- 101 -
Check (TB3) voltage of indoor/outdoor unit
transmission terminal board on outdoor unit.
DC24~30V
YES
NO
Disconnect transmission line from TB3 and
check voltage of TB3
DC24~30V
YES
NO
Check voltage between CNVCC3 1-3 on the main board
DC24~30V
YES
NO
Check voltage between CNVCC2 1-3 on the inverter board
DC24~30V
YES
NO
Check voltage between CNVDC 1-4 on the inverter board
DC500~640V
YES
NO
Check the voltage of power-supply terminal board
TB1 on the outdoor/heat-source units
DC360~457V
NO
NO
Check loose connectors on the controller board of
outdoor/heat-source unit
Loose connectors found?
YES
NO
Check wiring inside outdoor/heat-source units
G/A terminal board/Inverter board
Faulty wiring?
YES
NO
Check diode stack
Check for torn wire or poor connections
Replace inverter board
Check power-supply wiring, main power
Fix loose connectors
Fix wiring
Replace diode stack
Replace surge breaker
Power ON
Check for short-circuited indoor/outdoor
transmission line
Check wiring between connectors CNS1-TB3.
If no problems are found, replace main board.
Check wiring between connectors
CNVCC2-CNVCC3
Damaged?
YES
NO
Surge breaker resistance check
4.5~5.5k
Ω
NO
YES
(3) Outdoor Unit Power-Supply Circuit Check
