Panasonic WH-MHF09G3E8, Service Manual, Page: 77 / 140

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13.1.6 Low Frequency Protection Control 2

When all the below conditions comply, the minimum compressor frequency will change to lower frequency.
Temperature, T, for: Heating
Outlet water (°C) T < 14 or T ≥ 48
Outdoor air (°C) T < 4 or T ≥ 24
Indoor heat exchanger (°C) T ≥ 0
13.1.7 High Pressure Sensor Control

Purpose:
- To protect the system operation.

Detection period:
- After compressor on for 1 minute.

Detection conditions:
- When abnormal high voltage detection, 5 V or when open circuit detection 0V for 5 seconds continuously.

After detection:
- When abnormality is detected 4 times within 120 minutes, unit stop operation.
- OFF/ON control panel LED will blink (H64 error occurs).
13.1.8 Outside Temperature Current Control
23°C
21°C
14°C
12°C
-25°C
-28°C
Compressor stop
Outdoor temperature
Max.
current
value is
regulated
13.1.9 Crank Case Heater Control

Purpose:
- For compressor protection during low outdoor ambient operation (during heating low temperature operation).

Control content:
a. Trigger heater START condition
o
When the outdoor air temperature is below than 5°C, and discharge temperature is 11°C or below.
b. Resetting heater STOP condition
1.
When the outdoor air temperature exceeds entry condition (2°C)
2.
When the discharge temperature exceeds entry condition (5°C)