Panasonic CS-ME7DKEG Service Manual page 91

Symbol Diagnosis
H99 Indoor operating unit
freezing
F11 4-way valve switching
failure
F17 Indoor standby units
freezing
F90 PFC circuit protection When a DC voltage over 393V to 424V has been detected on 16 occasions, this trouble display appears.
F91 Refrigeration cycle
abnormality
F93 Compressor abnormal
revolution
F95 Outdoor high pressure
protection
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 outdoor 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.
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 operation. Inspect the coil for broken wires (open-
circuiting).
2. If the coil trouble-free, the switching action of the 4-way valve may be defective.
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
resiastance.)
<Diagnosis checkpoint>
1. To check whether the shutting valve has been left close 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-circuiting) 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 (for open-circuiting) 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 fluctuating or not.
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 diagnosis 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)
When a state in which the rotation of the compressor is not synchronized with the control signal has been
detected on 8 successive occasions, operation stops, and the trouble display appears.
<Diagnosis checkpoint>
1. To check whether the shutting valve has been left close 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-circuiting) 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-circuiting) in the compressor winding: Approximately 1 ohm under normal
conditions for each phase (same symptom as in 2.)
CU-2E only
When the temperature of the outdoor unit heat exchanger temperature sensor exceeds 62°C, the F95 diagnostic
symbol is stored in the memory, and operation stops. Thirteen minutes later, operation is restarted at a
temperature below 48°C. This trouble display appears when this happens on 4 occasions in a 20-minute period.
<Diagnosis checkpoint>
1. Check the indoor unit pipe temperature sensor. (Check for changes in its characteristics and check its
resiastance.)
2. Check whether something is interfering with the dissipation of the heat outdoors.
CS-ME7DKEG CS-ME10DD3EG / CS-ME10DTEG CS-E15DB4EW
Diagnosis method
91