[Merc Cruzer]

Originally Posted by artron9

Rayfry: the vac hose goes to the vac thermostat valve located in the heater plenum. It is actuated by the heat temp slider located on the Magic -Aire controller at the bottom of the dashboard to the right of the steering wheel. It controls the temp from OFF-HIGH.
My heater problem is solved. I replaced my heater hoses in the engine compartment. I made sure all were routed correctly(thanks to you guys). I replaced the heater control valve (Rayfry) this is also located in the engine compartment. On initial startup, cold air continued to fill the cabin. I removed the upper exit tube from the heater core and primed it with coolant. That seemed to be the problem solver. If there is an air pocket somewhere in the circulatory system, hot water will not enter and/or leave the heater core.
By the way heat control valves can pricey. I found a new one on Ebay for $17.95. I'm sure it is imported but so are the $100 ones. I bought it because it looked exactly like the one I replaced even though it was listed for a more modern vehicle. Thanks again to all of you for your advice and continued support .Ron

Good to hear, stay warm.