![background image](http://html1.mh-extra.com/html/daikin/fhq100buv1b-x-2/fhq100buv1b-x-2_service-manual_2459261247.webp)
Troubleshooting by Remote Controller Display / LED Display
SiBE28-804
236
Troubleshooting
Check for Inadequate Refrigerant
As criteria for judging whether refrigerant is inadequate or not, refer to the following operating
conditions.
<Diagnosis of inadequate refrigerant>
In cooling operation
(1) As suction superheat degree increases due to gas 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 gas 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 gas 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.
Check No.13
Cooling
High pressure
(Pressure sensor)
Low pressure
(Pressure sensor)
Suction superheat degree
Compressor frequency
Electronic expansion valve
Adequate level
Gas shortage warning
As compressor frequency
decreases, high pressure
decreases.
(Maintains a certain level
of low pressure)
Abnormal gas shortage
Actual high pressure
When the refrigerant flow rate
decrease, it is impossible to
maintain a low pressure.
As the electronic expansion valve
opening degree reaches the maximum,
suction superheat degree increases.
Reaches the lowest frequency
Inadequate
In response to decreased evaporator capacity
caused by gas shortage, capacity is controlled in
the inverter in order to maintain a low pressure,
which resulting in a decrease in frequency.
The maximum opening degree of the
electronic expansion valve (480 pulses)
Avoid overheat operation by
changing SH target value
(Degree of inadequate refrigerant)
Summary of Contents for FHQ100BUV1B x 2
Page 13: ...SiBE28 804 2 ...
Page 19: ...Model Name and Power Supply SiBE28 804 8 General Information ...
Page 29: ...Specifications SiBE28 804 18 Specifications ...
Page 33: ...Wired Remote Controller SiBE28 804 22 Remote Controller 1 2 Installation ...
Page 34: ...SiBE28 804 Wired Remote Controller Remote Controller 23 ...
Page 93: ...Outdoor Unit Fan Speed Control SiBE28 804 82 Functional Description ...
Page 131: ...Test Run and Operation Data SiBE28 804 120 Test Operation ...
Page 251: ...Troubleshooting by Remote Controller Display LED Display SiBE28 804 240 Troubleshooting ...
Page 277: ...PCB Layout SiBE28 804 266 Appendix ...
Page 297: ...RZQ100 140C7 RZQS125 140C7V1B SiBE28 804 286 Removal Procedure ...
Page 311: ...SiBE28 804 iv Index ...