Air Conditioner Service Manual
55
3.2.16 F4---Cooling system Gas flow abnormal protection
When compressor startup, unit will check the variation of IDU coil temperature. If there is mistake installer forgetting
to open the 2-way or 3-way valve on ODU, the gas can’t flow in the cooling system, it will show F4 protection.
Check the 2-way
valve and 3-way
valve opened?
The IPT sensor
open or short?