Heat Controller B-MMH09FA-1 Manuel D’Utilisation

Service Manual

• Compressor step varies considering conditions such as room temperature, operating room number,  

temperature gap between room temperature and set point temperature and so on.

• The linear expansion valve is pulse is modulated to keep constant superheat or subcooling.

• Outdoor fan operates at High or Off to respond to the load condition.

• Reversing valves is used to change cooling to heating, heating to cooling.

• After 45 minutes in heating mode, defrost mode will take effect if the outdoor pipe temp is below 5

°C 

(23

°F). The defrost mode will end when the outdoor pipe temp is above 12°C (53.6°F) or after the unit 

has been operated in cooling mode for 9 minutes.

• To de-ice the outdoor heat exchanger in low temperature conditions, the unit will defrost by changing 

the operating mode from heating to cooling, while turning off both indoor and outdoor fans. 

• In single(one) compressor operation duration, another compressor will operate for 30 seconds every 1 

hours.

• To protect compressor from being overloaded, the compressor overload protector will turn the 

compressor off.

• If the refrigerant cycle's pressure is too high, above 36.7 kgf/cm

2

 (521.997psi), the high pressure 

switch will turn the compressor off.