No Heat -

Question:

My temperature gauge does not move past 170 and is will only blow warm air, not hot like it used to. My coolant level is full and its not overheating.... What could it be ?

Answer:

The most common cause for this situation is a Thermostat that is stuck in the open position. This allows the coolant to continuously flow through the engine. This keep the coolant from being able to get as hot as it should. Normal operating temperature is between 180-220 degrees. Have the thermostat replaced and all should move back to normal.

If by chance your thermostat is not stuck in the open position, then the most likely event is that your heater core is clogged and will need to be replaced.