why no hot air when i put it on defrost? on 1995 Dodge Stratus

When I have the heat on it blows out hoot air but when I turn it to defrost it drops like 30 degrees. I have changed the thermostat, flushed hte raditor and heater core, tore dash out and checked all the mixer doors and everythibng is working as it what?

Asked by for the 1995 Dodge Stratus
The reason the temp drops when you switch from "heat" to "Defrost" is because the Air Conditioning Compressor is engaged to help remove moisture from the vehicle interior, thus defrosting the windshield. This is normal operation. Make sure you have the engine Coolant at the correct level and that the engine is at correct operating temperature (195 degrees). if not, replace the thermostat