REFRIGERANT CHARGE DIAGNOSTIC PROCEDURE FOR VEHICLE HEAT PUMP SYSTEMS

A diagnostic for heat pumps may include causing heated coolant in a coolant loop to circulate through a heat exchanger that is thermally coupled to a refrigerant loop. The temperature and pressure of the refrigerant may be measured while the heated coolant is circulated through the heat exchanger, and the measured pressure and temperature may be compared to pressures and temperatures for systems that are properly charged with refrigerant to determine if the heat pump system is properly charged.