Bosch C1210ESC Technical Service Bulletin

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 qualifi ed 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. Confi rm that the exhaust vent is not blocked and does
not exceed the specifi ed 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).
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).
Figure 1