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Symptom Cause Remedy
Low 1. Insufficient refrigerant in system 1. Check for leaks. Repair and add charge
discharge 2. Faulty condenser temp. regulation 2. Check condenser control operation
pressure 3. Compressor suction or discharge valve 3. Clean or replace leaky valve plates
inefficiencies.
4. Low suction pressure 4. See corrective steps for low suction pressure
5. Head pressure control valve set wrong 5. Adjust valve or install a head pressure
or no head pressure control valve control valve.
High suction 1. Excessive load 1. Reduce load or add additional equipment
pressure 2. Expansion valve overfeeding 2. Check remote bulb. Regulate superheat.
Low suction 1. Lack of refrigerant 1. Check for leaks. Repair and add charge
pressure 2. Evaporator dirty or iced. 2. Defrost or clean coil
3. Clogged liquid line filter drier 3. Replace cartridge(s)
4. Clogged suction line or compressor 4. Clean strainer or replace filters
suction strainer
5. Expansion valve malfunctioning 5. Check and reset for proper superheat
6. Condensing temperature too low 6. Check means for regulating
condensing temperature
7. Improper TXV 7. Check for proper sizing
Little or No 1. Clogged suction oil strainer 1. Clean
oil pressure 2. Excessive liquid in crankcase 2. Check crankcase heater. Reset TXV for
higher superheat. Check liquid line solenoid
valve for proper operation.
3. Low oil pressure safety switch defective 3. Replace
4. Worn oil pump 4. Replace
5. Oil pump reversing gear stuck in 5. Reverse direction of compressor rotation
the wrong position.
6. Low oil level 6. Determine where the oil is or add oil.
7. Worn bearings 7. Replace compressor
8. Loose fitting on oil lines 8. Check and tighten fittings
9. Pump house gasket leaks. 9. Replace gasket
Compressor 1. Lack of refrigerant 1. Check for leaks. Repair and add charge
loses oil 2. Excessive compression ring blowby 2. Replace compressor
3. Refrigerant floods back 3. Maintain proper superheat at compressor
4. Improper piping or traps 4. correct piping
Compressor 1. Operating beyond design limits 1. Add facilities so that conditions are within
thermal allowable limits.
protector 2. Discharge valve partially shut 2. Open valve
switch open 3. Blown valve plate gasket 3. Replace gasket
4. Dirty condenser coil 4. Clean coil
5. Overcharged system 5. Reduce charge