First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 
In case CN721 is not connected or R.V. coil is open, voltage is generated between the terminal pins of the connector although any signal is not being transmitted to R.V. coil.
and 
on the inverter P.C. board 3 minutes after the power supply is turned ON?
and 
on the inverter P.C. board 3 minutes after the power supply is turned ON?
MUZ-FD09NA specifications
The Mitsubishi Electronics MUZ-FD09NA is a highly efficient and versatile air conditioning unit designed for both residential and light commercial applications. This model is part of Mitsubishi's advanced range of split-system air conditioners which emphasize energy efficiency, comfort, and innovative technology.One of the standout features of the MUZ-FD09NA is its energy efficiency. The unit boasts an impressive SEER (Seasonal Energy Efficiency Ratio) rating, which translates to reduced energy consumption and lower utility bills. This makes it an eco-friendly option for users looking to minimize their carbon footprint while enjoying comfortable indoor climates year-round.
The MUZ-FD09NA utilizes advanced inverter technology, which enables the compressor to adjust its speed based on the cooling or heating demand. This not only enhances comfort by maintaining a steady temperature but also significantly reduces energy consumption compared to traditional fixed-speed systems. Additionally, the inverter technology allows for quieter operation, making it ideal for use in bedrooms or study areas where noise can be disruptive.
For air purification, the MUZ-FD09NA is equipped with a high-efficiency filtration system that removes dust, allergens, and other particles from the air. This feature is especially beneficial for individuals with allergies or respiratory issues, ensuring cleaner and healthier indoor air quality.
In terms of user convenience, the unit comes with a user-friendly remote control, allowing for easy adjustment of settings from a distance. Some models may also offer Wi-Fi capability, enabling users to control their air conditioning unit through a smart device, even when away from home.
The MUZ-FD09NA is designed to operate in a wide range of temperatures, making it suitable for various climates. It can effectively provide cooling in the summer and heating in the winter, ensuring comfort throughout the year.
Furthermore, the unit features a compact and sleek design, allowing for easy installation in a variety of spaces without compromising aesthetics.
Overall, the Mitsubishi Electronics MUZ-FD09NA combines energy efficiency, advanced technology, and user-friendly features, making it a reliable choice for maintaining a comfortable indoor environment. Whether for residential or light commercial use, this air conditioning unit stands out as an effective solution for climate control needs.