Compressor Preheating; Electronic Expansion Valve Control; Prevention To Restart For 3 Minutes (3 Minutes St); 4-Way Valve Control - Fujitsu AMUG30LMAS Service Manual

6-4. Compressor preheating

By preheating the compressor, warm airflow is quickly discharged when the operation is started.
• Triggering condition 1
– Outdoor temperature ≤ 68°F (20°C)
When outdoor temperature reaches 78.8°F (26°C), compressor preheating stops.
– 30 minutes after compressor stopped
• Triggering condition 2

6-5. 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).

6-6. Prevention to restart for 3 minutes (3 minutes st)

When the compressor fails to start for the number of times below, it does not enter operation status
for 3 minutes.
Retry number
Retry set number
When the compressor fails to start in the retry set number above, the compressor is stopped.

6-7. 4-way valve control

• If heating mode is selected at the compressor start, 4-way valve is energized for heating.
• When the air conditioner is switched between cooling and heating mode, compressor is stopped,
and the 4-way valve is switched when the 3 minutes passes and the compressor is started.
6-4. Compressor preheating
Tn
Off
32.0°F
(0°C)
On
Tn: Outdoor unit heat exchanger temp.
- (04-21) -
Tn
35.6°F
(2°C)
Pulse range
Between 47 and 480 pulses
Between 39 and 480 pulses
10
3
6. Various control