Bosch C 1210 ESC Reference manual

Technical Service Bulletin:
C6 & C7 Error Code Troubleshooting
Models: C1210ESC, C1210ES, C1050ES, C950ES, 940ES, 940ESO, 830ES, 2400ES,
2700ES, 715ES, C800ES, C920ES/ESC, Integra 500, Evolution 500
Introduction
This procedure must be performed by a qualified technician.
DANGER!
120 VAC present in wire connections. Use caution
when testing.
Follow the procedures below and report results to Bosch Technical
Support. This will assist in determining the cause and solution to the
problem.
C6 and C7 error codes
These errors are fan-related error codes with the following
explanations:
C6 error indicates the primary fan rotation is too low during
operation.
C7 error indicates there is no primary fan rotation sensed
during an attempted start-up.
Primary Fan Assembly
The primary fan is a 120 volt AC fan that receives power from
the main control board.
The primary fan has its own built-in circuit board which relays
information and signals back to the control board.
Tools needed:
Phillips head screwdriver
Digital Multi-meter
Procedure
1. Press the reset button on the control panel of the heater to
attempt to clear the error code. If the error code does not reset
or continues to reoccur, proceed with the following trouble-
shooting steps.
2. Confirm that the exhaust vent is not blocked and does
not exceed the specified maximum length as shown in the
installation manual.
3. Ensure that the 3 foot minimum separation between air intake
and exhaust vents is met (applies to a twin pipe vent system).
4. Verify the heater is plugged into a properly grounded 120V AC
power supply.
5. Supply the heater with a steady supply voltage. It is
recommended to supply electricity from a dedicated electrical
circuit with no other major appliances on the same circuit.
6. Shut off power to the heater and unplug from electrical outlet.
Remove cover per installation manual.
7. Remove the black plastic intake (Fig.1, pos.1) that is secured
with three Phillips head screws to the fan (Fig.1, pos.2).
Figure 1
8. Check the wire connection to the fan. The wire connection is
located on the back, left hand side of the fan housing. (Fig. 2).

Data subject to change without notice | Printed in the USA | BTC 740002330 A | 05.2014 Bosch Thermotechnology Corp.
Technical Service Bulletin
2 | C6 & C7 Error Code Troubleshooting
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: [phone]
Fax: [phone]
www.bosch-climate.us
Figure 2
9. Check that the wire connections to the control board are firmly
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 find 120VAC (Fig.
3)
Figure 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
Figure 4
Figure 5
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 call us while still at
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[email protected] and we will reply
within one business day.