If you see an error message showing “999″ and “000″ when you are enjoying comfortable fresh air with Holtop floor standing type fresh air heat recovery ventilation system, please do not worry! This means that the high-sensitivity sensor needs to be cleaned.
The HOLTOP fresh air system is equipped with highly sensitive air quality sensors, which can detect small particles quickly and accurately to monitor indoor air quality in real time, and adjust the air supply and exhaust ratio through software to ensure clean and comfortable indoor air.
Due to the long-term operation of the fresh air system, the accumulation of small particles at the sensor detection position will cause inaccurate monitoring data. In this case, the operation interface displays “999″ and “000″, indicating that the sensor needs to be cleaned.
Cleanup steps Notice: cut off the power before cleaning. ■ Step Open the cabinet door, find the position of the electric control box in the upper right corner, and pull out the electric control box about 20cm ■ Cleaning Method 1 Use a Dust Blower Use the dust blower to aim at the air inlet of the sensor, quickly squeeze the blower about 5 times to blow off the internal dust, restore the equipment and turn on the power for normal use. ■ Cleaning Method 2 Use a Household Hair Dryer Use a blower to aim at the air inlet of the sensor, turn on the cold air mode for cleaning, restore the equipment and turn on the power supply for normal use. 
The above two methods can solve the sensor problem. It is recommended to clean up regularly to maintain the sensitivity of the sensor. Use and maintain the fresh air system correctly, replace the filter regularly, and always enjoy the clean and comfortable home environment brought by Holtop fresh air products. 
