As far as always having heat the 190's have a vacuum operated valve that opens for heat and closes when you are wanting cooler air stopping the flow of coolant thru the heater core. These are prone to go bad and won't hold vac allowing you not to be able to control heat. It is on the passenger side of the firewall you have to pop out the plastic screen that is at the base of the windshield and the just look for a vac line running to a vac pod. Apply vac and see if it holds.