1970 OLDS 442 W-30 AUTOMATIC CONV W/ FACTORY AC...Just bought this car the other day...Mint cond.. When heater is selected and temp set to warm, cool air still blows out...AC is working excellent...Even when the AC is on and i set the temp to warm, still only ambient temp air comes out....When heater is selected, air does flow from the bottom duct....There is no smell of anti freeze...I have not had a chance to check things out yet, but i suspect heater control valve might be the problem..Any thoughts would be appreciated..

 

The temperature blend door is still cable operated even with A/C, so the first question is, is the cable working properly when you move the slider lever? Next question is, are both hoses to and from the heater hot when heat is selected? The heater control valve on these cars is normally closed and requires vacuum to open. Most catalogs incorrectly show the later normally open valve, which would then be closed with the controls in the HEAT position, so it's possible someone put the wrong valve on. It's possible the valve is stuck closed. It's possible there is no vacuum to the valve when the control is in the HEAT position. It's possible the heater core is plugged.

 

Cable is working properly..I'll have to check the temp on the hoses when I get off work today...but thank you..

 

Joe's pointed you in the right direction. Some trouble shooting necessary to determine the problem. Good luck!