Bosch C1210ESC Technical Service Bulletin page 2

2 | C6 & C7 Error Code Troubleshooting
9. Check that the wire connections to the control board are fi rmly
attached to the board. Removal of the lower access cover on
the control board is required. Refer to Bulletin TWH-G3-24.
10. Remove wire connection from back of fan, plug in heater and
turn power on with water shut off. Check for voltage AC on the
plug between the 1st and 2nd pin. You should fi nd 120VAC (Fig.
3)
a. If the plug shows 120 VAC between the pins, the
primary fan needs to be replaced.
b. If the plug shows no voltage between the pins; shut
power off, disconnect plug from the outlet, and check
the 2.5A white fuse inside of the control unit (Fig. 4).
Refer to Bulletin TWH-G3-24. If the 2.5A white fuse has
continuity, then the control unit needs to be replaced.
c. If the 2.5A fuse is blown, replace with spare from the
back cover of the control unit, remove the connection
from the primary fan, and remove both wire connections
from the secondary fan (Fig. 5).
d. Reconnect primary fan only, turn power on, run
water for 30 seconds. LEAVE SECONDARY FAN
DISCONNECTED
Data subject to change without notice | Printed in the USA | BTC 740002330 A | 05.2014
Figure 2
Figure 3
e. If fan turns on, unit ignites, and/or E4, then shut the
power off and reconnect the secondary fan. If C6 or C7
and/or the fuse blows before connecting the secondary
fan then the primary fan needs to be replaced.
f. With both primary and secondary fans connected, turn
power on, and run water. If no issues, then just a bad
fuse. If the 2.5A fuse blows then the secondary fan
needs to be replaced.
After completing this procedure, please
the unit at 1-800-798-8161 for diagnosis and resolution. If
it is more convenient for you, please email the results of
this procedure to ldy.asa@us.bosch.com and we will reply
within one business day.
Technical Service Bulletin
Figure 4
Figure 5
call us while still at
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: 1-800-283-3787
Fax: 1-603-965-7581
www.bosch-climate.us
Bosch Thermotechnology Corp.