Daikin Outdoor Unit SkyAir System Classic Heat Pump RZQSG71L3V1B

Caution: Removing electrical components

Remove the cover screws before removing an electrical component

Replace the grease on the heat sink with new grease

Remove fixation screw A (2 screws)

Lift and pull the cover in the direction of the arrow

Pull the refrigerant pipe forward

Remove fixation screw B (4 screws)

Caution: Do not touch the hatched area. Always replace the grease after removing an electrical component.

Warning: Do not touch the charged area (high voltage) for 10 minutes after turning the power supply off.

If you must touch such an area, make sure that the power supply voltage of power transistor is 50 V or less.

Did you disconnect the connector of the outdoor unit fan motor?

Before measuring the continuity, disconnect the connection between compressor and power transistor.

Did you disconnect the connection between compressor and power transistor?

Measure the continuity in the following procedure.

Is there continuity in the power transistor (on inverter PCB)?

Note: If there is continuity, the resistance should be the same as each phase.

If a digital tester is used for the measurement of continuity, ∞ and continuity may be reversed.

As criteria for judging whether refrigerant is inadequate or not, refer to the following operating conditions.

<Diagnosis of inadequate refrigerant>

(1) As suction superheat degree increases due to refrigerant shortage, the electronic expansion valve tends to open (opens fully) in order to avoid overheat operation.

(2) In response to decreased evaporator capacity caused by refrigerant shortage, capacity is controlled in the inverter in order to maintain low pressure, which results in a decrease in frequency.

(3) Because of (1) and (2) above, the compressor frequency decreases despite a large difference (large load) between temperature set by the remote controller and indoor suction temperature, resulting that cooling capacity becomes unavailable.

(4) If refrigerant shortage worsens, the electronic expansion valve remains fully open and suction superheat degree further increases. In addition, because the compressor frequency drops to the level of the lowest frequency (52 Hz) and the refrigerant flow rate decrease, low pressure cannot be maintained.

<Diagnosis of inadequate refrigerant>

Warning: This procedure requires trained personnel!

Thermistor disconnected from the PCB

Temperature reading from the thermistor

Resistor value reading from the thermistor

Do the measured values correspond with the values in the table?

Sign off on the thermistor check

As criteria for judging whether refrigerant is excessively charged or not, refer to the following operating conditions.

<Diagnosis of excessive refrigerant charging>

(1) Because high pressure rises due to excessive charging, overload control is carried out and capacity tends to run short.

(2) Considering pressure load, compressor discharge pipe temperature is low.

(3) Subcooled degree of condensate liquid becomes large. Therefore, temperature of blown air passing through subcooled part decreases in heating operation.;