Recommend to use 
The duct installation work should be finished before the fitment of ceiling.
The duct must be heat insulated.
The specific 
The surface should leave a checking meatus for checking and maintenance.
Do not use air in duct and take the ceiling inner side instead. The result is because of the irregular outer air mass, strong wind and sunshine, the humidity is increased.
There may be water drop on the outside of duct. For cement and other new constructions, even if not taking ceiling inner side as duct, the humidity will also be so high. At this time, use glass fiber to perform heat preservation to the whole. (use iron net to bind the glass fiber)
Maybe exceeding the unit operation limit (for example: when indoor dry bulb temperature is 35 C, wet bulb temperature 24 C), it may lead to overload of compressor.
Affected by the capacity of air discharging fan, the strong wind in the outer duct and wind direction, when unit air sending volume exceeds the limit, the discharged water of heat exchanger will overflow, leading to water leakage.
The outdoor unit has been charged with refrigerant.
When connect the pipe to the unit or dismantling the pipe from the unit, please follow the figure shown, use spanner and torque spanner together.
When connect cone nut, the inner side and outside of cone nut should paste with refrigerant oil. Use hand to twist 
Referring to Table I to confirm the fasten torque. (too tight may damage nut leading to leakage)
Check if the connection pipe leaks, then do heat insulation treatment, as below figure shown. 
Only use seal cushion to bind the joint part of air pipe and heat insulation parts.
AU84NATEAA, AD842AHEAA specifications
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