89 Toyota Corolla Runs Hot

I have an 89 Corolla with 192,000 on it. I have had the car for over 2 years. I had to replace the radiator shortly after I purchased the car. During the winter the car is fine. During the warmer months I have to run the defroster continously to keep the car from running hot. It never actually gets hot enough to overheat but it sure gets warm in the car. I never lose any water . Any ideas? thanks

have you replaced the thermostat?

Wire the thermo fans to stay on when the ignition is on. I did that after I got the extractors put on. I think you just have to unplug a switch.