The alternator belt recently broke off on my Mazda Protege and by the time I was able to drive it to my local Mazda dealer to have the belt replaced the engine was completely dead. I drove the car about 12 miles after the alternator belt broke. I noticed as I was driving to the dealer that my heater was not working; the fan was working but it would only blow cold air. I know that the alternator belt also controls the water pump, so I tried to keep my engine rpm’s below 2000 while driving to avoid overheating the engine. On the way to the dealer the temperature gauge on the dashboard increased to about halfway between cold © and (H), which is where it usually sits after the engine warms up. The belt was replaced, but I have noticed that ever since then the temperature gauge always sits at “C” and the engine never warms up. The heater continues to not produce any warm air. In addition, I have felt the engine with my hand after driving for about 20 minutes, and although it feels warm, it is not nearly as hot as it should be. I suspect that the engine cooling system is continually working for some reason, instead of allowing the engine to warm to its optimal operating temperature and then maintaining the temperature at that level. Because this coincided with my alternator belt breaking, I suspect that the root of the problem is either electrical in nature or associated with the water pump somehow. However, I don’t know enough about cars to figure it all out. Please help.
Perhaps your thermostat is stuck open
Another thing to check . . . make sure your coolant level is correct