Emerson DH Manuel D’Utilisation

Refrigerant flooding

Defective or improperly set 

expansion valve

Increase superheat or replace valve

Evaporator fan motor or belt

Correct problem or replace fan motor and/or belts.

Low condensing pressure

Check head pressure control device

Slipping belts

Inspect and adjust

Blown valve plate or 

cylinder head in comp.

Liquid refrigerant floodback or 

flooded start

See Symptom: Flooding

Low compressor 

capacity or inability to 

pull down system

Blown valve plate or cylinder 

head gasket.

Replace gaskets. Retorque cylinder head bolts to 

compressor manufacturer's specs.

Leaky valve plate or worn valve 

seats

Replace valve plate assembly

Leaky suction valves

Pump down, remove cylinder head examine valve and valve 

seats. Replace if necessary

Broken connecting rods or 

pistons

Replace compressor.

Leaking liquid line solenoid valve 

or dirt in valve

Replace valve if clean; clean out valve if dirty.

Compressor noisy

Slugging due to floodback of 

refrigerant

See Symptom: Flooding

Bearings wiped because of loss 

of oil

See Oil Pressure. Check for defective oil failure control.

Loose compressor or piping 

support

Tighten clamps.

Broken connecting rods, valves 

or other running gear

Replace compressor

Pipe rattle

Loose pipe connections

Check pipe connections

Compressor running hot

Blown valve plate or cylinder 

head gasket

See Symptom: Blown Valve Plate

Broken suction or discharge 

valve

Replace valves and valve plate, if necessary.

Compression ratio too high

Check setting of high and low pressure switches. Check 

condenser-- is it plugged? Check that all evaporator and 

condenser fans are operating properly.

Excessive blow-by into 

crankcase -work rings, valves, or 

blown gasket

Replace gasket, valve plate, or compressor

Compressor cycles 

intermittently

Low-pressure switch erratic in 

operation

Check tubing to switch to see if clogged or crimped Check 

for proper switch operation

Insufficient refrigerant in system

Check for leaks, fix, and add refrigerant

Suction service valve closed

Open valve.

Insufficient water flowing through 

condenser or clogged 

condenser, or dirty air cooled 

condenser coils

Adjust water regulating valve to condenser. Clean 

condenser.

Discharge service valve not fully 

open

Open valve