Service Manual 32 – Contour 3 Series, Profiler & Advance – Approved Issue 5 Printed 2/13/2014 11:50:17 AM
52
Cooler Operation
(cont.)
Fan Operation
(cont.)
Speed Feedback
The fan motor is fitted with a speed sensor which signals the motor RPM back to the
N-E5 Cooler control.
The N-E5 must have a speed sensor fitted and operating or the unit will operate in a
FAN LIMP mode.
The sensor is fitted to the special stub shaft provided on the motor and uses a light
beam across the shaft flat section to register the revolutions of the motor's shaft.
The purpose of the sensor is to:
•
Detect if the fan motor (impellor) is rotating when the power is first applied to the
fan motor.
•
Detect if the fan motor is locked.
•
Detect if the fan motor is not rotating within the correct operating range.
If the N-E5 doesn't receive any signal from the speed sensor, or looses the signal, the
N-E5 will adopt a FAN LIMP mode operation.
Initially, when the motor is required to run and the speed signal is lost, the fan will
immediately increase its fan speed and may be driven to the maximum power for a
short time prior to commencing the Fan Limp Mode.
Then the FAN_LIMP mode will commence, however, there will be a 4 minute delay
before the error is displayed on the Networker (where available).
If the condition rectifies itself, and the speed sensor signal is restored, then the
Cooler will resume normal fan operation.