Abstract: A method of operating an absorption heat pump or refrigerator consisting at least of a refrigerant circuit and a refrigerant-containing solution circuit, with a generator for evaporating refrigerant from the solution with the supply of relatively high-temperature heat, a condenser for condensing refrigerant and giving up heat at an intermediate temperature level, an evaporator for evaporating refrigerant with the absorption of heat from a relatively cold heat source, a heat exchanger for transferring heat from the liquid passing out of the condenser to the refrigerant vapor and liquid coming from the evaporator, an absorber for absorbing refrigerant vapor into the solution with the giving-up of heat at an intermediate temperature level, and means for circulating the solution or maintaining the pressure, wherein the delivery of refrigerant is regulated in such a manner that the temperature differential .DELTA.t.sub.