C954, C956 Treadmill
20077-107 Page 27
Procedure 5.4 - Troubleshooting the Fan Sensor (Units
manufactured prior to 9/29/2000)
Note:
The fan sensor function was discontinued on 9/29/2000. This section pertains only to units
manufactured prior to 9/29/2000. The fan sensor is an infrared photo-eye sensor that emits a
pulse when the infrared beam emitted by its transmitter is reflected back to its receiver. A
reflective “target” covers half of the fan hub. Therefore as the fan rotates, the infrared beam is
reflected during half of the fans rotation and is not reflected during the other half of the fans
rotation. This causes the speed sensor to emit a square wave pulse train that indicates the fans
rotating speed. Circuitry on the lower logic PCA processes the pulse train emitted by the fan
sensor and determines if the fan speed is within the normal operating range. If the fan speed is
found to be below nominal limits, a fan speed error will occur (error 13).
1. If the drive motor cooling fan is operating and an error 13 is occurring, go to step 15.
2. If the drive motor cooling fan is not operating continue with step 3.
3. Set the treadmills circuit breaker in the “off” position and remove the AC line cord from the
AC outlet.
4. Remove the F3 (Fan) fuse from the lower logic PCA. Using an ohmmeter, check the
resistance of the F3 fuse. See Diagram 5.2. The fuse should measure approximately 1 Ω or
less. If the fuse is open or high resistance, replace the fuse.
5. Insert the treadmills line in the AC outlet and set the circuit breaker in the “on” position. If the
drive motor cooling fan operates normally, test treadmill operation per Section 3. If the drive
motor cooling fan still does not operate, retest the fan fuse per steps 3 & 4. If the fuse is
open again, go to step 12. If the fuse is good continue with step 6.
6. Set the treadmills circuit breaker in the “off” position. Remove the fan wires from terminals
M2 (blue) and M3 (brown) of the lower logic PCA. See Diagram 5.2. Set the treadmills circuit
breaker in the “on” position. Carefully measure the voltage between terminals M2 & M3 of
the lower logic PCA. The meter should read AC line voltage (120 Vac or 240 Vac). If the
reading is 0 or significantly low, replace the lower logic PCA.
7. Set the treadmills circuit breaker in the “off” position. Using an ohmmeter, measure the
resistance between the blue and brown wires that were removed from the lower logic PCA.
The ohmmeter should read approximately 345Ω.
8. If the resistance if significantly high or open, remove the blue and brown wires from the fan.
9. Measure the resistance between the two terminals of the fan. The reading should be
approximately 345Ω. If the reading is open or significantly high, replace the drive motor
cooling fan per Procedure 6.7.
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