TROUBLE SHOOTING CHART
SYMPTOM
CAUSES
CHECK & CORRECTIVE MEASURE
Head pressure too high
Head pressure too low
High suction pressure
Loss of oil pressure
Relay defective or burned out
Space temperature too high
Suction line frosted or sweating
Liquid line frosted or sweating
Unit noisy
1. Correct the refrigerant charge
2. Recharge the system after a thorough triple evacuation
3. Clean
4. Check and correct or replace
5. Check for short circuiting of condenser
discharge air, correct it
6. Correct it
1. Install fan cycling switch, if not provided.
Check the setting and operation, if provided
2. Correct the refrigerant charge after leak testing
3. Repair/replace the compressor
1. Check the design
2. Follow manufacture’s guide line and correct it
3. Repair/replace compressor
4. Check and adjust the superheat accordingly
5. Check the expansion valve bulb is properly
tighten at correct location
1. a. Correct the system piping
b. Trace out the wiring/defective controls/
components, etc. and correct it
c. Add oil
d. Check the superheat of expansion valve and
other possible causes like clogged filter, low
CFM, iced evaporator etc. and correct it
2. Check the system for correct superheat and
other possible causes like clogged filter, low
CFM, iced evaporator, etc.and correct it
3. Repair or replace it
4. Clean/replace it (oil change recommended)
1. Check and replace
2. Remount relay in correct position
3. Determine reason and correct
4. Determine reason and correct
5. Remount rigidly
1. Reset control
2. Use larger valve
3. Add surface or replace
4. Improve air movement
1. Re-adjust valve or replace with smaller valve
2. Clean valve from foreign particles, replace if necessary
3. Determine reason and correct
4. Correct charges
1. Replace it
2. Open valve fully
1. Find and tighten
2. Tighten the pipe support
3. Replace blade
4. Replace motor
1. Refrigerant overcharge
2. Air in system
3. Dirty condenser
4. Malfuction of condenser fan (air-cooled)
5. Excessive air temperature entering condenser
6. Restriction in discharge line
1. Low ambient temperatures (air-cooled)
2. Refrigerant shortage
3. Damaged valves in compressor
1. High load on evaporator, load in excess of
design conditions
2. Unbalanced system. Oversized air handling
unit matched with under sized condensing unit
3. Compressor discharge valve leaking
4. Expansion valve widely open
5. Improper bulb location or installation
1. Loss of oil from compressor due to:
a. Oil trapping in system
b. Compressor short cycling
c. Insufficient oil in system
d. Operation at excessively low pressure
2. Excessive liquid refrigerant returning to
compressor
3. Malfunctioning oil pump
4. Restriction in oil pump inlet screen
1. Incorrect relay
2. Incorrect mounting angle
3. Line voltage too high or too low
4. Excessive short cycling
5. Relay being influenced by loose mounting
1. Control setting too high
2. Expansion valve too small
3. Cooling coil too small
4. Inadequate air circulation
1. Expansion valve passing excess refrigerant or
is oversized
2. Expansion valve stuck open
3. Evaporator fan not running
4. Overcharge of refrigerant
1. Restriction in dehydrator or strainer
2. Liquid shut-off valve partially closed
1. Loose parts or mountings
2. Tubing rattle
3. Bent fan blade causing vibration
4. Fan motor bearings worn
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