor motor rating
Short cycling
Eliminate cause of short cycling
Unit short cycles
Controller out of calibration
Recalibrate (see Diagnosis Manual for
Thermoguard
µ
P-D Microprocessor
Controller, TK 41230)
Refrigerant overcharge causing
Purge system
cycling on high pressure cutout
Inefficient condenser operation
Check condenser airflow, condenser
causing cycling on high pressure
fan motor, condenser fan grille, condenser
cutout
fan pressure switch, water pressure switch
(option), water flow rate (option) and \
water-cooled condenser-receiver tank
(option)
Содержание CRR-20
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