Sinclair SDV5 Series Service Manual page 55

 TL temperature sensor damaged.
 TL temperature sensor connect to the main control board is loose.
 Main PCB damaged.
2.12.5 Procedure
T4 sensor detected temperature is lower
T4 temperature sensor has
short-circuited or failed
Replace outdoor main control board
2.13 F1: DC bus voltage protection (Only for 100~160 model)
2.13.1 Digital display output
F1
2.13.2 Description
 F1 indicates DC bus voltage protection.
 The system stops running.
 Error code is displayed on the outdoor unit PCB.
2.13.3 Trigger / recover condition
 Trigger condition: If IC55 main chip couldn't receive the DC
in the first 5 seconds period when power on, it would report F1 and the big relay is forbid to close
 Recover condition: IC55 main chip can receive the DC
 Reset method: Resume automatically.
2.13.4 Possible causes
 DC fan motor damaged.
 The wire connect CN52 with CN53 is loose (100/120 model can ignore this reason for there's not this wire
connection).
 Main control board damaged.
 Filter board damaged (100/120 model can ignore this reason for they don't have a filter board).
54
EP
than -5℃
No
No
Yes
Temperature over operation range
Yes
Replace the T4 sensor
generatrix voltage detection signal or the voltage less than 200VDC
generatrix voltage detection signal and the voltage over 200VDC
.
.