LG LFX25973 Series Service Manual page 60

12-4 Check D
D1. Activate Protection logic
- We have to check Condenser fan and Freezer fan before performing Check D
- Locked Piston, Current trip and stroke trip can be activated by other problems then the driver or compressor.
Locked piston
Stroke trip
Current trip
D2. sealed system diagnosis
- Check as follows;
Check for Oil leaks
In machine compartment
No
Check for oil
Yes
Remaining in drip tray
No
Check Temp of
Discharge line
and Condenser
No
Is there frost
on Suction Line?
No
Comp,Cond T >
Ambient temp+5deg
Yes
Sealed System
is OK
→ When process line on compressor is opened, and refrigerant is not expelled
High Pressure
because it has accumulated in condenser.
Side
→ If fault is corrected after refrigerant is recaptured from sealed system, change
Restricted
dryer.
→ Low side restriction can cause a stroke trip.
Low
→ If fault is corrected after refrigerant is recaptured, perform a sealed
Side
system evacuation and dryer replacement.
Restriction
→ Check Suction line
→ If refrigerant is overcharged and suction line temperature is lower
Over charging
Refrigerant
than ambient temperature (about 5~10 degrees) or frost is present
150mm from where the suction line enters the compressor..
→ Temp. of compressor and discharge line is normal to slightly higher.
High side pressure is normal to slightly higher than normal
Low side
conditions. This is because condenser cannot condense the air
Refrigeration
that is trapped in the condenser. The high side pressure and
leak
temperature will not mimic the low side pressures and
temperatures.
→ Customer complains of longer run times and poor cooling performance.
→ Lack of refrigerant can, in some incidents, cause piston over travel.
Refrigerant leak → Pressure of refrigerant cycle is usually higher than ambient pressure,
therefore oil will flow out with the refrigerant at leak point.
Yes
Repair leak
at point where
Oil is present.
Check for Oil leakage
at each joint
of the Evaporator
A
Check frost status
Yes
No
Heavy repair
A
Cycle check with protection logic
A
In/Out Leakage
Evaporator
Leakage Evaporator
Frost only
Evaporator inlet
Of Evaporator
Is frost pattern
uniform?
Yes
Sealed System
is OK
- 60 -
Sealed system
Welding point
A
1. Comp process stub,
2. Comp discharge
Replace
A 3. Hot Line inlet
4. Drier inlet
5. Drier outlet
6. Evaporator inlet
7. Evaporator outlet
8. suction pipe
Heat Inlet tubing
using heat gun.
No
Is frost patern
Uniform?
Yes
OK
A