Tuesday 27 March 2018

Electrolux Frost free refrigerator DEF37 – Argentina - Troubleshooting - wiring and electrical schematic


Electrolux Frost free refrigerator DEF37/40/44 – Argentina 
Fine Adjustment of Freezer Compartment Temperature
This refrigerator was produced within international standards and has 4 temperature levels with factory preset values and can be adjusted (decrease or increase) according to your need. Case want to alter the values, there is the possibility of fine adjustment of temperature for the 4 temperature levels.
To program this function:
1. Press simultaneously the "DISARM ALARM" and "TEMP. FREEZER "until you hear one sound signal, then it will turn on the "MIN" indicator in the control panel.
2. Adjustment Options (within 5 seconds to program the Fine Adjustment):
To raise (warmer) 0.5 ° C at the preset temperature press the "DISCONNECT" key once ALARM".
Note: After the beep you will have 5 seconds to program Fine Adjustment. After This period will be issued a new sound signal indicating that the time of 5 seconds for adjustment was
Finalized.
To raise (warmer) 1.0 ° C at the preset temperature, press the "DISCONNECT" key twice ALARM"
To lower (colder) 0.5 ° C at the preset temperature, press the "TEMP. FREEZER ".
To lower (colder) 1.0 ° C at the preset temperature, press the "TEMP. FREEZER "
To verify which the last adjustment was made:
Press the "DISPLAY" keys simultaneously. ALARM "and" TEMP. FREEZER "until you hear a beep and will light the indication of the last adjustment made.  Since being accessed, the programmed Fine Temperature Adjustment is valid for the 4 levels of temperature.
Functioning
The DFF37 / 40/44 Frost Free Electronic refrigerators work under the gas compression cycle. The fluid is compressed in the alternative compressor, releases heat in the skin type condenser, suffers restriction in the capillary tube and absorbs heat in the finned tube evaporator. Return to the compressor through the suction line.  The cold air coming from the evaporator is forced by the motor-fan in the freezer and driven for the Refrigerator through a thermostatic damper.
The temperature control in the freezer is made by means of a temperature sensor (thermistor) located in this compartment, which according to the registered temperature, suffers variation in its electrical resistance, generating a voltage drop that is received by the main board.  The board, processing this information and according to the regulation of the product, connects or disconnects both the compressor as the motor-fan, according to the need or not of cooling.
The temperature control in the refrigerator compartment is made through the activation of the button regulation directly on a thermostatic Damper that allows total or restrictive passage of refrigerated air coming from the freezer.
When connecting the product to an outlet with adequate voltage (220V), a self-diagnosis of components is done and all the LEDs in the panel remain on for two seconds.
No abnormalities are detected, three more seconds will pass before the compressor and the motor fan enter in operation (the motor fan only works with the two door switches closed) running for five minutes regardless of temperature conditions. In those 3 The defrost heaters are activated for a test run.
If there is no temperature adjustment in the box, the product will work automatically regulated in the middle position (central position in the FREEZER TEMP indicator in the box).
Thaw
After some time of cooling, all moisture inserted in the product, coming from food or of the opening of doors, will be retained in the evaporator, freezing gradually. There is then the need to remove this ice from the surface of the evaporator, in a melting operation.
The product has a defrosting resistance added to the evaporator. There is also a resistance adhered to the drainage channel of the thaw, preventing some freezing at this point. The resistance
The evaporator and the channel are connected in parallel.
During the defrosting function, the compressor and fan will remain disconnected.
The activation of the resistors is done by the printed circuit board, with the control of defrosting monitored by the defrost sensor. There is a safety thermal fuse, positioned on the evaporator.
Obs: The thermal fuse acts only in case of failure in one of the other circuits, preventing the resistance of thawing hot too much. If the thermal fuse is activated, it will not be used.
Before the replacement of this component, the cause of the problem must be identified and corrected obligatorily
The product must never be connected without the thermal fuse being properly installed.
De-icing sensor registering a temperature equal to or above 12ºC when the refrigerator.
De-icing sensor registering a temperature lower than 12 ° C when the refrigerator is connected (in case of any lack of energy in which the product has not yet obtained temperature greater than 12º C in the freezer).  Accumulate 7 hours and 40 minutes, During continuous operation of the refrigerator.
Attention: Pre-cooling is the automatic operation of the compressor and the motor fan continuously for 20 minutes before defrosting be activated, super cooling the freezer to compensate for the heat generated during the thaw.
Compensation in case of lack of energy
In case of lack of energy, the product will behave according to the cases below, when the return of the Energy.
 De-icing sensor registering a temperature equal to or greater than 12ºC
 Thaw sensor registering temperature below 12ºC  The product will preserve the same regulation defined before the lack of energy. The thaw will be proceeded.
Testing Procedures
How to know if the plate is being energized
With the digital Tester measure the alternating voltage 220V between the points:
A - connector 70, on the pivots: 1 (brown) and 3 (blue)
Operation of compressor and fan motor
The electronic board connects the compressor and fan motor 5 seconds after the product has been connected to the plug. Check if there is alternating voltage 220V between the points:
B - connector 71, in the pivots: 1 (light blue) and 5 (black).
OBS: the motor-fan and the compressor operate simultaneously. The motor-fan is disconnected by the Door switch when opening any one of the doors.
Operation of the Lamps
The plate makes a direct connection between the power supply and the door switch, therefore, there is always alternating voltage 220V between points:
C - Connector 71, on the pivots: 1 (blue-light) and pivot 7 (brown).
When opening the door, with tension in these points, the corresponding lamp will light up.
Operation of the Resistances verified by the board
To verify if the resistances are being fed, measure the alternating voltage with the digital multimeter 220V in points:
D - connector 71, on the pivots: 1 (light blue) and pivot 3 (red).
Obs: - To carry out this test, the product must be in defrost, or in the forced de-icing function (sensor thaw in temperature lower than -5ºC).
How to measure the Resistances by the Plate
Unplug the product from the socket. Measure the resistance in the points with the digital multimeter:
E - connector 71 on the pivots: 1 (light blue) and 3 (red).
[Attention: for the verification of the resistances, you must disassemble the freezer compartment to measure directly the value of the resistors disconnecting their connectors, to prevent the parallel of the two may influence the outcome of the measures.]
How to Measure the Signal of the Sensors
With the Tester measure the DC voltage between the points:
F - connector 50, on pivots: 8 (white) and 9 (gray) - defrost sensor
G - connector 50, on pivots: 8 (white) and 10 (light blue) - temperature sensor.
Accompany the ohmic resistance and tension in the table on page 15 as a function of the temperature in the sensor.
Ex: for the temperature of 25ºC the ohmic resistance is 5000.00Ω and the voltage is 1.666V in current keep going.
Electrical Diagram (127V / 60Hz) (220V / 60Hz)

Electrical Diagram
Emergency Operation
When a sensor fails with the product functioning, the board has a security system, working the compressor and fan for 25 minutes and disconnecting them for 35 minutes continuously.
In this case, the high temperature indicator in the freezer (red) remains off - turning on, informing that the product has a fault, even if it is always working in this cycle of 25 minutes
connected and 35 minutes disconnected.
If the product is not connected to the socket or there is a lack of electrical power, the compressor and the Fan motor will be disconnected and will not reconnect. In this case, it will stay on / off in the control box or minimum temperature indicator (fault in the temperature sensor) or the indicator of medium temperature (fault in the defrost sensor).
Quick Freeze Function
By pressing the quick freeze button on the control panel, the compressor and the motor fan will work continuously for 2 hours and 30 minutes, or until the function is deactivated (via the button).  After the end of this function, the quick freeze indicator on the control panel turns off and the Temperature is controlled according to the regulation of the product.
When the fast freeze function is activated, the operating time of the compressor for De-icing is accumulated, even if this function is deactivated before its completion.
During the fast freeze function, the thaw (when the 7 hours and 40 minutes of compressor operation) is postponed. After the end of the fast freeze function the thaw then will be realized.
With the activation of the fast freeze function at the moment when the thaw is being performed, the indicator of this function will instantly light on the panel but the mechanical function will only will start after the thawing term.
Self-diagnosis function
When the refrigerator is plugged into the socket, the self-diagnosis function is activated by the main board for 2 seconds.
fixed on the back of the product.
If there is no fault in the sensors, after the self-diagnosis, the device starts operating  normal.
If the self-diagnosis finds a fault, it must be corrected. After the refrigerator should be reconnected, starting another self-diagnosis.
Characteristics of the Main Board
The main board receives the information generated by the sensors and controls the operation of the product to through relay actuation: one for the compressor and motor-fan; another for the resistances (from thaw and for the gutter). The board has a transformer to reduce the network voltage to 12V, and also diodes to transform the alternating current to continuous.
Also on this plate it is possible to test all the main elements of the electrical circuit: the sensors, the de-icing resistors, the fan, the operation of the door-opening lamps.
 Test Procedures by the Main Board.
Forced start function:
Pressing the test button on the main board once the compressor goes into operation immediately. A sound signal is activated by turning on the maximum temperature indicator. In this condition, the compressor works for 24 continuous hours, always with sound indicator.
Forced Defrosting
Product with temperature equal to or greater than -5 ° C (registered in the de-icing sensor)
Pressing the test button on the plate once, the compressor starts working immediately.  Pressing the test button one more time (2nd drive), the compressor is disconnected and in this one situation the defrost resistance will not be activated because the sensor indicates high temperature in the freezer, and the reading made by the board is of a voltage less than 3.076V in the defrost sensor. The product will then be 10 minutes on pause (compressor disconnected) and then afterwards it will enter normal functioning.

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