Air To Air Heat Pump Operation In Thermistor Error - IVT 09LR-N Service Manual

Function
29 PAM clock error When power source frequency can-
not be determined (at startup), or
when power source clock cannot
be detected for 1 continuous sec-
ond (at startup).
✩1—The outdoor unit restarts four times before the indoor unit error is displayed (complete shutdown).
✩2—A single error judgment results in the display of the indoor unit error (complete shutdown).
✩3—The outdoor unit restarts eight times before the indoor unit error is displayed (complete shutdown).

[2] AIR TO AIR HEAT PUMP OPERATION IN THERMISTOR ERROR

1. Indoor unit
Item Mode
Room temperature Auto
thermistor (TH1)
Cooling
Dehumidifying
Heating
Heat exchanger Cooling
thermistor (TH2) Dehumidifying
Heating
Operation
Description Detection period
At compressor startup,
when in operation
Control operation When resistance
is low (tempera-
ture judged higher
than actual)
Operation mode Cooling mode is
judgment activated even if
room temperature
is low.
Frequency control Room becomes too
cold.
Room temperature Normal operation.
memory
Frequency control
Frequency control Room does not
become warm.
Freeze prevention Indoor unit evapo-
rator may freeze.
Cold air prevention Cold air prevention
deactivates too
soon and cold air
discharges.
Reset condition
Compressor continues
operation without stop-
ping.
Short-circuit
Cooling mode is Heating mode is
activated in most activated even if
cases. room temperature
is high.
Air conditioner Room does not
operates in full become cool.
power even when
set temperature is
reached.
Room temperature Normal operation.
is stored in memory
as 31.0C, and
compressor does
not stop.
Hot keep status Room becomes too
results immedi- warm.
ately after opera-
tion starts.
Frequency does
not increase above
30 Hz (40 Hz).
Indoor unit evapo- Compressor stops
rator may freeze. occasionally.
Compressor oper- Cold air prevention
ates at low speed deactivates too
or stops, and fre- slow.
quency does not
increase.
3 – 3
Self-diagnosis result
display
Indoor Indoor
unit error unit
display
None Yes
When resistance Open-circuit
is high (tempera-
ture judged lower
than actual)
Heating mode is
always activated.
Compressor does
not operate.
Room temperature
is stored in memory
as 18.5C, and
compressor does
not operate.
Air conditioner
operates in full
power even when
set temperature is
reached.
Compressor does
not operate.
Cold air prevention
does not deacti-
vate, and indoor
unit fan does not
rotate.
12LRN
Outdoor
unit
Yes