Daewoo Frs U20 Service Manual

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Remarks
●Refrigerant is erupting rapidly from the compressor to circulate pipes, so pipe shaking noise
can make to some degree.
●In case compressor vibration is sent to a pipe directly, apply vibration absorber rubbers to welding
points of the pipe and comp. or to a much bent point on the pipe.
Start
Separate the touching
pipes, if any. NY
Apply cushion material between
Comp. base and Tray drip. YN
Move or change the points of
vibration absorber rubbers on
the pipes to reduce the shaking. YN
Attach a absorber
on the comp. head. NY
Explanation to the users. 9-4-4. Pipe Noise
Pipes are touching
in the machine compartment ?
Tray drip makes
noise by Condenser shaking ?
Pipe itself is
shaking much ?
Compressor itself
is shaking much ?
 
						

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Door switch is soaked with
water or there is water in
the switch ?
PCB input is OK ?
Start
Change the door switch.
NY
Repair any disconnection
of wires and defective
Door switch. Y
Connector insertion to
Main PCB is OK ?N
Repair the defective
connection.
Y
Door switch itself is 
OK ?N
Change the switch.
NY
Check it up.
Door switch is pushed 
well ?
Y
Attach a thin pad on the
door liner or change the
door assembly.
Check if interior light is ON.
N
9-5. Door 
9-5-1. Door Opening Alarm Continues though the door is closed.
Check #5,6 of CN8 (F-Door) 
and  #4,6 of CN7 (F-Door).
→Open : 5V, Close : 0V
 
						

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10-1. Summary of Heavy Repair
* Installation should be conducted in accordance with
the standard installation procedure. (Leave space of
more than 5 cm from the wall for compressor
compartment cooling fan mounted model.) Transportation
and
installation* Copper brush, Rag, Tool box * Remove flux from the silver weld joints with soft 
brusher wet rag. (Flux may be the cause of corrosion
and leaks.)
*Clean tools and store them in a clean tool box
or in their place. Compressor
compartment
and tools
arrangement* Electronic Leak Detector,
Driver. *  Check leak at weld joints.
Note :Do not use soapy water for check.
* Check cooling capacity
→Check condenser manually to see if warm.
→Check hot pipe manually to see if warm.
→Check frost formation on the whole surface of the
evaporator. Check
refrigerant leak
and cooling
capacity* Bombe (mass cylinder),
refrigerant manifold gauge,
electronic scales, punching
off flier, gas welding machine * Weigh and control the bombe in a vacuum conditions
with electronic scales and charge through compressor
inlet (Process tube).
* Charge while refrigerator operates).
* Weld carefully after inlet pinching. Refrigerant
charging and
charging
inlet welding* Vacuum pump 
, Manifold gauge. * Evacuate for more than forty minutes after connecting
manifold gauge hose and vacuum pump to high (drier)
and low (compressor) pressure sides. Vacuum* Pipe Cutter, Gas welder,
N2 gas * Confirm refrigerant (R-134a or R-600a) and oil for 
compressor and drier.
* Confirm N2 sealing and packing conditions before use.
Use good one for welding and assembly.
* Weld under nitrogen gas atmosphere.
* Repair in a clean and dry place. Parts
replacement
and welding* Nipper, side cutters * Cut charging pipe ends (Comp. & Dryer) and
discharge refrigerant from drier and compressor. Remove 
refrigerant
ResidualsTools Contents Process
10. COOLING CYCLE HEAVY REPAIR
 
						

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1) Nitrogen only should be used when cleaning inside of cycle pipes
inside and sealing.
2) Check leakage with an electronic leakage tester.
3) Be sure to use a pipe cutter when cutting pipes.
4) Be careful not the water let intrude into the inside of the cycle. Others.1) Weld under nitrogen atmosphere in order to prevent oxidation
inside a pipe. (Nitrogen pressure : 0.1~0.2 kg/cm2.) Nitrogen blowing
welding.1) Be sure to replace drier when repairing pipes
and injecting refrigerant. Replacement of drier.1) Remove retained refrigerant more than 5 minutes after turning off 
a refrigerator. (If not, oil will leak inside.)
2) Remove retained refrigerant by cutting first high pressure side
(drier part) with a nipper and then cut low pressure side.
(If the order is not observed, oil leak will happen.) Removal of retained
refrigerant.1) Use special parts and tools for R-134a or R-600a Use of tools.Precautions Items
10-2. Precautions During Heavy Repair
Process tubeCompressorEvaporator
Dryer
High Pressure side
Low pressure
side 
Suction tube
Discharge tubeCondenserHot Pipe
 
						

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1) Remove residual refrigerant more than 5 minutes later after
turning off the refrigerator. ( If not, compressor oil may leak inside.)
2) Remove retained refrigerant slowly by cutting first high pressure
side (drier part) with a nipper and then cut low pressure side. 1. Removal of residual
refrigerant.Precautions Items
10-3. Practical Work for Heavy Repair
* When replacing a drier:
Weld ①and②parts by blowing nitrogen (0.1~0.2kg/cm2) to high
pressure side after assembling a drier.
* When replacing a compressor:
Weld ③and④parts by blowing nitrogen to the low pressure side.
Note) For other parts, nitrogen blowing is not necessary because it
does not produce oxidized scales inside pipe because of its short
welding time. 2. Nitrogen blowing
welding.
※KEYPOINTING
Welding without nitrogen blowing produces oxidized scales inside
a pipe, Which affect on performance and reliability of a product.
Process tubeCompressorEvaporator
Dryer
High Pressure side
Low pressure
side 
Suction tube
Discharge tubeCondenserHot Pipe
Process tubeCompressorEvaporator
Dryer
High Pressure side
Low pressure
side ①
Condenser②
③ ④
Hot Pipe
 
						

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* Pipe Connection
Connect a red hose to the high pressure side and a blue hose
to the low pressure side.
* Vacuum Sequence
Open ①,②valves and evacuate for 40 minutes.
Close valve ①. 3.Vacuum degassing.Precautions Items
* Charging sequence
1) Check the amount of refrigerant supplied to each model after
completing vacuum degassing.
2) Evacuate bombe with a vacuum pump.
3) Measure the amount of refrigerant charged.
- Measure the weight of an evacuated bombe with an electronic scale.
- Charge refrigerant into a bombe and measure the weight. Calculate
the weight of refrigerant charged into the bombe by subtracting the
weight of an evacuated bombe. 4.Refrigerant charging.
CompressorEvaporator
Dryer Condenser
Vaccum
PumpHot Pipe
Blue
Yellow
Red High
Pressure Low
Pressure
①
②
※KEYPOINTING
1) If power is applied during vacuum degassing, vacuum degassing
shall be more effective.
2) Operate compressor while charging refrigerant. (It is easier and
more certain to do like this.)
the amount of refrigerant charged
= a weight after charging 
- a weight before charging
(a weight of an evacuated cylinder)
Calculation of amount of refrigerant charged ※KEYPOINTING
1) Be sure to charge
the refrigerant at
around 25°C.
2) Be sure to keep
-5g in the winter
and +5g in summer.
Indicate the weight of
an evacuated bombe
 
						

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Precautions Items
4) Refrigerant Charging
Charge refrigerant while operating a compressor as shown above.
5) Pinch a charging pipe with a pinch-off plier after completion of charging.
6) Braze the end of a pinched charging pipe with copper brazer and take
a gas leakage test on the welded parts. 4.Refrigerant charging.
BombeCompressorEvaporator
CondenserDryer Hot Pipe
* Take a leakage test on the welded or suspicious area with an
electronic leakage tester. 5. Gas-leakage test
* Check each pipe is placed in its original place before closing
a cover back-M/C after completion of work. 6. Pipe arrangement
in each cycle
10-4. Standard Regulations for Heavy Repair
1) Observe the safety precautions for gas handling.
2) Use JIG (or wet towel) in order to prevent electric wires from burning during welding.
(In order to prevent insulation break and accident.)
3) The inner case shall be melted and insulation material (polyurethane) shall be burnt 
if not cared during welding inner case parts.
4) The copper pipe shall be oxidized by overheating if not cared during welding.
5) Not allow the aluminum pipes to contact to copper pipes. (In order to prevent corrosion.)
6) Make sure that the inner diameter should not be distorted while cutting a capillary tube.
7) Be sure that a suction pipe and a filling tube should not be substituted each other during welding.
( High efficiency pump.)
 
						

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10-5. Brazing Reference Drawings.
▶Welding Point
●
■Copper Welding (Ag 5%)7 Points
3 Points Silver Welding (Ag 35%)
Hot Pipe
F
REvaporator
CondenserI-Pipe
Accumulator
Suction Pipe
Dryer
Capi-Tube
Pipe Suc Conn
Pipe Conn B
Compressor
▶Flow of Refrigeration Cycle
Compressor
Pipe Conn. BWire-Con. Pipe
Hot PipeDryer
Capillary Tube
EvaporatorAccumulator
Pipe Suction Conn
Suction Pipe
HighLow
 
						

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11-1. Installation Preparation
11. INSTALLATION GUIDE
Check if the refrigerator can pass
a doorway or enter a door first. 
Dimensions( including Door Handles)
(Width*Depth*Height)     
903mm X 734.5mm X 1790mm
Find a suitable place to install
Sufficient space from refrigerator back to the
※wall for free air ventilation※Avoid direct sunlight.
Once the installation place is ready follow the installation instructions.
If surround temperature of refrigerator is low (below 10℃)), 
foods can be frozen or the refrigerator can work in abnormal way.
 
						

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11-2. If the refrigerator can not enter the door
Removing Freezer Door 
1
※Remove front bottom cover first, if it is attached.
Remove front bottom cover first,
Pull out the left collar of the 
coupling first, then hold the 
coupling and pull out the left 
water tube.2Unscrew top hinge cover with a
screw driver.
Remove the hinge cover.3Turn top hinge bolt
counterclockwise . 
Disconnect the harness wires.
4Lift up the front of hinge to remove. 
( After the hinge is removed the
door can fall down forward.
Be careful !)5Be careful not to damage the
water line when removing the
door.
Removing Refrigerator Door 
1Unscrew top hinge cover with a
screw driver.
Remove the hinge cover.2Turn top hinge fastener
counterclockwise. 
Disconnect harness wires.3Lift up the front of hinge to remove.
(After the hinge is removed the
door can fall down forward.
Be careful !)
4Lift the door straight up to remove.