Hvac system for mobile machine

A method of controlling an HVAC system in a mobile machine having a frame and a cabin supported by the frame, the method comprising:

• pumping coolant through a first heat exchanger in thermal contact with the frame of the mobile machine to transfer heat between the coolant and the frame;
• pumping coolant from the first heat exchanger through a second heat exchanger;
• and
• generating a flow of air through the second heat exchanger and into the cabin.

A mobile machine, comprising:

• a frame;
• an engine mounted to the frame;
• a cabin supported by the frame;
• a first temperature sensor configured to generate a first signal indicative of an actual cabin temperature;
• a first heat exchanger configured to exchange heat between coolant and the frame;
• a first pump configured to circulate coolant through the first heat exchanger;
• a second heat exchanger configured to receive coolant from the first heat exchanger;
• a fan configured to generate a flow of air through the second heat exchanger and into the cabin;
• an engine bypass;
• a first control valve fluidly connected downstream of the first heat exchanger and movable to direct coolant through the engine or around the engine via the engine bypass;
• a second control valve fluidly connected downstream of the engine and the engine bypass and upstream of the second heat exchanger;
• a third control valve downstream of the second heat exchanger;
• a first heat exchanger bypass disposed between the first control valve and the third control valve;
• and
• a controller in communication with the first temperature sensor, the first, second, and third control valves and configured to:
• receive an indication of a desired cabin temperature;
• move the first control valve to direct coolant through the engine bypass to the second control valve when the desired cabin temperature is lower than the actual cabin temperature;
• move the third control valve to direct coolant to the first control valve through the first heat exchanger bypass when the desired cabin temperature is higher than the actual cabin temperature;
• and
• move the third control valve to direct coolant through the first heat exchanger when the desired cabin temperature is lower than the actual cabin temperature.