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Old 06-05-2007, 01:19 PM
Arthur Dalton Arthur Dalton is offline
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Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
Quote:
Originally Posted by rorypff View Post
oops, I think you mean the low side aux fan (controlled by the A/C HP switch) as the high side aux fan is certainly controlled by the engine coolant temp switch.
No ooops..time to learn some more.

The HIGH SIDE fan is controlled by the pressure of the HIGH SIDE, but it is a LOW SPEED fan
And the coolant temp of the engine controls the HIGH SPEED FAN..

You have your a/c pressure SIDES and your fan SPEEDS mixed up...
A refrigeration systems has two sides.. HIGH/LOW and that refers to the pressure of the system

The aux fan has two SPEEDS ..HIGH and LOW and that refers to how FAST/SLOW the fan motors RPM is..

To make it simple:

If the high side pressure goes up due to high thermal load conditions, the high side a/c pressure sw closes and activates the LOW SPEED AUX FAN/CIRCUIT.

,,and if the engine coolant gets to 105C due to high thermal load conditions, the coolant temp thermistor sensor activates the HIGH SPEED FAN/CIRCUIT.
That's all..

Last edited by Arthur Dalton; 06-05-2007 at 01:28 PM.
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