Controller for variable pitch fan system

A method of periodically changing a pitch of a variable pitch fan assembly mounted to a vehicle having an engine and an air conditioner system and configured for selectively controlling the direction of air flow to and from a cooling core comprising:

• selecting a predetermined temperature parameter for indicating a temperature condition of the engine;
• selecting a predetermined pressure parameter for indicating a pressure condition of the engine;
• determining whether a relay contact is closed and if so, energizing a high pressure solenoid to close a high pressure valve, otherwise;
• determining whether said temperature condition exists and if so, opening a temperature switch to de-energize a low pressure solenoid and open a low pressure valve, otherwise;
• determining whether said pressure condition exists and if so, opening a pressure switch to de-energize the low pressure solenoid and open the low pressure valve, otherwise;
• energizing both the low and high pressure solenoids to close both the low and high pressure valves.

An electronic control device for selectively controlling a pitch of a variable pitch fan of the type used to cool an engine and actuated by a valve assembly and capable of operating in at least one of a normal operating blade pitch position, a cooling blade pitch position, and a purge blade pitch position comprising:

• means for detecting a predetermined temperature of an engine;
• means for detecting a predetermined pressure in an air conditioning system;
• timed signal means for transmitting a signal for a predetermined duration following a predetermined time period;
• actuating means for actuating the valve assembly when at least one of temperature, pressure or time period has been reached;
• and
• actuating means for actuating said valve assembly.