I have a 2005 Nissan Altima which I recently just started having problems with my heat. When my car is warming up it heats up but no real hot heat is coming out the vents, it is normally warm air. When I excellerate heat begins to come out but it is not as hot as normal. I checked my coolant and I filled this up it does not seem to be the problem. What would you suggest could be the problem?

Depending upon where you live, this link may give you an idea that will help minimize the effect of winter cooling:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post262690

Also, flush out the heater core if you suspect there may be corrosion or other blockage. A faulty thermostat can also cause overcooling. Ensure the control valve and blender door operate properly.