Diagnosis
163
Refrigeration Diagnosis
Evaporator fan motor(s) does
not operate
Unit on defrost
Check operating mode indicator
LEDs
Unit in Economy mode (Frozen Load;
Null mode only)
Check setpoint, indicator lights and
Program menu of µP-D controller to
verify that Economy mode is set to
On
Loose line connection Tighten connections
Open motor internal thermal overload
protector
Check for seized bearings or
defective thermal overload
protector. Repair or replace as
necessary
Defective motor Replace motor
Defective low or high speed
evaporator fan contactor
Replace defective contactor
No low or high speed evaporator fan
output signal from controller output
module
Diagnose and replace output
module or controller
Condition Possible Cause Remedy
Condition Possible Cause Remedy
Load temperature too high—
unit not cooling
Compressor does not operate See “Mechanical Diagnosis”
Controller setpoint too high Adjust controller setpoint
Defective container insulation or poor
fitting doors
Repair container
Shortage of refrigerant Repair leak and recharge
Overcharge of refrigerant Purge system
Air in refrigeration system Evacuate and recharge
Liquid injection valve open
Check liquid injection valve circuit
and compressor discharge
temperature sensor
Warm gas bypass valve open Check bypass valve circuit
Too much compressor oil in system
Remove compressor oil from
compressor
Iced or dirty evaporator coil Defrost or clean evaporator coil
Restricted lines on high side Clear restriction
Plugged filter drier/in-line filter Change filter drier
Stepper motor valve defective Replace defective valve
Condenser coil dirty or airflow
restricted
Clean condenser coil, clear
restriction, or repair or replace fan
motor or condenser fan blade
No water flow to water-cooled
condenser
Restore water flow to water-cooled
condenser-receiver tank
Defective water pressure switch
(Option)
Replace switch
Expansion valve open too much Adjust or replace valve
Expansion valve power element lost
its charge
Replace power element
Expansion valve feeler bulb
improperly mounted, poorly insulated
or making poor contact
Correct feeler bulb installation
To Next Page
Loading...
Need help?
General
