Benchmark ZWB 7-29 CC1 Installation And Servicing page 73

C1
flashing.
Fan speed too low
Check
1. Fan lead connector properly con-
nected?
2. Is fan lead defective?
B Is impedance reading between the
two connectors for one of the
cores infinity?
3. Are the differential pressure switch
contacts closed?
B Press button
B Select service function 3.8 .
Is left digit of display showing 1?
4. Fan defective?
5. The PCB control board is damaged.
7 181 465 346 GB (03.02)
yes:
no:
yes:
no:
yes:
no:
.
yes:
no:
Failure identification procedure
Action
↓2.
B Power OFF the appliance.
B Plug in connector.
B Turn ON the appliance.
C1? ↓2.
B Power OFF the appliance.
B Replace fan lead.
B Turn ON the appliance.
C1? ↓3.
↓3.
↓4.
↓4.
B Power OFF the appliance.
B Plug the connection wire.
B Replace fan.
B Plug the connection wire.
B Turn ON the appliance.
C1? ↓5.
↓5.
B Make a note of the altered service settings (see
table 1, "First Service Level; Values that can be
modified" at page 8 and table 5, "Secondary
Service Level; Values that can be modified" at
page 11).
B Power OFF the appliance.
B Disconnect the boiler electrical connection.
B Change PCB control board.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
B Restore service settings previously noted down.
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