On Board Diagnosis of A/C System Refrigerant Charge Level

The air conditioning system of a car uses the reverse Carnot thermodynamic cycle of a refrigerant gas. The fluids normally used have at least a direct impact on global warming, so their losses have to be avoided. A very simple method to detect refrigerant charge level was developed, using few standard sensors. Results show that it is possible to have an estimation of system charge level with satisfactory accuracy, and seems able to avoid complete loss of refrigerant.