High Country Tek HFS-2Q - Manual (Page 9)

Hydraulic Fan System Controller : HFS - 2
Charge Air :
There can be a special case of cooling requirements when the engine is warming up
from a cold start. For this situation, the controller has a ‘Cold Engine Fan Limit’
option available to the user which if enabled, will temporarily stop the fans rotation
to prevent excessive cooling.
The ‘Charge Air’ temperature can easily exceed its desired setpoint value while the
Engine Coolant temperature is still too cold to let the standard mechanical
thermostat open
thermostat open.
Normal operation would allow the ‘Charge Air’ temperature to capture the fan
control, cooling any other above ambient liquids in the radiator.
This would typically cause a sudden introduction of cold water when the engine
does eventually warm up enough to cause the thermostat to open, resulting in the
chance of engine block damage with thermal shock.
‘Ch g Ai ’ t ll d f d l l d gi ti g ti g ll ti ‘Charge Air’ controlled fan speed can also slow down engine warm-up time generating unnecessary pollution,
inefficient running and excess fuel usage. On a cold start, reversing the fan during a ‘purge cycle’ will have a
similar effect as most radiators will then be cooled by the air sucked from around the cold engine.
The ‘Cold Engine Fan Limit’ feature avoids these problems by not allow the Charge Air OR Reversing inputs to
take control of the Fan speed while the Engine Coolant temperature is less than the ‘Engine Warm Temp’
setpoint.
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The Engine Coolant sensor MUST be connected to Thermistor 1 input and set to type
Thermistor.
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The ‘ Charge Air ’ sensor MUST be connected to Thermistor 2 input and may be set to type
Thermistor or Switch.
Fan control by the thermistor 1 and 3 inputs is not limited by the ‘Engine Warm Temp’ setpoint. While the unit
Important Notes:
1 ‘Ch Ai ’ t t hi th t d ‘O t ’ t i t’ ill id th ‘C ld E i
y p y g p p
is waiting for thermistor 1 to reach engine warm temperature, clearing the ‘Cold Engine Fan Limit’ will not exit
the waiting mode.
1. ‘Charge Air’ temperature reaching the user entered ‘Overtemp’ setpoint’ will override the ‘Cold Engine
Fan Limit’ and go to full fan forward rotation while the condition exists, to ensure that damage does not
occur and that the Overtemp condition is reduced.
2. The ‘Charge Air’ limiting feature only functions when power is initially applied to the controller.
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3. The ‘Warm engine temp’ setting MUST NOT exceed the ‘Coolant’ temperature setpoint.