Any idea what could be wrong with it? It's a 2007 Volvo s40.
My heating blower still blows air but it is not warm? on 2007 Volvo S40
No hot air could be anything from a defective thermostat to a control module needing replacement or possibly just a software update for the climate control module! You should take the car to a Volvo specialist and have them diagnose it for you. This way you'll know what needs to be repaired instead of guessing and maybe even spending money on repairs not needed.