Carrier 38QUA009DS, Service Manual, Page: 82 / 116

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15. Electronic Function
15.1 Abbreviation
T1: Indoor room temperature
T2: Coil temperature of indoor heat exchanger
middle.
T2B: Coil temperature of indoor heat exchanger
outlet.
T3: Coil temperature of condenser
T4: Outdoor ambient temperature
T5: Compressor discharge temperature
Td: Target temperature
15.2 Display function
15.2.1 Icon explanation on indoor display board
(A5 Duct)
15.2.2 Icon explanation on indoor display board
(Compact cassette).
15.2.3 Icon explanation on indoor display board
(slim Cassette).
15.2.1 Icon explanation on indoor display board
(Ceiling Floor)
15.3 Main Protection
15.3.1 Three minutes delay at restart for
compressor
1 minute delay for the 1
st
time stand-up and 3
minutes delay for others.
15.3.2 Temperature protection of
compressor top
The unit will stop working when the compressor
top temp. protector cut off, and will restart after
the compressor top temp. protector restart.
15.3.3 Temperature protection of
compressor discharge
When the compressor discharge temp. is
getting higher, the running frequency will be
limited as below rules:
---Compressor discharge temp. T5>115
℃
(239°F) for 5s, compressor stops and restarts
up till T5<90
℃
(194°F)
---110<T5<115
℃
(239°F), decrease the
frequency to the lower level every 2 minutes.
---105(221°F)<T5<110
℃
(230°F), keep running
at the current frequency.
----T5<105
℃
(221°F), no limit for frequency.
15.3.4 Fan speed malfunction
When indoor fan speed keeps too low (lower
than 300RPM) for 50s, the indoor fan will shut
off and restart 30s later, if protection happened
3 times when fan motor restarts continuously,
the unit will stop and the LED will display the
failure.
When outdoor fan speed keeps too low (lower
than 100RPM) or too high (higher than
1500RPM) for 60s, the unit will stop and the
LED will display the failure. Malfunction is
cleared 30s later.
OPERATION TIMER DEF./FAN ALARM
Temporary button
Operation lamp
Timer indicator
Infrared signal receiver
Alarm indicator
PRE-DEF indicator(cooling and heating type)
or fan only indicator(cooling only type)
MANUAL
Display digital tube