Heating and AIR conditioning is often just a breaker switch away from many issues, ducting inspection is required in all cases where lack of flow is noticed, so DIY, get up in the attic and perform a simple visual test, often just a roll of duct tape will suffice. Repair when possible before any estimates to replace when applicable. Quick annual filter replacement or cleaning will allow your system a healthy long life and of coarse save you your hard earned money for other things you may want or need, last choice for many of us is to have to call the guy!

Some info on your HVAC system, helping get a better understanding of the FUNDAMENTALS