This paper describes a work in progress on the development of general, Open Architecture multi-resolution software for rapid prototyping and analysis of complex systems using a Co-simulation approach. Although the approach can be used for rapid analysis of a wide class of complex physical systems, the current focus of this work is on the modeling of the engine cooling system in the Ford Escape Hybrid SUV vehicle. The paper discusses two aspects of this work: development of the co-simulation environment, development of models of the cooling system components with focus on the A/C system using the R134a refrigerant. The major component models are based on dimensional reduction of the 3D Navier-Stokes equations. The resulting 1D equations are subsequently partitioned along the axial direction resulting in systems of 0D non-linear ordinary differential equations. The equations are then solved using a very efficient approach using Chebyshev polynomials. We also present preliminary results on component response to variations in selected system parameters.