97 GA has no heat

I have a 97 ga that has no heat. I have changed the thermostat but still no help. I dont think the heater core is bad, I dont smell coolant & it is not leaking & car is not overheating. The AC works great but when I turn it to heat it still blows cool but not as strong. Please help.

Sir I believe i know what your problem is. I as well have a problem getting much heat in my car. I took it to several places who all could not figure it out. I got a full system flush as well as my thermostat changed out but no luck. I found out only recently that the problem may in fact be that there is a leak in the in take manifold. The cost to fix this little number starts at 400$ if your lucky. I guess i'll suffer threw it myself. After researching online i found a site that talked about GM cars having problems with the intake manifold because GM makes that gasket out of plastic instead of silicone. Hope that helps.