Heater Problems with my 95 cadillac deville
 

Hello, I started having heating problems with my 95 Cad Deville winter 2018. I had just enough heat coming out of the vents to defrost the windows but still not warm on the body. I noticed when the weather was above 30s it was coming out hot. but then it got into the teens or lower , no heat. The only time I'd have heat is when it was warmer temp outside. Odd but anyways. I took it into a mechanic and they put in a new thermostat and a new radiator and my boyfriend checked the actuator doors and they were fine. The day I picked it up of course was a decent day, around the 40s, there was heat coming out. Then the next chilly day, again just enough warm air to defrost the windows. I've owned this car for a few years and noticed when I set temp to 72, air comes out of the vents on dash, but when it set temp higher for heat, air only comes out for defrost and to warm legs, no air coming out of dash vents. Thought it was a "CADDY THING"...lol
Any help is greatly appreciated.

Other things we have done...

Did heater core flush
water pump replaced
radiator hoses replaced


other notes...checked codes and fuses. no problems detected