GMV5 DC INVERTER VRF UNITS SERVICE MANUAL 
105 
 
2) When unit commissioning is started, the system automatically selects an operation mode according to 
the environment temperature: 
Cooling mode when the outdoor environment temperature is higher than 20°C.  
Heating mode when the outdoor environment temperature is lower than 20°C.  
3) Before starting commissioning, make sure again that stop valves of all basic modules of the ODU 
have been completely opened. 
4)  During  commissioning,  the  front  panel  of  ODU  must  be  completely  covered.  Otherwise, 
commissioning accuracy may be affected (as shown in the following figure). 
 
5) Before commissioning, make sure that appending refrigerants to pipes has finished completely or for 
more than 70%. 
Has the compressor 
been  preheated  for 
more  than  eight 
hours?