Automotive secondary loop air conditioning system

An automotive air conditioning system includes a primary, refrigerant loop (10,12,14) and a low pressure secondary loop (22, 24, 26, 28) across which heat is exchanged by a chiller (16). A liquid coolant reservoir (24, 42) in the secondary loop has a provision to allow the majority of its volume to be incorporated incrementally into the system at start up after the reservoir (24, 42) has sat long enough to become heated, so as not to delay the attainment of a suitable passenger comfort level.