I have a 94 Toyota Tercel with 90K miles and the heater does not blow hot air. The engine temperature guage goes up to a normal temp, but there is very little heat coming into the car. The fan works fine, too. We replaced the thermostat, but think it was faulty since the engine temp guage went high with that thermostat, so we put the old one in. We also did a cooling system flush. What things do we need to check? It's getting cold here in CT!