Sharp SPLIT TYPE ROOM AIR CONDITIONERS AY-XP07ER – electronic circuit diagram and functions.

INDOOR UNIT
AY-XP07ER
AY-XP09ER
AY-XP12ER
OUTDOOR UNIT
AE-X07ER
AE-X09ER
SX435AYXP07ER
Functions 
Startup control

The main relay remains off during the first 45 seconds (first safety time) immediately after the power cord is plugged into an AC outlet in order to disable outdoor unit operation and protect outdoor unit electric components.

Restart control

Once the compressor stops operating, it will not restart for 180 seconds to protect the compressor.  Therefore, if the operating compressor is shut down from the remote control and then turned back on immediately after, the compressor will restart after a preset delay time.  (The indoor unit will restart operation immediately after the ON switch is operated on the remote control.)

Cold air prevention control

When the air conditioner starts up in heating mode, the indoor unit fan will not operate until the temperature of the indoor unit heat exchanger reaches about 23ºC in order to prevent cold air from blowing into the room.

Also, the indoor unit fan operates at low speed until the temperature of the indoor unit heat exchanger reaches about 38ºC so that people in the room will not feel chilly air flow.

Odor prevention control

When the air conditioner starts up in cooling mode, the discharged air temperature is lowered slightly, and for the reduction of unpleasant odors the operation of the indoor unit fan is delayed 60 seconds if the automatic fan speed mode in cooling mode is set.

Electronic Control Circuit Diagram

Indoor unit heat exchanger freeze prevention control
If the temperature of the indoor unit heat exchanger remains below 0ºC for 4 consecutive minutes during cooling or dehumidifying operation, the compressor operation stops temporarily in order to prevent freezing.  When the temperature of the indoor unit heat exchanger rises to 2ºC or higher after about 180 seconds, the compressor restarts and resumes normal operation.

Outdoor unit 2-way valve freeze prevention control
If the temperature of the outdoor unit 2-way valve remains below 0ºC for 10 consecutive minutes during cooling or dehumidifying operation, the compressor operation stops temporarily in order to prevent freezing.  When the temperature of the 2-way valve rises to 10ºC or higher after about 180 seconds, the compressor restarts and resumes normal operation.

Indoor unit overheat prevention control
During heating operation, if the temperature of the indoor unit heat
exchanger exceeds the indoor unit heat exchanger overheat prevention temperature (about 45 to 54ºC) which is determined by the operating frequency and operating status, the operating frequency is decreased by about 4 to 15 Hz. Then, this operation is repeated every 60 seconds until the temperature of the indoor unit heat exchanger drops below the overheat protection temperature.  Once the temperature of the indoor unit heat exchanger drops below the overheat protection temperature, the operating frequency is increased by about 4 to 10 Hz every 60 seconds until the normal operation condition resumes.  If the temperature of the indoor unit heat exchanger exceeds the overheat protection temperature for 60 seconds at minimum operating frequency, the compressor stops operating and then restarts after about 180 seconds, and the above mentioned control is repeated.

Outdoor unit overheat prevention control
During cooling operation, if the temperature of the outdoor unit heat
exchanger exceeds the outdoor unit heat exchanger overheat prevention temperature (about 55ºC), the operating frequency is decreased by about 4 to 15 Hz. Then, this operation is repeated every 60 seconds until the temperature of the outdoor unit heat exchanger drops to about 54ºC or lower.
Once the temperature of the outdoor unit heat exchanger drops to about 54ºC or lower, the operating frequency is increased by about 4 to 10 Hz every 60 seconds until the normal operation condition resumes.
If the temperature of the outdoor unit heat exchanger exceeds the outdoor unit heat exchanger overheat protection temperature for 120 seconds at minimum operating frequency, the compressor stops operating and then restarts after about 180 seconds, and the abovementioned control is repeated.

Compressor overheat prevention control
If the temperature of the compressor exceeds the compressor overheat prevention temperature (110ºC), the operation frequency is decreased by about 4 to 10 Hz. Then, this operation is repeated every 60 seconds until the temperature of the compressor drops below the overheat protection temperature (100ºC).  Once the temperature of the compressor drops below the overheat protection temperature, the operating frequency is increased by about 4 to 10 Hz every 60 seconds until the normal operation condition resumes.  If the temperature of the compressor exceeds the overheat protection temperature (for 120 seconds in cooling operation or 60 seconds in heating operation) at minimum operating frequency, the compressor stops operating and then restarts after about 180 seconds, and the above mentioned control is repeated.

Startup control
When the air conditioner starts in the cooling or heating mode, if the room temperature is 2ºC higher than the set temperature (in cooling operation) or 3.5ºC lower (in heating operation), the air conditioner operates with the operating frequency at maximum. Then, when the set temperature is reached, the air conditioner operates at the operating frequency determined by fuzzy logic calculation, then enters the normal control mode after a while.
Peak control
If the current flowing in the air conditioner exceeds the peak control current (see the table below), the operation frequency is decreased until the current value drops below the peak control current regardless of the frequency control demand issued from the indoor unit based on the room temperature.

Outdoor unit fan delay control

The compressor stops immediately after cooling, dehumidifying or heating operation is shut down, but the outdoor unit fan continues operation for 50 seconds before it stops.

Reverse defrosting

The defrost operation starts when the compressor operating time exceeds 20 minutes during heating operation, as shown below, and the outside air temperature and the outdoor unit heat exchanger temperature meet certain conditions. When the defrost operation starts, the indoor unit fan stops. The defrost operation stops when the outdoor unit heat exchanger temperature rises to about 13ºC or higher or the defrosting time exceeds 10 minutes.

ON timer

The ON timer can be activated by pressing the ON timer button. When the ON timer is activated, the operation start time is adjusted based on fuzzy logic calculations 1 hour before the set time so that the room temperature reaches the set temperature at the set time.

OFF timer

The OFF timer can be activated by pressing the OFF timer button.  When the OFF timer is set, the operation stops after the set time.  When this timer is set, the compressor operating frequency lowers for quieter operation, and the room temperature is gradually varied after one hour (reduced 1ºC three times (max. 3ºC) in heating, or increased 0.3ºC three times (max. 1ºC) in cooling or dehumidifying operation) so that the room temperature remains suitable for comfortable sleeping.

Power ON start

If a jumper cable is inserted in the location marked with HAJP on the indoor unit control printed circuit board (control PCB), connecting the power cord to an AC outlet starts the air conditioner in either cooling or heating mode, which is determined automatically by the room temperature sensor.  When a circuit breaker is used to control the ON/OFF operation, please insert a jumper as described above.

Self-diagnostic malfunction code display

Indoor unit

1) When a malfunction is confirmed, all relays turn off and a flashing malfunction code number is displayed to indicate the type of malfunction.

When the air conditioner is in non-operating condition, holding down AUX button for more than 5 seconds activates the malfunction code display function.

The operation continues only in the case of a serial open-circuit, and the main relay turns off after 30 seconds if the open-circuit condition remains.

In the case of a serial short-circuit, the air conditioner continues operating without a malfunction code display, and the main relay turns off after 30 seconds if the short-circuit condition remains.  The malfunction information is stored in memory, and can be

recalled later and shown on display.

2) The self-diagnostic memory can be recalled and shown on the display by stopping the operation and holding down AUX button for more than 5 seconds.

3) The content of self-diagnosis (malfunction mode) is indicated by a flashing number.

Outdoor unit

If a malfunction occurs, LED1 on the outdoor unit flashes in 0.2-second intervals

Information about auto mode

In the AUTO mode, the temperature setting and mode are automatically selected according to the room temperature and outdoor temperature when the unit is turned on.

Difference of operation in Auto and Manual modes

In the Auto mode, the temperature setting is automatically determined based on the outside air temperature. In addition, the air conditioner operation differs from the operation in the Manual mode.

Limitation on operating frequency in heating operation

If any of the following conditions is met 1 minute after operation startup, the operating frequency is decreased to 90% in order to reduce the operating sound and save energy in exchange for room warming speed.

1) First operation after power ON

2) Outside air temperature is 3ºC or higher

3) Room temperature is 10ºC or higher, or difference between set temperature and room temperature is 15ºC or less

4) Current time is between 20:00 and 7:00

Note that the limitation is effective only for 60 minutes after operation startup.

Dehumidifying operation control

If the room temperature is 26ºC or higher when dehumidifying operation starts, the dehumidifying operation provides a low cooling effect in accordance with the room temperature setting automatically determined based on the outside air operation. (The setting value is the same as the set temperature for cooling operation in the auto mode.)  If the room temperature is lower than 26ºC when dehumidifying operation starts, the dehumidifying operation minimizes the lowering of the room temperature.

Self Clean operation

Heating or Fan operation and Cluster operation are performed simultaneously.  The judgment of whether Heating or Fan operation is used is based on the outside air temperature at 3 minutes after the start of internal cleaning.

The operation stops after 40 minutes. (The air conditioner shows the remaining minutes: 40 → 39 → 38 ... 3 → 2 → 1)

Plasmacluster Ion function

Operating the Plasmacluster Ion button while the air conditioner is in operation or in non-operation allows the switching of the operation mode in the following sequence: “Air Clean operation” → “Ion Balance operation” → “Stop”.

• “Self Clean operation” generates about equal amounts of (+)ions and (-)ions from the cluster unit to provide clean air.

• “Ion Blance operation” generates more (-)ions than (+)ions from the cluster unit.

If the Plasmacluster Ion generation function is operated together with the air conditioner operation, the indoor unit fan speed and louver direction are in accordance with the air conditioner settings.  If the Plasmacluster Ion generation function is used without operating

the air conditioning function, the indoor unit fan operates at a very low speed and the upper louver is angled upward and the lower louver remains horizontal. (The airflow volume and direction can be changed by using the remote control.)

Hot keep

When the room temperature rises above the set temperature by 0.6ºC or more, the ON/OFF operation of the compressor and indoor unit fan is controlled in order to lower the room temperature.  (The values indicated below, such as "0.6ºC" and "1.3ºC," vary depending on the outside air temperature.)

Hot keep zone 1
With the compressor frequency at the lowest, if the room temperature is higher than the set temperature by 0.6ºC but no more than 1.3ºC, the following processes will be activated.
1) The compressor stops temporarily, and restarts after 2 minutes.
2) If the room temperature remains in the hot keep zone, the compressor is turned OFF and ON in 3-minute intervals.
3) The indoor unit fan turns OFF and ON with a delay of 30 seconds from the compressor OFF/ON.
4) After the above operation in 3-minute intervals is repeated four times, the interval extends to 6 minutes.
Hot keep zone 2
If the compressor ON/OFF in hot keep zone 1 fails to bring the room temperature within 1.3ºC above the set temperature, the following processes will be activated.
1) The compressor repeats a cycle of 8-minute OFF and 6-minute  ON.
2) After the second time, the compressor remains completely OFF and only the indoor unit fan repeats OFF-ON in set intervals.
3) While the compressor is completely OFF in 2), the louvers are set horizontally to prevent cold air from blowing.
The zone transition and the end of hot keep operation (room temperature lower than the set temperature) are judged when the compressor ON period ends.
* This function cannot be repealed.

Winter cool

The air conditioner cannot be operated in the cooling mode during winter (low outside air temperature) in principle. However, by cutting the JP-WK (jumper wire) on the outdoor unit control printed circuit board (control PCB), cooling operation can be operated at a lower outside air temperature. When the outside air temperature is low, the outdoor unit fan operates at slower speed.

Auto restart

When power failure occurs, after power is recovered, the unit will automatically restart in the same setting which were active before the power failure.

Operating mode (Cool, Heat, Dry)

Temperature adjustment (within 2ºC range) automatic operation

Temperature setting

Fan setting

Air flow direction

Power ON/OFF

Automatic operation mode setting

Swing louvre

Plasmacluster mode

Setting not memorized

Timer setting

Full power setting

Internal cleaning

Disabling auto restart function

By removing (cutting) jumper J (JPJ) on the printed circuit board (PCB), the auto restart function can be disabled.

Explanation of cluster circuit

The cluster unit generates cluster ions, which are circulated throughout the room by the air flow created by the blower fan (indoor unit fan motor) in the air conditioner unit.

1) When microcomputer output 1 turns "H," the IC6-1 output changes to "Lo," turning ON the SSR and applying 230 V to the cluster unit for the generation of cluster ions (positive and negative ions).

2) When the SSR is ON, monitor voltage (1 to 3.5 V) is applied to the microcomputer input. the monitor voltage is lower than 0.1 V or higher than 4.5 V for 30 consecutive minutes, an error is detected and the cluster drive output (SSR) remains OFF until the operation is shut down.

Note that the above condition will not cause the air conditioner to shut down in an error mode, and the air conditioning operation continues.

3) For a cluster mode change, microcomputer output 2 changes to "H," and this sets the IC6-2 output to "Lo" and turns ON the Q8 (digital transistor).  As a result, the relay inside the cluster unit is applied with 12 V, and the internal relay turns ON. When the SSR is turned ON in this condition, more negative ions are generated to provide negative-ion-rich air.

* Cluster mode switching is usually performed in the cluster OFF (SSR = OFF) status.

PAM (Pulse Amplitude Modulation)
The PAM circuit varies the compressor drive voltage and controls the rotation speed of the compressor.
The IGBT shown in the block diagram charges the energy (electromotive force) generated by the reactor to the electrolytic capacitor for the inverter by turning ON and OFF.

When the IGBT is ON, an electric current flows to the IGBT via the reactor (L5) and diode bridge (DB2).
When the IGBT turns OFF, the energy stored while the IGBT was ON is charged to the voltage doubler capacitor via the diode bridge (DB1).
As such, by varying the ON/OFF duty of the IGBT, the output voltage is varied.

INDOOR UNIT [MICROCOMPUTER CONTROL SYSTEM Schematic

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