Air filter monitoring system and method for a work machine

A method of monitoring a fresh air filter through which fresh air enters a plenum and a recirculation air filter through which recirculated air enters the plenum in a work machine HVAC system, wherein the HVAC system includes a pressurization blower having a first motor for driving the pressurization blower, a recirculation blower having a second motor for driving the recirculation blower, a speed selector, and a non-transitory computer readable medium comprising a program instruction for permitting a controller to monitor the HVAC system, the method comprising:

• producing a first motor control signal to drive the pressurization blower at a first motor speed, the first motor control signal being a function of a speed select signal from the speed selector to maintain a constant speed from the pressurization blower to an outlet despite changes in the condition of the fresh air filter;
• producing a second motor control signal to drive the recirculation blower at a second motor speed, the second motor control signal being a function of the speed select signal to maintain a constant speed from the recirculation blower to the outlet despite changes in the condition of the recirculation air filter monitor;
• producing a first motor current sensor signal by a first motor current sensor, the first motor current sensor measuring a first current to maintain the first motor speed;
• producing a second motor current sensor signal by a second motor current sensor, the second motor current sensor measuring a second current to maintain the second motor speed;
• comparing the first motor current sensor signal to a first baseline motor current sensor signal and the second motor current sensor signal to a second baseline motor current sensor signal;
• identifying which filter requires replacement based on the first motor control signal and the second motor control signal;
• and
• triggering a filter replacement action when the first motor current signal falls below a first threshold value of the first baseline motor current sensor signal or the second motor current sensor signal falls below a second threshold value of the second baseline motor current sensor signal.

A non-transitory computer readable medium comprising a program instruction for permitting a controller to monitor the air filters on an HVAC system of a work machine, the program instructions when executed comprising causing a processor of the controller to:

• produce a first motor control signal to drive the pressurization blower at a first motor speed, the first motor control signal being a function of a first speed sensor signal to maintain a constant speed from the pressurization blower to an outlet despite changes in the condition of a fresh air filter;
• produce a second motor control signal to drive the recirculation blower at a second motor speed, the second motor control signal being a function of the speed select signal to maintain a constant speed from the recirculation blower to the outlet despite changes in the condition of the recirculation air filter monitor;
• producing a first motor current sensor signal by a first motor current sensor, the first motor current sensor measuring a first current to maintain the first motor speed;
• producing a second motor current sensor signal by a second motor current sensor, the second motor current sensor measuring a second current to maintain the second motor speed;
• compare the first motor current sensor signal to the second motor current sensor signal;
• and
• trigger a filter replacement alert when a difference between the first motor current sensor signal and the second motor current sensor signal exceed a threshold value;
• identify which filter requires replacement based on the first motor current sensor signal and the second motor current sensor signal;
• and
• perform a filter replacement action based on the filter replacement notification.