Compressor Preheating; External Electrical Heater Control; Electronic Expansion Valve Control - Fujitsu ADUH09LUAS1 Service Manual

6-5. Compressor preheating

By preheating the compressor, warm airflow is quickly discharged when the operation is started.
• Triggering condition
– 30 minutes after compressor stopped.
– Outdoor unit heat exchanger temperature (Tn)
→hen the jumper wire (JM2) is disconnected:

6-6. External electrical heater control

The external electrical heater is operated as below.
Ts -5.4°F
(Ts -3°C)
Ts -21.6°F
(Ts -12°C)
NOTES:
• →hen the compressor stop, external electric heater is off.
• It operates only in heating mode and when the indoor fan operates. (However, S-LO→ is exclud-
ed.)

6-7. Electronic expansion valve control

The most proper opening of the electronic expansion valve is calculated and controlled under the
present operating condition based on the table below.
Operation mode
Cooling/dry mode
Heating mode
NOTE: At the time of supplying the power to the outdoor unit, the initialization of the electronic ex-
pansion valve is operated (528 pulses are input to the closing direction).
6-5. Compressor preheating
24.8°F
(-4°C)
41.0°F
(5°C)
Heater : Off
Heater : On
Heater : Off
When the room
temperature drops
Tn
Tn
Off
28.4°F
(-2°C)
On
Tn
Tn
Off
44.6°F
(7°C)
On
When the room
temperature rises
Ts -1.8°F
(Ts -1°C)
Ts -18.0°F
(Ts -10°C)
Between 52 and 480 pulses
- (04-24) -
Ts: Setting temperature
Pulse range
6. Various control