I have an older second car...a Honda Accord...not sure of the year, I think 98 (it's my Aunt's).
I noticed towards the end of the summer the AC was fading and not getting as cold. I didn't worry about because it was nearly Fall. But now I am noticing the heat no longer blows hot air...not even warm. Is this most likely the Thermostat?

 

Look at the temp gage. If its not in the 'normal' zone for the car it probably is the thermostat. If the temp gage is normal maybe have a blocked heater core.

 

Ok, cool. Thanks.

 

beathorse

 

Could also be that the coolant level is low-this can cause a no heat situation-also an air pocket in the cooling system can cause this if not purged when the coolant is changed.

 

Coolant level check your rad cap.