Symbol Diagnosis Diagnosis method
H99 Indoor operating unit
freezing
The restriction on the compressor frequency is started when the indoor unit heat exchanger temperature is
between 8 °C and 12 °C. Operation stops if a temperature below 0 °C continues for 6 minutes. Three minutes
later, operation is started up at a temperature from 3 °C to 8 °C. The restriction on the compressor frequency
is released at a temperature between 13 °C and 14 °C.
<Diagnosis checkpoint>
1. A cooling or dry mode operation conducted at a low outside air temperature is mainly to blame:
this is not indicative of any malfunctioning.
If the outside air temperature rises during automatic operation in the winter months, the dry mode
operation is selected. The H99 diagnostic display also appears at such a time.
2. Check the refrigerating cycle: Gas may be leaking (the amount of refrigerant is low) or a pipe may be
broken, etc.
3. Check also for short circuits indoors and clogging of the air filters.
F11 4-way valve switching
failure
CU-2E:
When the indoor unit heat exchanger temperature is under -5 °C during a warming operation or above 45 °C
during a cooling or dry mode operation four minutes after the compressor has started up, the F11 diagnostic
symbol is stored in the memory, and operation stops. 3 minutes later, operation is restarted.This trouble
display appears when this happens on 4 occasions in a 30-minute period.
CU-3E/4E:
When a difference of 0 °C to 5 °C has been detected between the outdoor unit heat exchanger temperature
and liquid side pipe temperature on 5 occasions, the trouble display appears.
<Diagnosis checkpoint>
1. Check the 4-way valve coil: Check that no power is supplied to the coil during cooling and dry mode
operations, and that power is supplied during heating operations. Inspect the coil for broken wires (open
circuits).
2. If the coil is trouble-free, the switching action of the 4-way valve may be defective.
F17 Indoor standby units
freezing
CU-2E:
After the operation of one indoor unit stops continuously for 5 minutes. The hole operation stops when the
stopping indoor unit pipe temperature is under -5 °C continuously for 1 minute or under 0 °C continuously for
5 minutes, and operation restarts after 3 minutes. This trouble display appears if that trouble happens on 3
occasions in a 30-minute period.
CU-3E/4E:
When the difference of an intake temperature (room temperature sensor) and the indoor unit heat exchanger
temperature (piping sensor) is higher than 10 °C or an indoor unit heat exchanger temperature of below -1 °C
has been detected continuously for 5 minutes, operation stops. Three minutes later, it is started up, and the
trouble display appears when this has occurred on 3 consecutive occasions.
<Diagnosis checkpoint>
1. Check the refrigerating cycle: Expansion valve leakage
2. Check the indoor unit pipe temperature sensor (check for changes in its characteristics and check its
resistance).
F90 PFC circuit protection
(CU-2E)
CU-2E:
When the rotation of the compressor is not synchronized with the control signal, the F90 diagnostic display is
stored in the memory, and operation stops. 3 minutes later, operation is restarted. This trouble display appears
when this happens on 4 occasions in a 10-minute period.
* With the multi 53 or above, it appears when this happens on 16 occasions.
CU-3E/4E:
When a DC voltage below 305V to 328V has been detected on 16 occasions, this trouble display appears.
<Diagnosis checkpoint>
1. To check whether the 2-way or 3-way valve has been left open by mistake, operation is performed for one
to several minutes after the compressor has started up, F93 is stored in the memory as the symptom, and
operation stops.
2. Check the inverter circuit (for open circuits) in the control P.C. Board: Check the IPM base current (6
locations) within 3 minutes after the power has been turned back on. As the symptom, F93 is stored in the
memory 30 seconds after the compressor has started up, and operation stops. The trouble display
appears after 4 restarts.
3. Check for broken wires (open circuits) in the compressor winding: Approximately 1 ohm under normal
conditions for each phase (same symptom as in 2.)
4. Check the power supply voltage has been down or not.
Main circuit low
voltage
(CU-3E/4E)
F91 Refrigeration cycle
abnormality
CU-2E:
When the rotation speed of the compressor exceeds the setting frequency and the total current is 1.5A or
higher to 1.9A or lower continuously for 5 minutes, operation stops if the indoor unit heat exchanger
temperature is higher than 20 °C during cooling or dry operation or if it is under 25 °C during heating. Three
minutes later, it is restarted, and if the trouble occurs on 2 consecutive occasions in a 20-minute period, the
trouble display appears.
CU-3E/4E:
When the compressor frequency is above 55 Hz and the current drops below the prescribed level continuously
for 7 minutes, operation stops, and it is restarted 3 minutes later.
When the compressor discharge temperature has exceeded the setting and the expansion valve has remained
fully open for 80 seconds, operation stops, and it is restarted 3 minutes later.
When the stopping described above has occurred on 4 occasions, operation stops, and the trouble display
appears.
<Diagnosis checkpoint>
1. Check the refrigerating cycle: Gas may be leaking (more than one-half of the volume of the gas has gone).
The diagnostic displays resulting from a gas leak generally change in the following sequence depending
on the extent of the gas leak: H99 → F97 → F91 → H16.
The range of this trouble (F91) is limited. (Compressor protection at the start of the season)
84
CS-ME7CKPG / CS-ME10CKPG / CS-ME12CKPG / CS-ME14CKPG / CS-ME18CKPG / CU-2E15CBPG / CU-2E18CBPG / CU-3E23CBPG / CU-4E27CBPG
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