Hitachi YUTAKI Series - Page 216

Troubleshooting
Service Manual
214
Troubleshooting procedure
SMGB0066 rev.0 - 12/2009
 
U

• Watertemperatureisincreasedto65ºCbyheatgenerationinpumporotherheatsourceduringonlypumprunning
(during compressor stop: during thermo off or during pump automatic operation in winter).
• Ifwatertemperatureisdecreasedlessthan6ºCduetopumpstop,itbecomesnormalstatusautomatically.
• Sincethisisnotanabnormalityofunit,itisnotsavedinalarmhistory.
Whenthisalarmhappen,checkthewatersystemrst.Ifanycausecannotbedetected,checktheunitaccordingto
the following procedure.

note
Measure the resistance at least in 2 different points which is different more than 10 ºC. -
Are the connectors between
PCB1 and PCB2 correctly
connected?
PWB1
CN9-CN1
PWB2
CN5-CN2
CN6-CN3
CN2-CN4
No
Yes
Pull out connector
and measure thermistor
resistance.
Isresistancecorrect?
No
Replace thermistor
Yes
Are connectors CN3 and CN9
onPCB2correctlyconnected?
No
Yes
Wiringcheck,Repair.
(Breakingofwire,wrongwiring)
Wiringcheck,Repair.
(Breakingofwire,wrongwiring)
Failure of PCB1.
Replace PCB1.
Is the actual water temperature
and the water temperature shown
insegmentproper?
Yes
No
Check water system of heat load
side
PCBmonitoringposition:PCB2,CN3andCN9