Heater not working properly

[mikeyboltz272]

I have a 96 Tacoma LX and the heater barley works on the 1 and 2 fan speeds. Any higher and the air isn't warm at all. There's a new thermostat in it, the engine doesn't run hot, yet the water pump is squealing alot. I'm thinking it's either the water pump or the heater core. Anybody have any suggestions or experience with this kind of problem.

 

[OR17TRD]

Is it the water pump itself or the belt that's squealing a lot? If the water pump is failing they don't fail for long the go out. If it's the pump then the radiator fluid isn't flowing to the core as designed and the heater core requires said fluid to function properly.
If it's not the pump then most likely a plugged or failing heater core also air in the cooling system can cause some issues. Make sure the radiator fluid is topped off, low fluid can have an effect on the heat as well.