Your HVAC company should be able to determine the cause of the problem. There could be more than one issue that creates the same syptom but it takes depth of experience to ferret out the cause.
If YOU want change, YOU have to first change.
If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!