Thermo Scientific Jewett CTF306 Installation And Operation Manual page 13

Thermo Scientific Jewett CTF306 Blood Plasma Freezers
TROUBLESHOOTING SERVICE CHART
SYMPTOM
High suction
J pressure.
Low suction
K pressure.
Suction line
L
frosted or
sweating.
Liquid line
M
frosted or
sweating
Ice
N
accumulating
on ceiling
around
evaporator
and/or on fan
guards or
blades.
Evaporator
O coil not
clearing of
frost during
defrost cycle.
Ice
P
accumulating
in drain pan.
NOTE: Jewett Refrigerators and Freezers are designed to operate in areas that are heated to 60° F (15.6° C). Installation in
unheated areas may require a low temperature compressor protection kit for satisfactory operation.
POSSIBLE CAUSE
1. Excessive load.
2. Expansion valve overfeeding.
1. Insufficient refrigerant in system.
2. Restriction in refrigeration system. Most
notably the liquid line filter drier or
capillary.
3. Expansion valve malfunctioning.
1. Expansion valve passing excess
refrigerant or is oversized.
2. Expansion valve stuck open.
3. Evaporator fan motors not running.
4. System overcharged with refrigerant.
1. Restriction in liquid line filter drier.
2. Liquid line shutoff valve partially closed. 2. Open valve.
1. Defrost duration too long.
2. Fan delay not delaying fans after defrost
period.
3. Defective timer.
4. Too many defrost cycles per day.
1. Coil temperature not getting above
freezing point during defrost.
2. Not enough defrost cycles per day.
3. Defrost cycle too short.
4. Poor door seal.
5. Defective timer or defrost thermostat.
1. Defective heater.
2.Unit not pitched properly.
3. Drain line plugged.
4. Defective drain line heater.
5. Poor contact between drain pan and
heater element.
6. Defective timer or defrost thermostat.
Installation and Operation
POSSIBLE CORRECTIVE STEP
1. Reduce load or add additional equipment.
2. Check remote bulb. Adjust superheat.
1. Check for leaks. Repair and add charge.
2. Determine location and remove.
3. Check and reset for proper superheat.
1. Readjust valve or replace with smaller
valve.
2. Clean valve of foreign particles, and
replace if necessary.
3. Determine reason and correct. Check
door switch.
4. Correct the charge.
1. Determine location and remove.
1.Adjust defrost termination.
2. Defective fan delay thermostat. Replace.
3. Replace.
4. Adjust timer for less defrost cycles.
1. Check heater operation, or hot gas
solenoid valve.
2. Adjust timer for more defrost cycles.
3. Adjust timer for longer defrost cycle.
4. Adjust door latch, install new gasket.
5. Replace defective component.
1. Replace heater.
2. Check and adjust if necessary.
3. Clean drain line.
4. Replace heater.
5. Repair.
6. Replace defective component.
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